2014-2016 Seminar Abstracts


Recollimation shocks in Astrophysical Jets

Tim Cawthorne

Highly supersonic flows respond to abrupt changes in the
pressure of their surroundings through either one, or a series of shock
structures known as recollimation shocks. In astrophysical jets, these
shock waves leave a mark on the underlying (largely disordered) magnetic
field, which can be detected through polarization.




This seminar will present a brief introduction to astrophysical jets.
Earlier work, using a semi-dynamical model to derive the characteristic
polarization of recollimation shocks, will be reviewed, and more recent
work, in which I attempt to model features observed in AGN jets in terms
of such structures, will then be presented.

The Changing Picture for the Formation of the Galactic Bulge of the Milky Way

Melissa Ness

Galactic bulges are an important signature of Galaxy formation as different
kinds of bulges are formed in different ways. Understanding the bulge of the
Milky Way and its formation places important constraints on which processes have
been important in the evolution of the Milky Way and disk galaxies in general.
Our overall picture of the Galactic bulge of the Milky Way has changed in the
last few years. The formation scenario has shifted from one emphasising the
bulge as a distinct population in the Milky Way, formed via mergers or
dissipational collapse before the disk, to one where dynamical formation from
the disk is considered to play an important role. This shift has been driven by
larger data sets, examining more dimensions of information and using models to
compare to data and understand the observational signatures. I will present the
latest results for the bulge, demonstrate why models are key to make
interpretations about observational data and highlight the steps that need to be
taken to test what fraction of stars in the bulge are a unique population that
is distinct from the disk.

Using the Milky Way as a template for understanding star formation in
extreme environments across cosmological timescales

Steven Longmore

The Milky Way contains large reservoirs of gas with properties directly
comparable to most of the known range of star formation environments in the
Universe. As such, it is an excellent template for studying star formation
across cosmological timescales. I will show how we have been using studies of
gas in the Milky Way to learn about star formation in high-redshift clouds and
galaxies and super star cluster formation. These results strongly challenge the
universality of currently accepted star formation theories. I will discuss the
implications of this for our understanding of star and planet formation as a
whole, and how this may relate to supermassive black hole growth and feedback in
the centre of galaxies.

Hard X-ray and radio observations of non-thermal electrons in solar flares

Heather Ratcliffe

Solar flares release large amounts of energy, part of which goes into the
acceleration of electrons. These non-thermal electrons can travel downwards from
the acceleration site, to the dense solar chromosphere and produce hard X-rays
due to collisional bremsstrahlung. Electrons which travel upwards along open
field lines, can produce intense radio bursts. Known as Type III solar radio
bursts, these show high brightness temperature and rapid frequency drift. Here,
I will discuss some recent theoretical work on electron transport, including the
influence of Langmuir, or plasma, waves. I will show how these can affect the
HXR emission in the first case, and lead to radio emission in solar coronal
loops. Langmuir waves are also essential in Type III burst production. I will
show some recent simulations of such bursts, and the physical origins of their
parameters. Finally, I will briefly discuss how these two very different
observations can complement each other and provide information on electron
acceleration in flares.

The Herschel Space Telescope – What It Told Us About the Formation of Stars

Derek Ward-Thompson

The Herschel Space Telescope flew from 2009 until 2013 and carried out a number of key programmes. I will present much of the latest data from one of these programmes, known as the Herschel Gould Belt Survey. This programme surveyed most of the nearby star-forming regions at 5 wavelengths from 60 to 500 microns, giving us key insights into the formation of low-mass, solar-type stars, and generating a huge data-set, which we have only begun to study in detail. However, already interesting results have begun to emerge relating to the link between the Initial Mass Function (IMF) of stars and the core mass function (CMF) of gravitationally bound objects, known as prestellar cores. Furthermore, the processes governing the formation and evolution of prestellar cores are now becoming clearer, and the role played by filamentary structures now appears crucial. The probability density function (PDF) of the cloud structure also yields valuable insight into the formation mechanism of prestellar cores. I will conclude by presenting the first evidence for a new paradigm of solar-mass star formation.

Mysteries and Challenges Posed by the Highest Energy Cosmic Rays

ALan Watson

Cosmic rays were discovered in 1912 as a result of efforts by some of the most distinguished scientists of that era to explain the discharge of ionisation detectors. The results of the study of cosmic rays have impacted on many disciplines, including astrophysics, particle physics, carbon dating and radio astronomy. I will describe some of the early work that led, inter alia, through the use of the Wilson cloud chamber, to the discovery of the positron, the muon and the first strange particles and thus to the birth of particle physics. In 1938 it was found that showers of particles reaching the ground simultaneously are produced by primary cosmic rays of >1e15 eV, about 1e5 times more energetic than any particle that had then been contemplated. I will discuss how study of these showers led to the discovery of cosmic rays of energies as great as 3e20 eV, more than the kinetic energy of a tennis ball from Andy Murray’s first serve. This presents an on-going challenge to understanding where and how Nature can organise the production of particles with such macroscopic energies. I will overview data from the Pierre Auger Observatory, the largest cosmic-ray detector ever built, on the energy spectrum, mass composition and arrival direction distribution of cosmic rays with energies above 1e18 eV. These measurements are used to constrain the location of the sources of these remarkable particles. No background knowledge of cosmic rays or particle physics will be assumed.

Central Massive Objects in Galaxies

Elena Dalla Bonta

The evolution of galaxies is closely entwined with their nuclear
properties and much attention has recently focused on the study of
central massive objects (CMOs), which can be constituted of either a
supermassive black hole (SBH) or nuclear star cluster (NC). SBHs and
NCs are not mutually exclusive and thus can coexist in some galaxies,
and determination of their demography and scaling relations between
their masses and larger galaxy properties can provide important clues
on how CMOs form and grow with their hosts. We present a method to
constrain the masses of both the SBH and NC, by modelling the
kinematics of the ionised gas disc and the surface brightness
distribution. We also show the results obtained by applying this
method to a nearby lenticular galaxy.

Astronomy in Afriace during Mediavel Times

Thebe Medupe

Conventional wisdom has us believe that mathematical astronomy came to Africa only in the 1820s when the Cape Observatory was built. Prior to this Africans practised cultural ethno-astronomy. However, the ancient manuscripts from the city of Timbuktu in Mali, West Africa reveal that African scholars where studying and practising mathematical astronomy as early as the 1500s and even earlier. In this presentation I will discuss the type of Astronomy that was taught at Timbuktu schools as revealed in the two manuscripts written by Timbuktu scholars. I will demonstrate for example, how they used Polaris to measure their city’s latitude, and used lunar eclipses to measure longitude. I will take you through the discoveries that our research team made about African astronomy and convince you that the history of Astronomy in Africa can be divided into Cultural, Medieval and Modern, just like in other continents.

Galaxy Interactions in the Nearby Universe

Nicola Brassington

It is widely believed that very few galaxies exist today that have not been formed or shaped in some way by an interaction
with another galaxy. These interactions play a major role in the evolution of galaxies by triggering star formation and nuclear
activity. However the parameters that influence this enhanced activity are poorly understood. The Spitzer Interacting
Galaxies Survey (SIGS) is addressing this question by using IR data obtained with the Spitzer Space Telescope to study a
large sample of 104 galaxies in different stages of interaction. In this talk I will provide an summary of the sample and
present the results from the photometric analysis. I will also discuss our recent work on HI and CO data which
allow us to determine the properties of the ISM of these systems. I will specifically focus on the interacting systems
that contain one gas-rich and one gas-poor galaxy; the damp-mergers. Such systems provide us with the opportunity to study
how cold gas from the gas-rich galaxy is affected by its companion and thereby, in conjunction with the Spitzer data,
provide constraints on the relationship between the ISM and star-formation in interacting systems containing a gas poor
system.

Looking at the Fossil Record to Discover How Galaxies Form

Ignacio Ferreras

The photometric and spectroscopic data of galaxies encode a treasure
trove of information about how galaxies form and evolve. In this talk
I will present an overview of recent work focusing on the so called
two-phase formation scenario through the analysis of the stellar
populations in early-type galaxies from low (z less than 0.1) to intermediate
redshifts (z of approximately
1.5). The analysis of spectroscopic observations over
the past 9 Gyr of cosmic history reveals an intriguing decoupling
between the formation of the core, in an early and efficient burst,
and the outer envelope, whose formation takes place at later times.
The observational findings gathered over the past few years provide
very strong constraints on models of galaxy formation and evolution,
from the rate of mass assembly via mergers, to the physics of star
formation in extreme environments.

Where is the matter?

Kathryn Johnston

A major accomplishment for large scale stellar surveys of the Milky Way has been
the discovery of a multitude of debris structures from dead and dying satellites
encircling our Galaxy. These structures unequivocally demonstrate the Milky
Way’s cannibalistic history, in agreement with our understanding of how
structure formation proceeds in the Universe more generally. They also delve
deep into our dark matter halo and provide invaluable probes of its mass
distribution. This idea is particularly interesting at the moment with the
prospect of significant improvements to the quantity, quality and dimensionality
of stellar data sets that map debris. Recently, there has been renewed vigor in
developing and testing techniques that can use this data to place rigorous
constraints on the large-scale structure of our dark matter halo. While the
Milky Way is “just one galaxy” it is the only one where we can hope to measure
the 3-dimensional structure of a dark matter halo – not just the overall mass,
but the shape, orientation and density as a function of radius. In this talk I
will describe the properties that make debris structures such effective
potential probes and outline the observational and analytical efforts being made
to exploit these properties and pin down exactly where the matter is around our
Galaxy.

Modelling the Spectral Energy Distributions of Herschel galaxies:
gravitational lenses, cold dust and young starbursts

Michael Rowan-Robinson

I will give some background on our developing understanding of infrared
galaxies, from the IRAS mission in the 1980s to today’s Herschel Space
Telescope. The three main types of infrared galaxies are quiescent
galaxies in which interstellar dust is heated by staright, starburst
galaxies in which new stars are being formed at a prodigious rate, and
active galaxies, in which gas falling into a black hole illuminates a
surrounding dust torus. Herschel has shown the presence of much colder
dust in some galaxies than found previously, some very young starbursts,
and a surprisingly high incidence of distant infrared galaxies magnified
by the effect of an intervening gravitational lens.

The Origin of the Elements and the Critical Role of Binary Stars

Rob Izzard

In a few millennia of recorded history, mankind has made great strides in its understanding of the Universe. We now know that the Big Bang created almost all visible matter as just two elements, hydrogen and helium, some which was later turned into carbon, oxygen, iron and the 90+ other chemical elements by nucleosynthesis in stars. Many of these stars are gravitationally bound as close binary systems which can evolve quite differently to single stars leading to exotic phenomena such as thermonuclear novae and gamma-ray bursts. Binaries are crucial to galactic chemical evolution, particularly through type Ia supernovae which make most of the iron in the Universe.

By comparing statistical models of binary star populations with observations, we can better understand many processes in stellar astrophysics. For example, chemically peculiar stars, such as carbon-enhanced metal-poor and barium stars, are difficult to reproduce both in number and binary orbital properties with conventional stellar models. Much of my recent work has involved statistically testing new theories of mass transfer and orbital interactions to explain these and other unusual binary stars. Statistical methods are also predictive and I will report on new calculations of a binary-star source of the most contemptuous element in the Universe: lithium. Canonical Galactic chemical evolution models of lithium make too little by a factor of (at least!) three. Mass ejection from binary stars offers an alternative, hitherto ignored, source of lithium which helps to solve this problem but creates a few more along the way.

