Dejan Vinković & Bojan Pečnik
Title: A QUEST TO PSEUDO-SATELLITES
It has been more than two decades of efforts to develop a commercially sustainable civilian concept of an unmanned aerial system (UAS) that could persistently perform airborne operations for days, weeks, or months. The attractiveness of this idea comes from a range of business opportunities that would open thanks to a long-endurance high-resolution hyper-spectral aerial presence over a designated area. Massive contemporary use of military-grade, high/medium-altitude long-endurance (HALE/MALE) surveillance UAS technologies, has given a false sense of feasibility for such a concept in the civilian sector. In effort to establish a commercial non-military sustainable pseudo-satellite foothold in the stratosphere, this false sense of feasibility led to a series of very expensive and public failures. We will discuss what role physics and environment play in these efforts, and how this led our company to target mid-troposphere to reach the equivalent functionality in the skies by using the HiperSfera aircraft, an un-manned airship-drone hybrid. We will be presenting HiperSfera’s Persistent Aerial Positioning as a Service (PAPaaS) vision for the future skies and will be discussing societal and business opportunities that can open thanks to our technology.
Jim Wild
Title: Extreme magnetic field disturbances and their role in space weather impacts
Some of the most significant terrestrial impacts of space weather are rapid, large-amplitude fluctuations in the magnetic field at the Earth’s surface. These fluctuations can induce a geoelectric field in the Earth and cause electrical currents – Geomagnetically Induced Currents (GIC) – to flow in conducting structures grounded in the Earth. GICs are therefore a potential hazard to industrial networks, such as railways, metal oil, and gas pipelines, and high-voltage electrical power grids, during severe space weather. This seminar will highlight several recent streams of research at Lancaster University, including a new global climatological model of extreme geomagnetic field fluctuations, and exploration of the impact of GIC on power-generating and rail transport infrastructure in the North West region and beyond.
Martin Wheatman
Title: Speech is the Universal Machine: programming in natural language
Why is there no spoken user interface? This talk explains how the analysis of writing–aka Structuralism–has been used to model the spoken word throughout the 20th Century. Since computer software is a written medium, this has impeded the development of general speech understanding: smart speaker systems use speech simply as triggers for preprogrammed action. By applying the philosophy of Pragmatism, as a recursive model of information, speech can be used to describe speech which exposes instruction, removing the need for syntax and semantics.
Rob Crain
Title: The coupled roles of halo assembly history, black hole growth and circumgalactic gas expulsion in governing galaxy evolution
I will present results from several suites of cosmological hydrodynamical simulations, which indicate that the evolution of simulated present-day ~L* central galaxies is markedly influenced by the assembly history of their parent dark matter halo. In particular, galaxies hosted by early-forming haloes have preferentially lower specific star formation rates (often even being quenched), and less disky morphologies, than counterparts with late-forming haloes. The simulation show that early halo formation fosters the growth of more-massive central black holes (compared to late-forming haloes of similar present-day dynamical mass), and the extra feedback energy liberated by their growth depletes the circumgalactic medium of the efficiently cooling gas that would otherwise replenish interstellar gas consumed by star formation. A central prediction of this scenario is that the circumgalactic medium of quenched ~L* galaxies is of a lower density than that of star-forming counterparts, for which recent analyses of eROSITA X-ray data lend enticing support. I will also briefly show how controlled simulations, starting from “genetically modified” initial conditions, enable the influence of halo assembly history on galaxy evolution to be disentangled from large-scale environment effects.
Michael Buttery
Title: Tribology of spacecraft mechanisms: 48-million miles without an oil change
Spacecraft – be they scientific, communication, or earth observation – are not static, and contain numerous mechanisms and moving parts. Ensuring the good mechanical running of the spacecraft over years of operation in the hostile environment of space is a complex and challenging task for the space mechanism engineer, and one which must be considered very carefully. In many instances failure of a single mechanical system can result in failure of the entire mission.
This lecture shall introduce the field of vacuum and space tribology, discussing the challenges presented, their solutions, and some historic examples of tribological failures.
Julie Wardlow
Title: Understanding the environments of extreme dusty star-forming galaxies in the distant Universe
In recent years the high-redshift Universe has been increasingly opened to scrutiny at far-infrared wavelengths, where cool dust emission from star-formation dominates. The dusty star-forming galaxies (DSFGs), selected at these wavelengths likely represent an important, but short-lived phase in the growth of massive galaxies. These DSFGs often have star-formation rates in excess of ~1000 solar masses per year and are confirmed beyond z~6, although their redshifts and high dust contents make them faint and difficult to study at other wavelengths. I will explore DSFGs further and present data that probes their environments and triggering mechanisms to test whether they are the likely progenitors of local massive early-type galaxies
Ron Lifshitz
Title: What is a Crystal? A new paradigm for an old question
The discovery of quasicrystals signalled the beginning of a remarkable scientific revolution, in which some of the most basic notions of condensed matter physics and material science have undergone a thorough re-examination. Four decades later, the field continues to intrigue us with scientific puzzles, surprising discoveries, and new possibilities for applications. I will focus on some current issues from my own research – such as soft matter quasicrystals and photonic applications based on metamaterials – but only after giving a concise overview for non-specialists of what quasicrystals are, and why their discovery was so important.