Finding binaries among Kepler pulsating stars from phase modulation
of their pulsations

Simon Murphy

Asteroseismology is our only method to observe the stellar interior. Ultimately
we aim to build up internal rotation and density profiles for stars of a range
of masses and radii, but modelling our asteroseismic observations requires those
masses and radii to be well known. Our fundamental method for obtaining those
quantities is through the study of binary stars. Thus pulsating stars in
binaries are of paramount importance to our understanding of stellar structure
and evolution. I will present a recently-developed method for finding binaries
among pulsating stars that were observed with the Kepler mission. This method
focuses on the change in pulsation phase caused by the motion of a star in its
binary orbit, and the extra light travel time thereby introduced. This
pulsational phase modulation allows us to calculate the orbital period,
eccentricity, and the projected light travel time across the orbit. All of this
is done with existing Kepler data, and removes the need for ground-based
spectroscopic radial velocity measurements. Moreover, the method has been
applied to thousands of Kepler targets, including but by no means restricted to
eclipsing binaries. A sneak peak at some results for delta Scuti pulsators in
binaries will be given.

Seismic view of the inconstant Sun

Shashikumar Chitre

The internal layers of the Sun are not accessible to direct observations.
Nonetheless, it is possible to infer the physical conditions prevailing in the
Sun with the help of equations governing its equilibrium coupled with
observational inputs provided by neutrino fluxes and accurately measured
frequencies of solar oscillations. These complementary probes enable us to
determine the internal structure and dynamics of the Sun.

With the accumulation of helioseismic data over the solar cycle 23 and beyond,
it has now become possible to study the temporal variations occurring in the
solar interior. An outstanding problem in Solar Physics is to provide a
plausible mechanism which can account for an almost synchronous variation with
the solar activity cycle, of oscillation frequencies, rotation rate, magnetic
field and total solar irradiance. Hopefully, the emerging field of
magnetoseismology will help us to surmise the magnetic field configuration and
meridional circulation pattern in the solar convection zone with a view to
understand the basic mechanism driving the sunspot cycle.

The Formation and Dynamical Evolution of Free-Floating Planets in Star Clusters

Thijs Kouwenhoven

The recent discovery of a large population of exoplanets in the Galactic field has provided a wealth of information that helps us understand how planetary systems form and evolve. Exoplanet surveys targeting star clusters, on the other hand, have been less successful: only a hand full of exoplanets have been discovered in these regions. This may be attributed to the frequent encounters experienced by star cluster members, and possibly by a difference in the formation process. The presence of multiple planets in a system (such as our own Solar system) can substantially increase the possibility of planet ejections, which may explain the absence of close-in planets, such as hot Jupiters, that would normally be unaffected by stellar encounters. This talk focuses on the dynamical fate of multi-planet systems in dense stellar systems and on the evolution of the free-floating planet population in star clusters resulting from destabilized planetary systems. Since most of the planet-hosting stars in the Galactic field (and probably even our own solar system) are thought to have formed in clustered stellar environments, this places limits on the properties of the star clusters they may have formed in.

The Chemistry of Galaxy Discs: Reconstruction and Dissection

Owain Snaith

The chemistry of stars encodes a huge amount of information about the history of a galaxy. The chemical abundances of stars of a given age encode information about the conditions in the ISM from which those stars formed.
I will present recent work which used a simple chemical evolution model to reconstruct the star formation history of the Milky Way using a sample of stars in the solar vicinity with very good abundances and ages. The recovered star formation history implies a very massive thick disc component in the Milky Way, containing half the stars in the Galaxy.
Subsequently, I will present the results of our exploration of the chemical evolution of galaxies from the MUGS and MAGICC cosmological SPH simulations. These galaxies have the same initial conditions but implement different feedback. We used a variety of methods to pull apart the different components of the galaxies, and examined the how the chemistry evolves in the simulated disc, bulge, satellites etc. We find that the MUGS galaxies is replete with substructure, while much of this is lost in the MAGICC galaxy

Angels and Demons: Active Galactic Nuclei Sub-grid Models

James Wurster

In galactic and cosmological simulations, feedback prescriptions (both stellar and AGN) must be implemented using subgrid models. The physics that is assumed can vary greatly between models, thus different assumptions can naturally lead to different results. Likewise, different numerical assumptions or interpretations can also lead to different results. I will discuss several different AGN feedback models, which were all numerically tested using the same numerical code and the same initial conditions (for non-feedback related parameters). I will highlighting the similarities and differences amongst the models, as well as discuss possible observational tools to differentiate between the models.

Why The Sun Is Not As Boring As Many Astronomers Believe It Is!

Graham Barnes

R.B. Leighton is attributed with saying that “If the Sun did not have a magnetic field, it would be as uninteresting a star as most astronomers believe it to be.” I will give an overview of magnetic fields in the Sun, starting from the generation of fields via a dynamo in the interior through the formation of active regions to the release of free magnetic energy in the corona in the form of solar flares and coronal mass ejections. I will then briefly describe our efforts to forecast flares.

Turning a Telescope on Finance

Thomas Babbedge

I will explore how the skills and experiences gained from astrophysics research can also be applied to systematic investment strategies, as well as some of the similarities and differences between astrophysics and finance. I will also discuss the issues of data-mining and over-fitting that arise from big data and cheap computing power and the publication bias that can creep into both science and finance results. Hopefully I will also be able to point to some approaches to combating these problems!

Supermassive Black Holes, Nuclear Star Clusters, and Nuclear Stellar Discs in Galactic Nuclei

Elisa Portaluri

I will present the main results of my PhD thesis which was focused on the investigation of the physics of the galactic central regions, exploring some aspects of the central massive objects (CMOs) found to live in the galactic nuclei, such as their formation scenarios, stellar properties, scaling relations, and coexistence of several CMOs. In fact, they can be in the form of supermassive black holes, nuclear star clusters, and nuclear stellar discs.
A variety of methods aimed to understand the connection between these objects are shown, ranging from N-body simulations, photometric and spectroscopic analyses of archival HST imaging and ground-based integral-field spectroscopy up to dynamical models, used to investigate stellar populations, and estimate the masses of CMOs.

The Star Formation History of Classical Dwarf Spheroidal Galaxies

Thomas de Boer

In this talk, I will present the detailed Star Formation History of three nearby classical dwarf spheroidal galaxies, from wide-field photometry of resolved stars, going down to the oldest Main Sequence Turn-Off. The detailed Star Formation History quantifies the star formation rate at different ages and metallicities and at different positions in the galaxy. We show that all classical dwarf spheroidals display a population gradient as a function of radius, in metallicity as well as age.
The obtained SFH is further used to determine accurate age estimates for individual RGB stars with spectroscopic abundances, obtaining the accurate age-metallicity relation of each galaxy, as well as the temporal evolution of alpha-element abundances. This allows us to determine, for the first time, an accurate age of the “knee” in the alpha-element distribution.
Finally, we compare the timescale of chemical evolution in classical dwarf spheroidal galaxies, and determine whether the chemical abundance patterns seen in galaxies with recent episodes of star formation are a direct continuation of those with only old populations.

Measuring Star Formation in Galaxies

Mederic Boquien

How galaxies form and evolve across the Universe is one of the greatest
outstanding questions in modern astrophysics. Yet this is a topic shrouded in
mystery. To get an insight into galaxy evolution, we have to understand the
fundamental process that drives the transformation of baryonic matter in
galaxies: star formation. Indeed, young, blue, massive, and very luminous
stars drastically affect the spectral energy distribution of galaxies, form
heavy elements that enrich the interstellar medium and, due to feedback,
inject metals into the intergalactic medium. Understanding how the gas
reservoir of galaxies is transformed into stars is therefore pivotal to
understanding galaxy formation and evolution. Unfortunately, measuring star
formation across the Universe remains difficult. The overarching aim of this
talk is to present and discuss some of the main challenges we still need to
overcome to measure star formation accurately and precisely, so we can finally
enter a new era in the study of galaxy evolution. In particular, I will
highlight some recent results from major surveys of nearby galaxies and how
numerical simulations can provide us with a unique insight into star formation
tracers.

The Habitability of Planets

Charles Cockell

Other planets in the Solar System much as Mars are thought to have hosted habitable conditions in their past. However, these environments may be very different to those we are familiar with on the Earth. Different types of salts and novel extremes may define quite different environments. I will present theoretical and laboratory-based studies on the limits to life in extremes and what defines the boundaries to the biosphere elsewhere.

Where Did the First Metal-Enriched Stars Come From?

Britton Smith

It is well known that stars observed in the local universe form with
something very close to a universal initial mass function (IMF) where
the vast majority are of low mass. However, this cannot be the case
for the very first stars to ever form as a similar IMF would yield
many surviving to the present day, contradicting the fact that none
have ever been observed. Theory and simulation have also suggested
that the first stars likely had a more top-heavy IMF owing to their
unique chemical makeup. This implies that a transition in star
formation modes must have taken place at some point in the history of
the universe. Like the formation of the first stars, this critical
epoch exists outside of the range of direct observation and, as such,
has been primarily the domain of theory. I will give a review of
research into the formation of the first (Population III) stars and
the transition from Population III to modern-day star formation. I
will then present new results from a set of simulations designed to
directly simulate the conditions of this period. Finally,
I will conclude with a brief presentation of the yt simulation
analysis toolkit, whose aim is to become a lingua franca for
astrophysical simulations by allowing researchers to focus on physical
objects instead of files on disk, regardless of the simulation code
they use.

The Gaia-ESO Tour of the Milky Way

Clare Worley

The creation of a 3D chart of a billion stars in the Milky Way is the primary goal of the Gaia Satellite. In order to take full advantage of the Gaia distances as they become available, the Gaia-ESO Survey is already building a comprehensive complementary chemical map of Gaia targets within key stellar populations. I will present of tour of the Milky Way from the range of exciting first science already coming out of Gaia-ESO as well as presenting results from other ongoing studies in this unfolding field of Galactic Archaeology.

The Habitability of Planets

Charles Cockell

Other planets in the Solar System much as Mars are thought to have hosted habitable conditions in their past. However, these environments may be very different to those we are familiar with on the Earth. Different types of salts and novel extremes may define quite different environments. I will present theoretical and laboratory-based studies on the limits to life in extremes and what defines the boundaries to the biosphere elsewhere.

Using Supernovae to Probe Star Formation

Stacey Habergham

Core-Collapse Supernovae (CCSNe) occur at the end of a massive stars
lifetime. Despite years of intense research on the exact nature of the
progenitor systems of these explosions, much uncertainty still surrounds
them. Investigating the environments in which CCSNe explode allows us to
constrain the progenitors of various subtypes of SNe, and use the
statistical distributions of the different subtypes to probe the host
galaxies star formation properties. The results of this analysis show an
excess of stripped-envelope SNe (with potentially more massive
progenitors) in the central regions of interacting host galaxies along
with a range of other interesting distributions. I will discuss these
distributions along with the possible explanations and interpretations
of the results.

Saturn’s Magnetosphere: Highlights from 10 Years of the Cassini Mission

Catriona Jackman

The first spacecraft to fly by Saturn were Pioneer 11, Voyager 1 and Voyager 2. Yet these gave us just a mere glimpse of the fascinating environment near Saturn. The Cassini spacecraft, one of the most successful missions of all time, went into orbit about Saturn in 2004, and has now delivered 10 years of amazing scientific discoveries. I will provide an overview of some of the key discoveries that relate to Saturn’s magnetosphere, from the water vapour from Enceladus, to the enigmatic rotation rate, to the presence of dynamic magnetic reconnection events which play a role in mass loss. I will show how what we have learned at Saturn can be compared and contrasted with other planets in our solar system, and even applied beyond, to the case of stellar magnetospheres. Finally I will explain what lies in store for the final 3 years of the Cassini mission, including its dramatic finale.

Nuclear Stellar Systems – a window on galaxy formation and evolution

David Cole

Nuclear star clusters are among the densest stellar systems known and are common in both early- and late-type galaxies. They exhibit scaling relations with their host galaxy which may be related to those of supermassive black holes. These may therefore help us to unravel the complex physical processes occurring at the centres of galaxies. The properties of nuclear stellar systems suggest that their formation requires both dissipational and dissipationless processes. I will talk about the work I have been doing simulating the formation nuclear stellar objects due to in-situ star formation and its relation to dissipationless processes such as formation due to the merger of star clusters.

Nuclear star clusters are among the densest stellar systems known and are common in both early- and late-type galaxies. They exhibit scaling relations with their host galaxy which may be related to those of supermassive black holes. These may therefore help us to unravel the complex physical processes occurring at the centres of galaxies. The properties of nuclear stellar systems suggest that their formation requires both dissipational and dissipationless processes. I will talk about the work I have been doing simulating the formation nuclear stellar objects due to in-situ star formation and its relation to dissipationless processes such as formation due to the merger of star clusters.

Supernova-driven gas accretion in the Milky Way

Antonino Marasco

Disc galaxies like the Milky Way need a continuous supply of gas to sustain their star formation. However, there is little observational evidence for accretion of cold gas occurring at the rate required. I present a model of the galactic fountain where cold gas, ejected from the disc into the halo by supernova feedback, triggers the cooling and the subsequent accretion of a significant portion of the inner circumgalactic medium (corona). I apply this model to the Milky Way and I show that a) it reproduces the kinematics and the distribution of both neutral and ionised gas in the halo of our Galaxy; b) it predicts an accretion of coronal gas onto the disc at a rate of a few Mo/yr, enough to sustain the star formation in the disc.

Nuclear Stellar Systems – a window on galaxy formation and evolution

David Cole

Nuclear star clusters are among the densest stellar systems known and are common in both early- and late-type galaxies. They exhibit scaling relations with their host galaxy which may be related to those of supermassive black holes. These may therefore help us to unravel the complex physical processes occurring at the centres of galaxies. The properties of nuclear stellar systems suggest that their formation requires both dissipational and dissipationless processes. I will talk about the work I have been doing simulating the formation nuclear stellar objects due to in-situ star formation and its relation to dissipationless processes such as formation due to the merger of star clusters.

The Evolution of Spiral Galaxies in the Group Environment

Richard Tuffs

Although the process by which galaxies obtain the
gas needed for star-formation is amongst
the most fundamental controlling the formation of the
baryonic structure in the Universe, there is very
little in the way of empirical evidence with which to
probe this process. In particular, the
postulated environmental dependencies of the gas fuelling of
galaxies, although widely modelled, remain largely unconstrained.
Here I present a quantitative study of the effect
of the group environment on star-formation rates (SFRs) of
spiral galaxies in the local Universe, using the
multiwavelength photometric and spectroscopic data
from the Galaxy And Mass Assembly (GAMA) survey.
The results are used to identify and quantify the influence of
the dynamical mass of the group haloes
on gas flows between the IGM and the interstellar medium of
central and satellite spiral galaxies, as
mediated by feedback on the IGM driven by star-formation and
AGN activity, and by gas-dynamical
interactions between the spiral galaxies and the IGM.

Modified Gravity Simulations and Galaxy Evolution in Clusters

Graeme Candlish

In the first part of this talk I will discuss recent work to modify the RAMSES N-body/hydrodynamics code to use the modified gravitational interaction given by MOND. After describing the motivation for this project, I will briefly discuss the formulations of MOND implemented by the modified code and the computational challenges involved. Finally I will give some brief examples of tests and future applications of the code. In the second part, I will discuss the use of phase space analyses in understanding galaxy evolution in clusters, combining LCDM cosmological simulations with HI observations from the Blind Ultra-Deep HI Environmental Survey (BUDHIES). Our study focussed on ram-pressure stripping, allowing us to demonstrate its effect on the quenching of star formation in galaxies in an observed cluster. Furthermore, I will demonstrate that such analyses enable a statistical understanding of the environmentally-driven evolution of galaxies in the cluster environment.

JSPS London Presentation

The JSPS is Japan’s leading funding agency and is largely funded through annual subsidies from the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). Established in 1932, JSPS promotes the advancement of academic research in all disciplines from social sciences and humanities to natural sciences and engineering. JSPS main functions are:

  • (i) Funding research initiatives;
  • (ii) Fostering next generation of scientists;
  • (iii) Advancing international collaborations;
  • (iv) Promoting university reform.

They provide a mixed diet of funding opportunities from short visits to Japan to mid-career Fellowships. More details can be found at this link, http://www.jsps.org/funding/index.html.

To book your place at the event please register here. Please also see attached programme for further details of the event.

The JSPS is Japan’s leading funding agency and is largely funded through annual subsidies from the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). Established in 1932, JSPS promotes the advancement of academic research in all disciplines from social sciences and humanities to natural sciences and engineering. JSPS main functions are:

(i) Funding research initiatives;

(ii) Fostering next generation of scientists;

(iii) Advancing international collaborations;

(iv) Promoting university reform.

They provide a mixed diet of funding opportunities from short visits to Japan to mid-career Fellowships. More details can be found at this link, http://www.jsps.org/funding/index.html.

To book your place at the event please register here. Please also see attached programme for further details of the event.

From Gas to Stars in Galaxies

Adrianne Slyz

Despite differences in their cosmological life stories, galaxies follow a seemingly simple script for star formation:
gas transforms itself to stars at a rate which depends on the average gas surface density of a galaxy.
For years, galaxy formation simulations have exploited this simple global relationship to make stars,
but nature is indicating that more than gas surface density is at play. Turbulence in the star forming gas appears to be key.
I will describe the evidence for this and current theoretical ideas of how turbulence shapes star formation. I will then
discuss attempts to capture the effect of turbulence on star formation in high resolution cosmological simulations of individual galaxies,
which incorporate results from resolved molecular cloud simulations. Consequences for stellar feedback, galaxy mophology, interstellar medium structure
and dynamics will be presented.

The Origin and Fate of Rings in Protoplanetary Disks: Diversity of Planet Formation Mechanisms

Shu-ichiro Inutsuka

Protoplanetary disks are supposed to be the sites of planet formation, and thus, understanding of the evolution of the disk is crucial in understanding of the planet formation. Recent ALMA observation revealed a remarkable multiple ring structure in a protoplanetary disk around HL Tau. Prior to this observation, Takahashi & Inutsuka (2014) proposed a possible formation of multiple ring structures by secular gravitational instability in the case of weak turbulent diffusion. This talk describes the condition for this to occur in detail and discuss the further evolution of the rings. A possible scenario for the formation of rocky objects at outer regions of the disks is outlined and contrasted with the other formation scenarios.

Modified Gravity Simulations and Galaxy Evolution in Clusters

Arianna Di Cintio

Using a suite of simulated galaxies we investigate the effects of
baryonic feedback on the density profiles of dark matter haloes.
The main result is a clear dependence of the inner slope of the
dark matter density profile on the ratio between stellar-to-halo mass.
The most cored galaxies are expected to have
Vrot=50 km/s while massive spirals, with Vrot in excess of 150 km/s,
are approaching again the NFW profile.
This prediction for cusps vs cores can be applied to the Local Group
galaxies and it allows to reconcile at the same time abundance matching
prediction, the measured shallow dark matter profile in some of
the Local Group members, the “too big to fail” problem and the star
formation efficiency of such galaxies.

Critical Effects of Collisional Fragmentation on Planet Formation

Hiroshi Kobayashi

The collisional coagulation of planetesimals, which are formed in protoplanetary disks, produces planetary embryos. Once planetary embryos become about 10 Earth masses, they cannot have hydrostatic atmospheres and the rapid accretion of gas from protoplanetary disks occurs, resulting in the formation of gas giants, such as Jupiter, Saturn, and massive exoplanets. In the classical theory of planet formation, the final embryo mass is determined only by the solid surface density. However, embryos can stir surrounding planetesimals, leading to destructive collisions and fragmentation. Radial drift of small fragments reduces the solid surface density. On the other hand, embryo growth is accelerated by fragment accretion. Since collisional fragmentation efficiency depends on the initial size of planetesimals, the final embryo mass and its growth time are determined by the initial planetesimal size and disk surface density. Small initial planetesimals are prone to fragmentation, so mass loss occurs through gas-induced drift of fragments. As a result, small planetesimals tend to produce small embryos (and vice versa). The eccentricities and inclinations of fragments produced by collisions between small planetesimals are damped by interaction with the gas. The resulting reduction in relative velocities increases the gravitational cross section of embryos for fragments, so small planetesimals allow rapid embryo growth (and vice versa). Final embryo masses thus depend on initial planetesimal sizes as well as disk masses; we give a constraint on plantesimal sizes and disk masses for the formation of gas giants. In addition, I will talk about this planetesimal size is determined by the strength of turbulence in protoplanetary disks.

The Shocking Corona

Peter Gallagher

Coronal mass ejections (CMEs) are large-scale eruptions of plasma and magnetic field from the Sun. As they expand into interplanetary space, they can produce radio bursts at decametric and metric radio frequencies (~10-500 MHz), which are thought to be associated with shocks. In this talk, I will describe how CME kinematics derived from SOHO and STEREO coronagraphs can be combined with dynamic spectra and radio images from instruments such as e-Callisto, LOFAR and the Nancay Radioheliograph to give us a better understanding of shock formation.

Critical Effects of Collisional Fragmentation on Planet Formation

Hiroshi Kobayashi

The collisional coagulation of planetesimals, which are formed in protoplanetary disks, produces planetary embryos. Once planetary embryos become about 10 Earth masses, they cannot have hydrostatic atmospheres and the rapid accretion of gas from protoplanetary disks occurs, resulting in the formation of gas giants, such as Jupiter, Saturn, and massive exoplanets. In the classical theory of planet formation, the final embryo mass is determined only by the solid surface density. However, embryos can stir surrounding planetesimals, leading to destructive collisions and fragmentation. Radial drift of small fragments reduces the solid surface density. On the other hand, embryo growth is accelerated by fragment accretion. Since collisional fragmentation efficiency depends on the initial size of planetesimals, the final embryo mass and its growth time are determined by the initial planetesimal size and disk surface density. Small initial planetesimals are prone to fragmentation, so mass loss occurs through gas-induced drift of fragments. As a result, small planetesimals tend to produce small embryos (and vice versa). The eccentricities and inclinations of fragments produced by collisions between small planetesimals are damped by interaction with the gas. The resulting reduction in relative velocities increases the gravitational cross section of embryos for fragments, so small planetesimals allow rapid embryo growth (and vice versa). Final embryo masses thus depend on initial planetesimal sizes as well as disk masses; we give a constraint on plantesimal sizes and disk masses for the formation of gas giants. In addition, I will talk about this planetesimal size is determined by the strength of turbulence in protoplanetary disks.

Theoretical Aspects of Particle Acceleration in Solar Magnetic Activity Processes

Thomas Neukirch

Investigating solar magnetic activity processes such as flares and coronal mass ejections is one of the major research areas in solar physics. A particular challenge in this area is trying to find a theoretical explanation for the acceleration of a large number of charged particles to high energies during solar flares. A crucial part of this challenge is the vast difference between the microscopic (kinetic) and the macroscopic (magnetohydrodynamic, MHD) scales involved in the acceleration process. Whereas many of the large-scale phenomena associated with flares can be reasonably well explained, using e.g. MHD models, this is so far not the case for the small-scale (kinetic) aspects, in particular the particle acceleration processes and the inherent coupling between the physical processes across the different scales. In this talk, I intend to give an overview of the problems we face and discuss a few of the more recent theoretical developments in the area of solar flare particle acceleration.

Theoretical Aspects of Particle Acceleration in Solar Magnetic Activity Processes

Thomas Neukirch

Investigating solar magnetic activity processes such as flares and coronal mass ejections is one of the major research areas in solar physics. A particular challenge in this area is trying to find a theoretical explanation for the acceleration of a large number of charged particles to high energies during solar flares. A crucial part of this challenge is the vast difference between the microscopic (kinetic) and the macroscopic (magnetohydrodynamic, MHD) scales involved in the acceleration process. Whereas many of the large-scale phenomena associated with flares can be reasonably well explained, using e.g. MHD models, this is so far not the case for the small-scale (kinetic) aspects, in particular the particle acceleration processes and the inherent coupling between the physical processes across the different scales. In this talk, I intend to give an overview of the problems we face and discuss a few of the more recent theoretical developments in the area of solar flare particle acceleration.

The role of angular momentum in the dynamical evolution of star clusters

Anna Lisa Varri

In the last few years our traditional interpretative paradigm of the internal dynamics of globular star clusters (GCs) has been revolutionized by a series of discoveries about their chemical, structural, and kinematic properties. The existence of multiple stellar populations is now regarded as a ubiquitous phenomenon, while for decades GCs have been viewed as the epitome of a “simple stellar population”. In addition, little attention has been traditionally paid to the role played by angular momentum in the dynamical evolution of these systems, yet an increasing number of young and old star clusters (and nuclear star clusters!) are now being observed to have evidence of rotation. The synergy between recent HST proper motion studies and the astrometric mission Gaia will soon allow us to unlock the full phase space of these stellar systems, with unprecedented detail. Such a tremendous observational progress, coupled with recent improvements on the side of numerical simulations, calls for a renewed effort on dynamical modelling.

Driven by these motivations, I will present the results of an ongoing numerical and analytical research program devoted to the investigation of the dynamical evolution of rotating stellar systems, from the early to the final stages of evolution. In particular, I will discuss: 1) the dynamics of dissipationless collapse in the presence of non-vanishing initial angular momentum, with focus on the resulting structural and kinematic properties that may characterize dynamically young rotating star clusters; 2) the stability properties of equilibria with differential rotation, with attention to the analogies between fluid and stellar rotating spheroidal systems; 3) the role of angular momentum in the evolution towards and after core collapse, with emphasis on the interplay between angular momentum transport and relaxation processes.

Multi-dimensional Convection in Stars

Chris Geroux

I will present two applications of multi-dimensional hydrodynamic simulations to explore questions about stellar physics.

The first application explores the interaction of convection and radial stellar pulsation. Early non-linear calculations of stellar pulsation used a 1D Lagrangian framework and had considerable success producing full amplitude RR Lyrae models. However there are some short comings of these models, the most notable of which is the poor handling of convection. To improve on these models, while keeping the benefit of a Lagrangian coordinate, a 1D/2D/3D radiation hydrodynamics code with a pseudo Lagrangian radial coordinate was developed to follow the pulsation while including convection in a natural way by directly following the convective flow using conservation laws. I will present my numerical simulations of pulsating RR Lyrae stars and their comparison with observations.

The second application explores how accreted material is redistributed by convection in young stars. These young stars form in clusters which show large spreads in luminosity of the member stars (e.g. Bayo et al. 20011). Baraffe et al. (2009,2011) showed with a 1D stellar evolution model including different accretion histories could lead to different structures and thus luminosities. These models made the assumption that the accreted material was uniformly distributed throughout the star however there is little understanding of what the actual distribution of mass should be or to what degree the energy of the accreted material is incorporated into the accreting star. I will present some recent work towards understanding how newly accreted material is distributed throughout such a young star by convection.

Multi-dimensional Convection in Stars

Chris Geroux

I will present two applications of multi-dimensional hydrodynamic simulations to explore questions about stellar physics.

The first application explores the interaction of convection and radial stellar pulsation. Early non-linear calculations of stellar pulsation used a 1D Lagrangian framework and had considerable success producing full amplitude RR Lyrae models. However there are some short comings of these models, the most notable of which is the poor handling of convection. To improve on these models, while keeping the benefit of a Lagrangian coordinate, a 1D/2D/3D radiation hydrodynamics code with a pseudo Lagrangian radial coordinate was developed to follow the pulsation while including convection in a natural way by directly following the convective flow using conservation laws. I will present my numerical simulations of pulsating RR Lyrae stars and their comparison with observations.

The second application explores how accreted material is redistributed by convection in young stars. These young stars form in clusters which show large spreads in luminosity of the member stars (e.g. Bayo et al. 20011). Baraffe et al. (2009,2011) showed with a 1D stellar evolution model including different accretion histories could lead to different structures and thus luminosities. These models made the assumption that the accreted material was uniformly distributed throughout the star however there is little understanding of what the actual distribution of mass should be or to what degree the energy of the accreted material is incorporated into the accreting star. I will present some recent work towards understanding how newly accreted material is distributed throughout such a young star by convection.

Following the tracks of planets in transitional discs with SPHERE and ALMA

Maria De Juan Ovelar

Transitional discs are young circumstellar discs that depart considerably form the continuous gas and dust distribution commonly seen in protoplanetary discs. They feature localised depletion of gas/dust in the form of holes and/or gaps, and often structures such as azimuthal asymmetries, spi- rals, etc… Theoretical studies have shown that the presence of a planetary-mass companion triggers physical mechanisms that could potentially explain some of these features; an exciting possibility since, by looking at these discs, we could be directly looking into the process of planet formation. But planets are not the only possible explanation and we need observational tools that help disentangling this scenario from others. The development of instruments such as SPHERE at the ESO Very Large Telescope and ALMA have brought us to the point where we can obtain exquisite high resolution images of these discs that allow for a detailed study of the distribution of not only gas and dust, but also dust of different sizes. By combining images from ALMA and SPHERE we can trace how small and big dust grains are distributed in the disc which, as we will see, can provide important clues about the mechanisms at play and even the type of planet that could be ”hiding” in the disc.

The Shocking Corona

Peter Gallagher

Coronal mass ejections (CMEs) are large-scale eruptions of plasma and magnetic field from the Sun. As they expand into interplanetary space, they can produce radio bursts at decametric and metric radio frequencies (~10-500 MHz), which are thought to be associated with shocks. In this talk, I will describe how CME kinematics derived from SOHO and STEREO coronagraphs can be combined with dynamic spectra and radio images from instruments such as e-Callisto, LOFAR and the Nancay Radioheliograph to give us a better understanding of shock formation.

Observations of Cosmic Rays in the Heliosphere

Simon Thomas

Galactic cosmic rays (GCRs) are extremely high energy charged particles that are accelerated at extra-solar sources such as supernovae. Upon entering the heliosphere, they are modulated by variations in the heliospheric magnetic field and are detected on Earth by neutron monitors. These variations could be short-term changes due to large eruptions of plasma from the Sun known as coronal mass ejections (CMEs) or to anisotropy in the trajectories of GCRs arriving at Earth. In the longer-term, these changes are due to solar variability, be it due to the 11-year solar cycle or longer-term trends which can be deduced from GCR secondaries in terrestrial reservoirs that give reconstructions of long-term solar variability. In this seminar I aim to discuss some recent advances and observations in the field of GCR modulation. In particular, I shall concentrate on modulation over solar-cycle time-scales, when we find that the 22-year cycle in GCR flux is, in part, due to changes in the heliospheric magnetic field between consecutive cycles. I will also discuss shorter modulations by solar transients; firstly describing how GCR data can be used to probe the locations of large CMEs and then presenting a survey showing changes in GCR behaviour across the heliospheric current sheet (HCS), with or without associated compression regions. The survey of HCS changes and the associated GCR changes are shown to have a surprising relation with terrestrial lightning rates and this result will be discussed at the end of the seminar.

Following the tracks of planets in transitional discs with SPHERE and ALMA

Maria De Juan Ovelar

Transitional discs are young circumstellar discs that depart considerably form the continuous gas and dust distribution commonly seen in protoplanetary discs. They feature localised depletion of gas/dust in the form of holes and/or gaps, and often structures such as azimuthal asymmetries, spi- rals, etc… Theoretical studies have shown that the presence of a planetary-mass companion triggers physical mechanisms that could potentially explain some of these features; an exciting possibility since, by looking at these discs, we could be directly looking into the process of planet formation. But planets are not the only possible explanation and we need observational tools that help disentangling this scenario from others. The development of instruments such as SPHERE at the ESO Very Large Telescope and ALMA have brought us to the point where we can obtain exquisite high resolution images of these discs that allow for a detailed study of the distribution of not only gas and dust, but also dust of different sizes. By combining images from ALMA and SPHERE we can trace how small and big dust grains are distributed in the disc which, as we will see, can provide important clues about the mechanisms at play and even the type of planet that could be ”hiding” in the disc.

On the acceleration regions of solar energetic particle events: two case studies

Ludwig Klein

Jets of energetic particles emitted by the Sun can on occasion be observed near Earth, mainly by space-borne detectors. Two candidate accelerators are solar flares, most likely through magnetic reconnection, and the shock waves driven by fast coronal mass ejections (CMEs). While there is a widespread trend to believe that shock waves are the most plausible accelerator, there is no unambiguous observational evidence confirming this viewpoint. In this talk I intend to introduce the subject of solar energetic particles (SEPs) and their relationship with radio emission in the corona and the interplanetary medium, and then to present two case studies of SEP events with very different characteristics:

(1) A small SEP event observed near solar minimum (26 April 2008). The quiet coronal and interplanetary conditions allowed us to distinguish different locations of electron and SEP acceleration, with clear evidence for the acceleration of the SEPs at the CME shock during its travel through the high corona, in the absence of any indication of particle acceleration during the impulsive flare phase.

(2) A large SEP event extending to relativistic (GeV) particle energies on 20 January 2005. The relativistic proton profile derived from ground-based particle measurements (neutron monitors) displayed a time structure that could be compared with gamma-ray, hard X-ray and radio emission at the Sun. Radio time profiles were used as injection functions in a model calculating the proton transport in the interplanetary magnetic field, showing an overall correspondence between the two relativistic proton peaks seen at Earth and two different episodes of particle acceleration in the corona. Both episodes were most likely related to magnetic reconnection in the impulsive flare phase and later on in the post-CME current sheet, not to the CME shock.

My conclusion is that particle acceleration proceeds in different regions in the course of a flare/CME event, including shock waves and magnetic reconnection in different phases of the CME/flare-development. These case studies are consistent with a scenario of energy-dependent acceleration, where CME shocks play a strong role at energies up to several tens of MeV and over long durations, while other mechanisms, such as magnetic reconnection, accelerate relativistic solar energetic particles.

Observations of Cosmic Rays in the Heliosphere

Simon Thomas

Galactic cosmic rays (GCRs) are extremely high energy charged particles that are accelerated at extra-solar sources such as supernovae. Upon entering the heliosphere, they are modulated by variations in the heliospheric magnetic field and are detected on Earth by neutron monitors. These variations could be short-term changes due to large eruptions of plasma from the Sun known as coronal mass ejections (CMEs) or to anisotropy in the trajectories of GCRs arriving at Earth. In the longer-term, these changes are due to solar variability, be it due to the 11-year solar cycle or longer-term trends which can be deduced from GCR secondaries in terrestrial reservoirs that give reconstructions of long-term solar variability. In this seminar I aim to discuss some recent advances and observations in the field of GCR modulation. In particular, I shall concentrate on modulation over solar-cycle time-scales, when we find that the 22-year cycle in GCR flux is, in part, due to changes in the heliospheric magnetic field between consecutive cycles. I will also discuss shorter modulations by solar transients; firstly describing how GCR data can be used to probe the locations of large CMEs and then presenting a survey showing changes in GCR behaviour across the heliospheric current sheet (HCS), with or without associated compression regions. The survey of HCS changes and the associated GCR changes are shown to have a surprising relation with terrestrial lightning rates and this result will be discussed at the end of the seminar.

Andrew Thomas

Surface interactions under realistic conditions, bridging the pressure gap

Surface science has provided a fundamental understanding of processes in areas as diverse as catalysis, biomaterial interfaces, sensors and corrosion. However, many of the techniques employed to understand these fundamental processes are carried out under high and ultrahigh vacuum, which has led to questions about how realistic the model systems really are.

This presentation will cover two relatively new techniques, which are now being employed in the Photon Science Institute in Manchester that operate at near-ambient and ambient conditions; Near Ambient Pressure Photoelectron Spectroscopy and vibrational Sum-Frequency Spectroscopy. The talk will cover the background and operation of the techniques and present recent data obtained using them.

Name

Title

abstract

Jill Evans

Research Data Management

Major research funders (Research Councils, charities and foundations) have now introduced policies on research data management. The general expectation is that data from publicly-funded research projects should be made openly available with as few restrictions as possible. For example, The Engineering and Physical Sciences Research Council (EPSRC) requires that selected data underlying published research should be made open access at the time the paper is published.

The research data management session will allow you to:

  • Find out about your funder and UCLan requirements for research data sharing
  • Understand the basics of writing a data management plan
  • Learn how to make your data open access
  • Ask any questions you might have directly to UCLan’s Research Data Manager

Jill Evans

Research Data Management

Major research funders (Research Councils, charities and foundations) have now introduced policies on research data management. The general expectation is that data from publicly-funded research projects should be made openly available with as few restrictions as possible. For example, The Engineering and Physical Sciences Research Council (EPSRC) requires that selected data underlying published research should be made open access at the time the paper is published.

The research data management session will allow you to:
· Find out about your funder and UCLan requirements for research data sharing
· Understand the basics of writing a data management plan
· Learn how to make your data open access
· Ask any questions you might have directly to UCLan’s Research Data Manager

Tyler Bourke

The Square Kilometre Array: Science Drivers and Status Update

The Square Kilometre Array (SKA) will be the world’s largest radio telescope when completed in the next decade. The past few years have seen great progress toward this goal, with construction beginning in 2018 and early science anticipated for 2020. In this presentation I will provide a status update on SKA activities, with a focus on the science it will enable and the avenues available for community involvement.

Name

Title

abstract

Matthew Forster

Diamond Light Source

The interaction of molecules with surfaces is of central importance to a wide range of topics including heterogeneous catalysis, fuel cells and corrosion, to name but a few. However, gaining an understanding of interfacial structures at the nanoscale is a considerable challenge requiring the use of commentary surface science techniques and, increasingly, insights from density functional theory (DFT) calculations.

In this talk I will discuss the interaction of ice, alkanes and amino-acids with various surfaces with insights provided from surface-sensitive experimental techniques including scanning probe, diffraction and calorimetry. For ice layers on a Cu(110) surface it has been demonstrated that unusual hydrogen bonded arrangements of water molecules are adopted including pentagonal [1], bjerrum defect [2] and incomplete H-bonded networks [3]. Amino-acid adsorption on the Cu(110) substrate leads to a complexity in chiral expression on the surface with enantiopure ensembles, racemic compounds and random solid solutions identified [4,5]. Finally, I will show that alkanes form self-assembled structures on the surface of hexagonal-boron nitride (h-BN) powders, with an odd-even dependence of the alkyl chain length on the symmetry of the structure adopted [6]. I will also discuss the mixing behaviour of alkanes on the h-BN surface and show that the phase behaviour is intimately linked to the symmetry of the pure components, with examples of ideal mixing, phase separation and partial mixing presented.

[1] J. Carrasco, A. Michaelides, M. Forster, S. Haq, R. Raval, A. Hodgson, Nature Materials 2009, 8, 427.

[2] M. Forster, R. Raval, A. Hodgson, J. Carrasco, A. Michaelides, Phys. Rev. Lett, 2011, 106, 046103

[3] M. Forster, R. Raval, J. Carrasco, A. Michaelides, A. Hodgson, Chemical Science, 2012, 3, 93.

[4] M. Forster, M.S. Dyer, M. Persson, R. Raval, J. Am. Chem. Soc. 2009, 131, 10173.

[5] M. Forster, M.S. Dyer, M. Persson, R. Raval, Angew. Chem. Int. Ed. 2010, 49, 2344.

[6] T. Arnold, M. Forster, A. A. Fragkoulis, J. Parker, J. Phys. Chem. C. 2014, 118, 2418.

Observations of Cosmic Rays in the Heliosphere

Simon Thomas

Galactic cosmic rays (GCRs) are extremely high energy charged particles that are accelerated at extra-solar sources such as supernovae. Upon entering the heliosphere, they are modulated by variations in the heliospheric magnetic field and are detected on Earth by neutron monitors. These variations could be short-term changes due to large eruptions of plasma from the Sun known as coronal mass ejections (CMEs) or to anisotropy in the trajectories of GCRs arriving at Earth. In the longer-term, these changes are due to solar variability, be it due to the 11-year solar cycle or longer-term trends which can be deduced from GCR secondaries in terrestrial reservoirs that give reconstructions of long-term solar variability. In this seminar I aim to discuss some recent advances and observations in the field of GCR modulation. In particular, I shall concentrate on modulation over solar-cycle time-scales, when we find that the 22-year cycle in GCR flux is, in part, due to changes in the heliospheric magnetic field between consecutive cycles. I will also discuss shorter modulations by solar transients; firstly describing how GCR data can be used to probe the locations of large CMEs and then presenting a survey showing changes in GCR behaviour across the heliospheric current sheet (HCS), with or without associated compression regions. The survey of HCS changes and the associated GCR changes are shown to have a surprising relation with terrestrial lightning rates and this result will be discussed at the end of the seminar.

Rich Townsend

MESA & GYRE: Stellar Astrophysics for the People

MESA (Modules for Experiments in Stellar Astrophysics) is a numerical code for modeling the structure and evolution of all types of stellar objects, from brown dwarfs through to the most massive stars in the Universe. It is available to everyone under an open source license, and since its release in 2011 has drawn an impressive following in the stellar astrophysics community.

GYRE (acronym pending) is a complementary open source code for calculating the oscillation frequencies of models produced by MESA and other stellar evolution codes. By comparing these eigenfrequencies against the oscillation spectrum of a real star (observed, e.g., by the Kepler satellite) one can place constraints on the structure of the star — the technique of ‘asteroseismology’. In the past year, GYRE has been integrated into MESA so that this process can be largely automated.

In this presentation I’ll give an overview of the physics, numerics and capabilities of MESA and GYRE. I’ll discuss the communities of practice that have sprung up around these codes, and describe how these communities are being further nurtured. I’ll then present some of the exciting projects enabled by the codes, such as observational signatures of core helium flashes; stellar probes of dark-matter physics; the metallicity dependence of the mass threshold for core collapse; and the generation of new sets of isochrones for use in other branches of astrophysics.

Name

Title

abstract

Marcella Carollo

MAD Science: The growth and death of galaxies

I will show results on how stellar mass builds up with time inside galaxies, and present the perspective that emerges, which unifies three major open questions in galaxy evolution, namely: (1) How do massive galaxies grow their dense bulges? (2) How do they quench their star formation activity? (3) What causes the observed growth with time of the average size of the quenched galaxy population? I will conclude with a look ahead on the MUSE Atlas of Disks (MAD), a just-started large program with the new MUSE IFU spectrograph on the ESO VLT. MAD anatomizes how gas and stars interact within galaxies on the tens-to-hundreds pc scales over which star formation and stellar feedback take place, providing fundamental constraints on the physical state that characterises the active phase of galactic life on the star-forming Main Sequence.

Name

Title

abstract

Jim Wild

Does Mars have a magnetic personality?

As recently as 20 years ago, Mars was thought to be an unmagnetised body where interactions with the magnetised solar wind would be dominated by the Martian ionosphere and induced magnetosphere. However, in situ measurements made by the NASA Mars Global Surveyor (MGS) mission revealed crustal magnetic sources, mainly confined to the southern highlands. Subsequent results from the MGS, ESA’s Mars Express, and NASA’s MAVEN missions have revealed that interactions between Mars and the magnetised solar wind are very different from those at the other terrestrial planets due to the presence of these crustal fields. The seminar will explore this contrast and discuss recent results from the red planet.

Name

Title

abstract

Wyn Evans

The Rough and the Smooth

The Milky Way stellar halo is built up from the serial killing of satellite galaxies. It is an important component to study, as it tells us about the past and the present — namely, the accretion history of the Galaxy together with the present state of its gravity field and hence dark matter distribution. The stellar halo is smooth in the inner parts, where memory of initial conditions has faded, but it is rough and splodgy in the outer parts where accretion continues to the present day. I will review recent progress in understanding which suggests that the smooth component moves in a nearly spherical gravitational field, whereas the rough component is dominated by the sinister Large Magellanic Cloud and its entourage of recently discovered satellite galaxies.

Name

Title

abstract

David Ward

Experimental surface science with helium beams; microscopy and spectroscopy for imaging and dynamics measurement

Helium atom beams have been exploited in surface science investigations because they can be formed into controllable beams, have immense surface sensitivity and a small enough wavelength for high resolution studies. In the talk I will cover the use of Helium beams in my research, both in measuring dynamics with the Surface spin-echo spectrometer, and then introduce the latest instrument in the helium scattering family: A neutral beam helium atom microscopy, which I have developed.

The helium spinecho instrument measured its first spectra in 2005, and since then has been used to investigate a wide range of processes and systems, from quantum motion of hydrogen [1] to more complex molecules such as Ionic Liquids [2]. The strength of the technique allows a variety of dynamical concepts to be explored such as atomic scale friction, surface – adsorbate potential energy landscapes, bound state resonances and quantum tunnelling rates. [3,4]

Microscopy has been a major enabling technique for the development and understanding of materials from the bottom up. Some of the major insights in the development of modern materials have come from scanning probe, electron and ion microscopies, with advances in resolution and sensitivity enabling new material science. Unfortunately charged beam techniques tend to cause surface damage and scanning probe techniques are limited to relatively flat surfaces and suffer from limited scan speeds.

In 2013, in collaboration with colleagues at the University of Newcastle, NSW, I have measured some of the first reflective mode images with a neutral helium beam [5,6]. In comparison with a charged beam microscope, the instrument delivers uniquely surface sensitive images with atomic resolution and critically produces no surface damage. Helium microscopy is suitable for measuring a variety of samples including insulator, semiconductor, explosive, biological and 3D self-assembled materials and being a real space technique does not involve complicated post processing techniques. Since generating the first images, I have been working on the contrast mechanisms that the technique affords, while developing the instrument to increase sensitivity and resolution with the objective of commercially viable instrument in the short term.

[1] D. J. Ward et al. Physical Review Letters 105 2010

[2] E.M. McIntosh et al Chem. Sci. 5 ,667-676 2014

[3] E.M. McIntosh et al. Phys. Rev. Lett. 110, 086103, 2013.

[4] Lechner, B.A.J., et al. Angew. Chemie – Int. Ed., 52 (19), pp. 5085‐5088, 2013.

[5] D.J. Ward et al. Nature Communications, 10.1038/ncomms10189 in press.

[6] D.J. Ward et al. Nucl. Instr. Meth. Phys. Res B 340 76-80, 2014.

David Ward

Experimental surface science with helium beams; microscopy and spectroscopy for imaging and dynamics measurement

Helium atom beams have been exploited in surface science investigations because they can be formed into controllable beams, have immense surface sensitivity and a small enough wavelength for high resolution studies. In the talk I will cover the use of Helium beams in my research, both in measuring dynamics with the Surface spin-echo spectrometer, and then introduce the latest instrument in the helium scattering family: A neutral beam helium atom microscopy, which I have developed.

The helium spinecho instrument measured its first spectra in 2005, and since then has been used to investigate a wide range of processes and systems, from quantum motion of hydrogen [1] to more complex molecules such as Ionic Liquids [2]. The strength of the technique allows a variety of dynamical concepts to be explored such as atomic scale friction, surface – adsorbate potential energy landscapes, bound state resonances and quantum tunnelling rates. [3,4]

Microscopy has been a major enabling technique for the development and understanding of materials from the bottom up. Some of the major insights in the development of modern materials have come from scanning probe, electron and ion microscopies, with advances in resolution and sensitivity enabling new material science. Unfortunately charged beam techniques tend to cause surface damage and scanning probe techniques are limited to relatively flat surfaces and suffer from limited scan speeds.

In 2013, in collaboration with colleagues at the University of Newcastle, NSW, I have measured some of the first reflective mode images with a neutral helium beam [5,6]. In comparison with a charged beam microscope, the instrument delivers uniquely surface sensitive images with atomic resolution and critically produces no surface damage. Helium microscopy is suitable for measuring a variety of samples including insulator, semiconductor, explosive, biological and 3D self-assembled materials and being a real space technique does not involve complicated post processing techniques. Since generating the first images, I have been working on the contrast mechanisms that the technique affords, while developing the instrument to increase sensitivity and resolution with the objective of commercially viable instrument in the short term.

[1] D. J. Ward et al. Physical Review Letters 105 2010
[2] E.M. McIntosh et al Chem. Sci. 5 ,667-676 2014
[3] E.M. McIntosh et al. Phys. Rev. Lett. 110, 086103, 2013.
[4] Lechner, B.A.J., et al. Angew. Chemie – Int. Ed., 52 (19), pp. 5085‐5088, 2013.
[5] D.J. Ward et al. Nature Communications, 10.1038/ncomms10189 in press.
[6] D.J. Ward et al. Nucl. Instr. Meth. Phys. Res B 340 76-80, 2014.

Oliver Lomax

The Role of Discs in the Collapse and Fragmentation of Prestellar Cores

Disc fragmentation provides an important mechanism for producing low mass stars in prestellar cores. Here, we describe Smoothed Particle Hydrodynamics simulations which show how populations of prestellar cores evolve into stars. We find the observed masses and multiplicities of stars can be recovered under certain conditions.

First, protostellar feedback from a star must be episodic. The continuous accretion of disc material on to a central protostar results in local temperatures which are too high for disc fragmentation. If, however, the accretion occurs in intense outbursts, separated by a downtime of ~10^4 years, gravitational instabilities can develop and the disc can fragment.

Second, a significant amount of the cores’ internal kinetic energy should be in solenoidal turbulent modes. Cores with less than a third of their kinetic energy in solenoidal modes have insufficient angular momentum to form fragmenting discs. In the absence of discs, cores can fragment but results in a top heavy distribution of masses with very few low mass objects.

Name

Title

abstract

Serban Lepadatu

Interaction of Electrical Currents and Magnetisation in Magnetic Nano-Structures

Here I will discuss the phenomenon of current-induced domain wall movement, using both experimental and theoretical results. In particular I will review results on determination of non-adiabaticity of spin-transfer-torque, design of harmonic domain wall oscillators and implementation in a planar magnetic memory cell, as well as applications of multi-layered synthetic anti-ferromagnetic structures. Finally, I will introduce a new micromagnetics model, developed at UCLan, for field and current-induced domain wall movement studies in realistic magnetic nano-structures.

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Judith de Patoul

3D electron density distributions in the solar corona during solar minima: assessment for more realistic solar wind modeling

The distribution of the magnetic field generated in the solar interior and connected into the solar wind influences most coronal phenomena including large-scale and slowly evolving coronal structures. Knowledge of the electron density distribution in the solar corona can serve as a tracer of the configuration of the coronal magnetic field and provide constraints on the field configurations for coronal modelling as well as on initial conditions for solar wind modelling. We work with polarized SOHO/LASCO-C2 images from the last two recent minima of solar activity (1996-1997 and 2008-2010), devoid of coronal mass ejections. We derive the 4D electron density distributions in the corona by applying a newly developed time-dependent tomographic reconstruction method. First, we compare the results with both a polytropic and thermodynamic MHD models. Second, we study the temporal variation with the solar cycle in the polar and equatorial regions during the two solar minima. Finally, we focus on the highest-density structures and measure their differential rotation well above the surface. Such valuable information on 4D electron density distributions and large-scale structures could help to connect the sources of the solar wind to their in situ counterparts in future missions such as Solar Orbiter and Solar Probe Plus.

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Sergei Nayakshin

Exoplanet observations overturn classical ideas about the Solar System formation

Some 40 years ago, observations of the Solar System and environments in which stars form helped to set the classical paradigm of how planets form. Core Accretion theory stipulates that planets are made in a way distinct from anything else in Astronomy, by first forming km-sized rocks and then gently collecting them together into larger and larger solid cores. When the cores exceed the mass of ~ ten Earth masses, hydrogen finally starts to accrete onto the planet, forming gas giant planets such as Jupiter. Observations of the last two decades uncovered thousands of exoplanets, many found in environments previously thought unthinkable for planet formation. I show that many of these observations contradict Core Accretion theory strongly. I review a new planet formation theory born around 2010 in which planets start forming as stars and galaxies, by gravitational collapse of a protoplanetary gas disc, but then take a different route due to a lack of gas supply and the domineering presence of their host stars. I show how this theory may explain the structure of both the Solar System and the exoplanetary systems, and summarise future observational predictions to distinguish it from the classical scenario.

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Melvin Vopson

Future technologies based on multiferroic materials

The recent surge of interest in multiferroic materials has been driven by their fascinating physical properties, as well as their huge potential for technological applications. Materials science is a key factor in driving development and economic growth. Since the silicon industrial revolution of the 1950s, research and developments in materials science have radically impacted and transformed our society through the emergence of computer technologies, wireless communications, Internet, digital data storage technologies and widespread consumer electronics. Today’s emergent topics in materials science research such as nano-materials, carbon based grapheme and nano-tubes, smart and multifunctional materials, spintronic materials, bio-materials and multiferroic materials, promise to deliver a new wave of technological advances and economic impact, comparable to the silicon industrial revolution of the 1950s.

The potential applications of multiferroic materials cover a wide range of technologies. In this lecture, Dr Vopson presents a short introduction into the physics of multiferroic materials and the recently discovered multicaloric effect, followed by a detailed description of one of their interesting potential applications to refrigeration industry.

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First Year PhD Student Talks

  • Aaron Brocklebank: Investigating Massive Stars and Supernovae
  • Zoe Henderson: Probing Surface Structure and Interactions of Ionic Liquids
  • Tom Kirk: The link between Model Theoretic and Topological invariants
  • Adam Knowles: Stellar Population Modelling
  • Anthony Mercer: The Thermal History of Protostellar Disks

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Colm Coughlan

New discoveries at low frequencies – Observing Young Stellar Objects at 150 MHz with LOFAR

Young Stellar Objects (YSOs) are visible at radio frequencies due to thermal emission from their disks and outflows, as well as non-thermal emission from shocked regions in their jets. At the lowest frequencies thermal free-free emission from outflows dominates over emission from the disk/envelope. Identifying the turnover frequency where this emission transitions from optically thin to optically thick can be used to constrain important physical parameters of the system, such as the mass of local ionized gas and the emission measure of local plasma. I will present observations of three YSOs, T Tau, DG Tau and L1551 IRS 5, taken with the GMRT at 323 and 608 MHz and discuss implications for the turnover frequencies and properties of these YSOs. I will also present the latest results from LOFAR observations of T Tau at 150 MHz.

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Vasilis Archontis

Our active Sun: magnetic fields, jets and eruptions

The activity on the Sun that influences life on Earth is mainly driven by the emergence of magnetic fields (EMF) on a variety of temporal/spatial scales. The process of EMF can lead to the formation of Active Regions and the onset of explosive events, such as jets and eruptions of fast magnetized plasma (e.g. Coronal Mass Ejections). We will present an overview of recent advances and future challenges regarding the manifestation of solar magnetic activity driven by magnetic flux emergence.

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Philipp Niklowitz

Spin-density wave masking a ferromagnetic quantum-critical point in NbFe2

Many experimental and theoretical studies suggest that it is difficult to approach ferromagnetic quantum critical points in real materials. Instead, a variety of escape routes have been observed, notably the occurrence of a first order transition or superconductivity. The bulk properties of NbFe2 suggest a third scenario: marginal Fermi liquid behaviour as expected of a quantum critical point is detected in thermodynamic and transport measurements [1], but the ferromagnetic quantum critical point itself appears to be masked by modulated magnetic order [2].

In this seminar neutron diffraction results will be presented, which directly show that the ferromagnetic quantum critical point in NbFe2 is masked by a spin-density-wave phase. An overview will be given of inelastic neutron scattering data with a focus on low-energy magnetic excitations present in this system. It will be discussed, in which way the magnetic excitations of NbFe2 reflect the simultaneous proximity to two types of magnetic order.

  • [1] M. Brando et al., Phys. Rev. Lett. 101 (2008) 026401
  • [2] D. Rauch et al., Phys. Rev. B 91 (2015) 174404

Philipp Niklowitz

Spin-density wave masking a ferromagnetic quantum-critical point in NbFe2

Many experimental and theoretical studies suggest that it is difficult to approach ferromagnetic quantum critical points in real materials. Instead, a variety of escape routes have been observed, notably the occurrence of a first order transition or superconductivity. The bulk properties of NbFe2 suggest a third scenario: marginal Fermi liquid behaviour as expected of a quantum critical point is detected in thermodynamic and transport measurements [1], but the ferromagnetic quantum critical point itself appears to be masked by modulated magnetic order.[2]

In this seminar neutron diffraction results will be presented, which directly show that the ferromagnetic quantum critical point in NbFe2 is masked by a spin-density-wave phase. An overview will be given of inelastic neutron scattering data with a focus on low-energy magnetic excitations present in this system. It will be discussed, in which way the magnetic excitations of NbFe2 reflect the simultaneous proximity to two types of magnetic order.

  • M. Brando et al., Phys. Rev. Lett. 101 (2008) 026401
  • D. Rauch et al., Phys. Rev. B 91 (2015) 174404

Phil James

Studies of star formation and supernova progenitors in nearby galaxies

Recent years have seen a proliferation in the discovery rates of supernovae, resulting in an ever-increasing number of types of stellar explosion that are now recognised. I will describe recent developments in the attempt to determine properties of the progenitor stars that lead to these different types of explosion, through observations of the galaxy environment local to the explosion. I will conclude with a discussion of the use of core-collapse supernovae as direct probes of star formation, and look forward to prospects for this field when the LSST project comes to fruition.

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Gareth Few

Chemical Evolution with Supercomputers: Hydrodynamics and Globular Clusters

The complex interplay between the dynamics of gas and stars and the evolution of the elemental composition of the universe is best modelled with numerical methods, requiring the use of high performance computers. I will explain how to use chemodynamical simulations to understand chemical evolution in globular clusters and what that tells us about their formation. I will also describe how, despite recent advances in the field, not all hydrodynamical methods are equal.

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Carole Mundell

Black hole driven explosions and the dynamic Universe

Black-hole driven processes in the Universe are now accepted to play a key role in the evolution – perhaps even formation – of galaxies, the cataclysmic death of massive stars and ultimately the production of long-sought detected gravitational waves. In this talk, I will present recent studies of stellar and supermassive black holes systems; I will show the uniquity of fast outflows, the importance and role of magnetic fields and present prospects for future work with existing and upcoming facilities working across the electomagnetic spectrum and into the time domain.

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Jochen Koenigsmann

On rational numbers

“Rational numbers are easier to handle than real numbers because with rationals you can only do algebra, whereas the reals lead you straight into calculus, differential equations, integrals and other tough business.”

We will contrast this widespread view with the by now well understood phenomenon that the algebra of the reals is much easier than the algebra of the rationals. To illustrate this, we will present two big open problems about the rationals (one along the lines of Hilbert’s 10th problem, the other going back to Grothendieck’s “anabelian geometry”), explaining very recent progress towards their solution.

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Jenny Hatchell

Taking the temperature of local star-forming clouds with the JCMT Gould Belt Survey

Radiative heating by recently-formed (or forming) stars potentially provides a regulatory mechanism for star formation, reducing fragmentation and increasing protostellar masses. I will report on work carried out by the JCMT Gould Belt survey team on the contribution that SCUBA-2 data makes to measuring dust temperatures, on its own and in combination with Herschel measurements.

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Tom Marsh

Magnetic white dwarfs and a star like no other

White dwarfs, the compact remnants of most stars, can have magnetic fields as high as 100,000 Tesla which can dramatically alter their spectra and their environments when they accrete within binary stars. I will review the known types of magnetic white dwarf and accreting white dwarf, and discuss problems concerning the origin of the fields. I will then spend the rest of the talk on an extraordinary new magnetic white dwarf in a binary which emits over the whole observable electromagnetic spectrum and may be a white dwarf analogue of milli-second pulsars.

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Ding Yuan

Sunspot oscillations and seismology

Magnetohydrodynamic waves interact with the Sun’s magnetic structures and reveals their fine structures. By analysing MHD waves, we are able to diagnose the Sun’s local plasma parameters, e.g. magnetic field, transport coefficients, remotely. Sunspots and active regions are hosts of multiple MHD wave modes. In this study, we investigate how a sunspot’s fine magnetic topologies affect MHD waves and propose the associated seismological applications.

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Nina Dresing

Anisotropies of solar energetic particle events

Solar energetic particles (SEPs) are charged particles which are accelerated to high energies at so-called solar flares or at shock fronts, associated to solar eruptions. A certain fraction of the accelerated particles can leave the Sun and propagate through the interplanetary medium until the Earth’s orbit and beyond. Some of the SEP events are so energetic and intensive that they can be measured even on the Earth’s surface and are subject to space weather. To characterize or event forecast such events it is indispensable to understand not only the acceleration processes but also the particle transport through the inner heliosphere.

The anisotropy of a particle distribution provides a measure of how beamed the distribution is. Therefore, the anisotropy is a key characteristic of an SEP event and important to determine the amount of scattering the particles experienced during their propagation through the interplanetary medium. Especially during multi-spacecraft SEP events with wide angular particle distributions the anisotropy can give insights on the the relative importance of transport versus injection effects.

The determination, limitation and interpretation of anisotropies will be discussed by means of measurements by the Solar Electron and Proton Telescope (SEPT) aboard the two STEREO spacecraft as well as close to Earth observations.

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Petri Vaisanen

Worth its SALT: recent science from the Southern African Large Telescope

UCLAN is a member in the SALT consortium operating a 10-m class optical telescope in South Africa. SALT is in its first years of science operations, and has seen strong increase in science output making it perhaps the world’s most cost-effective large telescope. I will give a brief description of the project with recent updates and highlights. I will then describe my own research using SALT, involving star-forming galaxies, their super star cluster populations, and galaxy-wide winds affecting the evolution of these systems.

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Rosemary Wyse

The Structure and Substructure of the Disks and Halo of the Milky Way Galaxy

I will present some recent results pertaining to our current understanding of the structure and substructure of the stellar disks and halo of the Milky Way and the insight gained into Galaxy evolution. In particular, I will discuss new analyses of the separation into thin and thick discs and the role of radial migration in the evolution of the thin disc. Turning to the stellar halo, I will discuss our investigations into the evolution of tidal streams from disrupting stellar systems in a triaxial dark halo (Via Lactae II), together with the implications for detection of streams and for identification of gaps that could be formed by dark subhaloes.

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Gareth Boxall

Complex Exponentiation

I shall discuss the structure Cexp which consists of the set C of complex numbers together with the operations of addition and multiplication and the exponential function exp(z) = ez. A polynomial is anything that can be formed from variables and complex numbers using the operations of addition and multiplication. An exponential polynomial is anything that can be formed from variables and complex numbers using addition, multiplication and the function exp. The study of Cexp inevitably involves the study of exponential polynomials. I shall discuss these with reference to what is known about polynomials.

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Will Clarkson

Maximizing Galactic science from LSST

The Large Synoptic Survey Telescope (LSST) will be a truly remarkable survey machine. With a 6.7m effective aperture and a huge 9.6 square-degree field of view (imaged at 0.2 arcseconds per pixel in ugrizy filters), it will provide a seeing-limited imaging survey of about 30,000 square degrees of the sky to depth roughly r~24.5 per image (or a co-added map down to r~27.5 over the total ten-year time baseline). While LSST’s design is led by its main four science drivers, a huge range of science cases will benefit from repeated imaging by a 6m-class telescope optimized for superb astrometry and photometry.

With first light expected before the end of this decade, the critical process of setting LSST’s detailed observing strategy is now underway. Particularly in spatial regions outside the main survey area, the “best” survey strategy remains undetermined, and community input is needed. This represents an opportunity to advance many areas of observational astronomy. A large effort has begun, to quantitatively assess the value to the various science cases of proposed observing cadences and strategies. This development is being performed entirely “in the open” via GitHub, and currently comprises about eighty members of the astronomical community.

I will present the current status and plans of this remarkable collaborative effort, with particular focus on maximizing LSST’s use for advancing our understanding of the Milky Way galaxy and the populations within it. For a number of science cases, small changes in strategy can have transformative effects on LSST’s utility for Galactic science. I will highlight areas in which community input is needed, and opportunities to get involved to help ensure that LSST advances your science.

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John Kormendy

Structure and formation of S0 and spheroidal galaxies

We present observational evidence that Sph galaxies such as Fornax and NGC 205 are bulgeless S0 galaxies. Both are late-type galaxies that have been transformed into gas-free, red and dead galaxies by a variety of internal and environmental processes.

We update van den Bergh’s parallel sequence galaxy classification in which S0 galaxies form a sequence S0a-S0b-S0c that parallels the sequence Sa-Sb-Sc of spiral galaxies. The ratio B/T of bulge to total light defines the position of a galaxy in this tuning fork diagram. Our classification makes a major improvement: We extend the S0a-S0b-S0c sequence to spheroidal (Sph) galaxies that are positioned in parallel to irregular galaxies in a similarly extended Sa-Sb-Sc-Im sequence. This provides a natural home for spheroidals, which previously were thought to be low-surface-brightness ellipticals. To motivate our juxtaposition of spheroidals and irregulars, we present photometry and bulge-disk decompositions of late-type S0s that bridge the gap between the more common S0b and Sph galaxies. We find several S0s in the Virgo cluster that have B/T <= 0.1. They are the S0cs that were missing from van den Bergh's paper. We update the structural parameter correlations of Sph, spiral, irregular, and elliptical galaxies. We show that spheroidals of increasing luminosity form a continuous sequence with the disks (but not bulges) of S0c-S0b-S0a galaxies. Remarkably, this Sph-S0-disk sequence is almost identical to that of irregular and spiral galaxies. We review the evidence for a variety of physical processes which we suggest transform gas-rich, star-forming S+Im galaxies into gas-poor S0+Sph galaxies.

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Mikko Tuomi

Planets orbiting M dwarfs in the Solar neighbourhood

The most numerous stars in the galaxy, M dwarfs, are also the most common stellar types in the Solar neighbourhood. As radial velocity studies of planets are relatively easier due to their lower massess giving rise to radial velocity signals of higher amplitudes and thus easier detectability, M dwarfs also appear to be hosts to more planets than brighter FGK stars. Whereas Kepler spacecraft has covered radius-space and short orbital periods, we cover the mass-space and period space up to ~5000 days with radial velocities to study the occurrence rate of planets orbiting M dwarfs. Our results agree with those obtained with Kepler transit photometry: there are, on average, more than 2.5 planets orbiting M dwarfs and they are thus very commonly planet hosts, even amongst the nearest stars to the Sun such as Proxima Centauri.

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Mihalis Mathioudakis

Spectropolarimetry of small-scale solar structures in the era of large aperture solar telescopes

The solar atmosphere provides a working example where complex structures and dynamics can be studied over an enormous range of spatial and temporal scales. While we are only able to catch glimpses of these processes and phenomena in other astrophysical sources, the Sun provides a vantage reference point where the complex interplay between the plasma and the magnetic field is visible and can be studied continuously with unprecedented detail. I will focus on the smallest observable structures on the Sun’s atmosphere and highlight the physical parameters that we can derive by means of spectropolarimetry. I will dedicate a significant part of the seminar to the 4m DKI Solar Telescope which will provide ultra-high spatial (25 km on the solar surface) and temporal resolution (millisecond), imaging spectroscopy (200,000) and coronal magnetometry. I will use specific science cases to highlight its instrument capabilities and emphasize the significance of the UK contribution for this facility.

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Hem Raj Sharma

Templated Quasicrystals of Single Elements and Molecules

Quasicrystals are intermetallic compounds possessing long range order without periodicity. Quasi-crystalline phases have been found in various materials from metallic alloys, polymers to oxides. Being different from periodic crystals, alloy quasicrystals are promising for the exploration of new epitaxial phenomena. We present several interesting epitaxial results observed on the icosahedral Ag-In-Yb quasicrystal, which is built by rhombic triacontahedral (RTH) clusters. The results include three dimensional quasicrystalline films of single elements [1], quasicrystalline molecular films [2] and fivefold-twinned islands with magic heights influenced by quantum size effects [3].

Using scanning tunnelling microscopy (STM) and density functional theory (DFT) calculations of adsorption energies, we find that lead atoms deposited on the fivefold surface of i-Ag-In-Yb occupy the positions of atoms in the RTH cluster and thus produce quasicrystalline film in three-dimension [1]. This observation is evidenced in other systems as well, namely Pb on the threefold i-Ag-In-Yb and In, Sb and Bi on the fivefold i-Ag-In-Yb surface. We also found that Pentacene molecules adsorbs at tenfold-symmetric sites of Yb atoms around surface-bisected RTH clusters, yielding quasicrystalline order [2]. Similarly, C60 growth on the fivefold surface of i-Al-Cu-Fe at elevated temperature produces quasicrystalline layer, where the growth is mediated by Fe atoms on the surface [3]. The compatibility between the characteristic lengths of the substrate and the size of adsorbates has led to a growth of unprecedented epitaxial structures.

The finding of quasicrystalline thin films of single elements and molecules opens an avenue for further investigation of the impact of the aperiodic atomic order over periodic order on the physical and chemical properties of materials.

This work was done in collaboration between the University of Liverpool, Tohoku University Japan, Chuo University Tokyo and University of Central Lancashire.

[1] H. R. Sharma, K. Nozawa, J. A. Smerdon, P.J. Nugent, I. McLeod, V. R. Dhanak, M. Shimoda, Y. Ishii, A.P. Tsai and R. McGrath, Nature Communications 4, 2715 (2013)
[2] J. A. Smerdon, K. M. Young, M. Lowe, S. S. Hars, T. P. Yadav, D. Hesp, V. R. Dhanak, A. P. Tsai, H. R. Sharma and R. McGrath, Nano Letters 14, 1184 (2014)
[3] H. R. Sharma, J. A. Smerdon, P. J. Nugent, A. Ribeiro, I. McLeod, V. R. Dhanak, M. Shimoda, A. P. Tsai, and R. McGrath, The Journal of Chemical Physics 140, 174710 (2014)

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Emily Drabek-Maunder

HCO+ Detection of Dust-Depleted Gas in the Inner Hole of the LkCa 15 Pre-Transitional Disk

LkCa 15 is an extensively studied star in the Taurus region known for its pre-transitional disk with a large inner cavity in dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes one or more planets to carve out the inner cavity, while gas continues to flow across the gap from the outer disk onto the central star. We present spatially unresolved HCO+ J=4-3 observations of the LkCa 15 disk from the JCMT and model the data with the ProDiMo code. We find that: (1) HCO+ line-wings are clearly detected, certifying the presence of gas in the cavity within < 50 AU of the star. (2) Reproducing the observed line-wing flux requires both a significant suppression of cavity dust (by a factor > 104 compared to the ISM) and a substantial increase in the gas scale-height within the cavity (H0/R0 ~ 0.6). An ISM dust-to-gas ratio (d:g=10-2) yields too little line-wing flux regardless of the scale-height or cavity gas geometry, while a smaller scale-height also under predicts the flux even with a reduced d:g. (3) The cavity gas mass is consistent with the surface density profile of the outer disk extended inwards to the sublimation radius (corresponding to mass Md ~ 0.03 M), and masses lower by a factor > 10 appear to be ruled out.

Emily Drabek-Maunder

HCO+ Detection of Dust-Depleted Gas in the Inner Hole of the LkCa 15 Pre-Transitional Disk

LkCa 15 is an extensively studied star in the Taurus region known for its pre-transitional disk with a large inner cavity in dust continuum and normal gas accretion rate. The most popular hypothesis to explain the LkCa 15 data invokes one or more planets to carve out the inner cavity, while gas continues to flow across the gap from the outer disk onto the central star. We present spatially unresolved HCO+ J=4-3 observations of the LkCa 15 disk from the JCMT and model the data with the ProDiMo code. We find that: (1) HCO+ line-wings are clearly detected, certifying the presence of gas in the cavity within < 50 AU of the star. (2) Reproducing the observed line-wing flux requires both a significant suppression of cavity dust (by a factor > 104 compared to the ISM) and a substantial increase in the gas scale-height within the cavity (H0/R0 ~ 0.6). An ISM dust-to-gas ratio (d:g=10-2) yields too little line-wing flux regardless of the scale-height or cavity gas geometry, while a smaller scale-height also under predicts the flux even with a reduced d:g. (3) The cavity gas mass is consistent with the surface density profile of the outer disk extended inwards to the sublimation radius (corresponding to mass Md ~ 0.03 M&sun;), and masses lower by a factor > 10 appear to be ruled out.

Ralph Schoenrich

Disk galaxy evolution in the era of Gaia

I will discuss recent advances in chemodynamic models of disc galaxies, and how we can use them to understand data from Gaia and its follow-up spectroscopic surveys. The complexity of the data and the theoretical problem prevents us from directly comparing to N-body/hydrodynamics simulations, but we can use these to infer analytical laws to describe e.g. secular heating of stellar populations, and measure these using analytical chemodynamic models. I will address the origin of the galactic discs and history of the Milky Way, discuss radial migration, secular heating processes and the question of inside-out formation. Also, radial mixing has surprising consequences for galactic chemical evolution, and I will show how observations from the nuclear disc and throughout the galaxy will help us to constrain chemical evolution models.

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Title

abstract

George Bendo

Measuring Star Formation Rates Using the Atacama Large Millimeter/submillimeter Array (ALMA)

The Atacama Large Millimeter/submillimeter Array (ALMA), located at high altitude in Chile, has greatly advances research in millimetre and submillimetre astronomy since it began performing science observations five years ago. While the telescope has been used mainly to observe molecular gas and dust, ALMA can also detect both the Bremsstrahlung continuum and hydrogen spectral line emission from the photoionized gas associated with star forming regions within nearby galaxies. These forms of millimetre emission can be used to calculate highly accurate star formation rates, as the emission is uaffected by dust obscuration and as it directly associated with the star forming regions themselves. Star formation rates from ALMA data have been used to identify the strengths and weaknesses of star formation tracers in other parts of the electromagnetic spectrum, including the surprising result that infrared emission from interstellar dust may be a highly inaccurate star formation tracer in nearby starburst galaxies and potentially more distant starburst galaxies as well.

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Title

abstract

Giovanni Costantini

Molecular self-assembly as a means to understand charge transfer at metal-organic interfaces

Most applications in organic electronics and organic photovoltaics require the deposition of a thin molecular film onto conductive electrodes. The growth of the first few molecular layers represents a crucial step in the device fabrication since the organic-electrode interface carries the entire device functionality. Nevertheless, the ability to rationally tune and modify the electronic configuration of these systems is extremely limited because the energy level alignment at metal-organic interfaces is influenced by a complex combination of factors. As a result, most work in the field is still based on a trial-and-error approach.

In this talk I will present a new method to investigate the formation of metal-organic interfaces based on studying the relation between molecule-substrate charge transfer and the development of specific molecular assembly patterns. In particular, I will show that the driving force for charging an individual molecule depends not only on the position of its frontier orbitals with respect to the substrate Fermi level, but also on the electrostatic interaction with its local neighbours’ environment. The resulting interplay of long-range attractive or repulsive forces acting between interfacial molecular dipoles and short-range attractive interactions, determines the emergence of peculiar assembly patterns that are a direct consequence of the local electronic configuration.

Using a series of ad-hoc designed molecules I will show that combining scanning tunnelling microscopy and spectroscopy with atomistic simulations allows to study the elementary processes responsible for the observed self-assembly behaviour. The talk will focus on molecules characterised by anomalous coarsening caused by reversible charge transfer [1] and on two-component systems where specific co-assembly patterns result from the electron accepting behaviour of one molecule being selectively induced by the presence of the other [2].

[1] A. Della Pia et al., ACS Nano 8, 12356 (2014)
[2] A. Della Pia et al., submitted.

Giovanni Costantini

Molecular self-assembly as a means to understand charge transfer at metal-organic interfaces

Most applications in organic electronics and organic photovoltaics require the deposition of a thin molecular film onto conductive electrodes. The growth of the first few molecular layers represents a crucial step in the device fabrication since the organic-electrode interface carries the entire device functionality. Nevertheless, the ability to rationally tune and modify the electronic configuration of these systems is extremely limited because the energy level alignment at metal-organic interfaces is influenced by a complex combination of factors. As a result, most work in the field is still based on a trial-and-error approach.

In this talk I will present a new method to investigate the formation of metal-organic interfaces based on studying the relation between molecule-substrate charge transfer and the development of specific molecular assembly patterns. In particular, I will show that the driving force for charging an individual molecule depends not only on the position of its frontier orbitals with respect to the substrate Fermi level, but also on the electrostatic interaction with its local neighbours’ environment. The resulting interplay of long-range attractive or repulsive forces acting between interfacial molecular dipoles and short-range attractive interactions, determines the emergence of peculiar assembly patterns that are a direct consequence of the local electronic configuration.

Using a series of ad-hoc designed molecules I will show that combining scanning tunnelling microscopy and spectroscopy with atomistic simulations allows to study the elementary processes responsible for the observed self-assembly behaviour. The talk will focus on molecules characterised by anomalous coarsening caused by reversible charge transfer [1] and on two-component systems where specific co-assembly patterns result from the electron accepting behaviour of one molecule being selectively induced by the presence of the other [2].

[1] A. Della Pia et al., ACS Nano 8, 12356 (2014)
[2] A. Della Pia et al., submitted.

Rob Crain

Cosmological hydrodynamical simulations of the galaxy population

I will briefly recap the motivation for, and progress towards, numerical modelling of the formation and evolution of the galaxy population – from cosmological initial conditions at early epochs through to the present day. I will introduce the EAGLE project, a flagship program of such simulations conducted by the Virgo Consortium. These simulations represent a major development in the discipline, since they are the first to broadly reproduce the key properties of the evolving galaxy population, and do so using energetically-feasible feedback mechanisms. I shall present a broad range of results from the 18 months of EAGLE analyses, concerning the evolution of galaxy masses, their luminosities and colours, and their atomic and molecular gas content, to convey some of the strengths and limitations of the current generation of numerical models.

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Title

abstract

Tim Horbury

The solar wind near the Sun

The solar wind is a variable, continuous plasma outflow from the Sun that fills all space and causes ‘space weather’ effects, both good – the aurora borealis – and bad – power grid failures, satellite problems, radiation hazards for astronauts. By the time it reaches the Earth, the solar wind is heavily modified compared to its original state. If we are to understand how it is created, we need to measure it closer to the Sun. We last explored the inner solar wind in the 1970?s with the twin Helios spacecraft, but we are going back: Solar Orbiter and Solar Probe Plus will both launch in 2018 to explore this region.

I will show a recent discovery, in the 40-year-old Helios data, or remarkable 1000km/s jets in the solar wind, and discuss their origin. I will also present Solar Orbiter and the current status of one of its instruments, the magnetometer, which is being built at Imperial College.

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Title

abstract

Shu-ichiro Inutsuka

Filaments, Shells, and Bubbles: Toward a Galactic View of Star Formation

We propose a unified picture of star formation in the Galaxy. Recent high-resolution magneto-hydrodynamical simulations of two-fluid dynamics with cooling/heating and thermal conduction have shown that the formation of molecular clouds requires multiple episodes of supersonic compression. This finding enables us to create a new scenario of molecular cloud formation as the interacting shells or bubbles in galactic scale, which explains various observational properties such as cloud-to-cloud velocity dispersions, emergence of filamentary structure, accelerating star formation, and very low star formation efficiencies. We estimate the ensemble-averaged growth rate of individual molecular clouds, and predict the associated cloud mass function. The recent claim of cloud-cloud collisions as a mechanism for forming massive stars and star clusters can be naturally accommodated in this scenario. This explains why massive stars formed in cloud-cloud collisions follows the power-law slope of the mass function of molecular cloud cores repeatedly found in low-mass star forming regions.

Name

Title

abstract

Maciej Koprowski

IR Luminosity Function to z=4.5 from JCMT and ALMA

The Luminosity Function (LF), giving a number of sources of a given luminosity per unit volume at a given redshift, is a very powerful tool, allowing, amongst many other, the calculation of the Star Formation Rate Density (SFRD), one of the most fundamental observables in the astrophysical cosmology. In order to account for all the star formation at a given redshift however, we must look not only at the rest-frame UV (where the most massive stars emission peaks), but also at the far-IR/sub(mm) wavelengths (where a large fraction of the starlight absorbed by the dust is reemitted as heat). Determining LFs at UV/optical has been performed for over two decades and redshifts as high as 10 have been reached. In the far-IR/sub(mm) regime, the process is much more complicated, mainly due the atmosphere absorption and the large beam sizes, and indeed the reliable estimates of the IR LFs extend only to redshifts of about 2. In this talk I will present the recent work done with the JCMT SCUBA2 850um data collected as part of a recently-finished SCUBA2 Cosmology Legacy Survey and the first ever ALMA blank-field sky survey of the Hubble Ultra Deep Field. I will explain how the functional forms of the IR LFs have been established and used, with the recently-calculated UV LFs, to determine the total SFRD over redshifts 0.5 to 4.5.

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