Philippa Browning
Title: Modelling plasma heating, particle acceleration and oscillations in solar flares
Solar flares are dramatic releases of stored magnetic energy due to magnetic reconnection, leading to plasma heating and significant non-thermal populations of energetic electrons and ions. They can impact on the Earth and our space environment, and are integral to “space weather”.
I will describe some recent advances in modelling flares within twisted magnetic flux ropes, exploiting a combination of magnetohydrodynamic simulations to predict the thermal plasma and magnetic field evolution with test-particle modelling of the non-thermal population. The ideal kink instability in a flux rope leads to the formation of fragmented current sheets, in which magnetic reconnection can both heat plasma and efficiently accelerate particles. Forward-modelling of the observational signatures of these processes in EUV, hard X-rays and microwaves will be described. “Quasi-Periodic Pulsations” are a widely-observed phenomenon in flare emission, and I will show how these can arise a natural consequence of magnetic reconnection, in the absence of any external oscillatory driving, both in unstable twisted loops and in mergers of twisted flux ropes.
Extending the methodology to a data-driven approach, we model the evolution of fields, thermal plasma and non-thermal particles in actual flare events, successfully predicting key observational characteristics of the flare, such as the locations and relative intensities of hard X-ray sources. This allows investigation of the fraction of particles which escape into the heliosphere in different flares, and the relationship between the properties of escaping and precipitating particle populations, with consequences for understanding space weather.
Many other stars exhibit flares – often much more powerful than solar flares. To illustrate how our understanding of solar flares may be extended to other stars, some recent modelling of radio and X-ray emission from T-Tauri stars will be presented.
Ray Brederode
Title: Overview of the Square Kilometre Array Project
The Square Kilometre Array (SKA) project aspires to construct one of the largest science facilities ever built, an observatory with an unprecedented number of receivers across multiple continents. The SKA Observatory is designed to observe radio emmissions in unprecedented detail and enable transformational science. This seminar will take a brief look at the primary science cases, radio interferometry basics, telescope architecture and configuration, and project status.
Mingee Chung
Title: Quantum Magnetism in One Dimension
Quantum magnets represent the simplest of quantum many-body systems, which host a variety of exotic phases and transitions. They are magnetic insulators where spins on a lattice are coupled via exchange interaction. Since they have a simple and well-defined Hamiltonian, free from complication due to itinerant charges, a very close comparison between experiment and theory/calculation could be made. In this talk, following a step-by-step introduction to the field of Quantum Magnetism, I will present some experimental works on a quantum spin ‘ladder’ (one-dimensional quantum magnet), which are realized in molecular crystals. The main experimental technique is Nuclear Magnetic Resonance employed at milli-kelvin temperatures in a magnetic field up to 30 T, but a few other techniques such as heat capacity are also to be discussed.
Rob Crain
Title: The coupled roles of halo assembly history, black hole growth and circumgalactic gas expulsion in governing galaxy evolution
I will present results from several suites of cosmological hydrodynamical simulations, which indicate that the evolution of simulated present-day ~L* central galaxies is markedly influenced by the assembly history of their parent dark matter halo. In particular, galaxies hosted by early-forming haloes have preferentially lower specific star formation rates (often even being quenched), and less disky morphologies, than counterparts with late-forming haloes. The simulation show that early halo formation fosters the growth of more-massive central black holes (compared to late-forming haloes of similar present-day dynamical mass), and the extra feedback energy liberated by their growth depletes the circumgalactic medium of the efficiently cooling gas that would otherwise replenish interstellar gas consumed by star formation. A central prediction of this scenario is that the circumgalactic medium of quenched ~L* galaxies is of a lower density than that of star-forming counterparts, for which recent analyses of eROSITA X-ray data lend enticing support. I will also briefly show how controlled simulations, starting from “genetically modified” initial conditions, enable the influence of halo assembly history on galaxy evolution to be disentangled from large-scale environment effects.
Helen Walker
Title: Exploring atomic structure and dynamics in barocalorics for solid-state cooling
Conventional vapour-compression refrigeration relies on refrigerants that contribute both to global warming and ozone depletion. Barocaloric materials, in which a large isothermal entropy change is associated with a pressure-induced phase transition, offer an eco-friendly solid-state alternative. While an increasing number of materials are being identified as barocalorics, a microscopic understanding of what drives the entropy change is often lacking, negatively impacting the opportunity to create a roadmap for developing new optimised barocaloric materials. We have used a range of neutron scattering methods to investigate both the structure and dynamics in two barocaloric systems: ammonium sulfate and adamantane, obtaining an insight into the significance of configurational and dynamic entropy, providing ideas for crystal engineering better barocalorics for applications in both cooling and heat pumps.ing gas that would otherwise replenish interstellar gas consumed by star formation. A central prediction of this scenario is that the circumgalactic medium of quenched ~L* galaxies is of a lower density than that of star-forming counterparts, for which recent analyses of eROSITA X-ray data lend enticing support. I will also briefly show how controlled simulations, starting from “genetically modified” initial conditions, enable the influence of halo assembly history on galaxy evolution to be disentangled from large-scale environment effects.
Soko Matsumura
Title: The origins of the diversity of extrasolar planetary systems
Since the first discovery of an extrasolar planetary system thirty years ago, more than 5000 exoplanets in nearly 4000 exoplanetary systems have been detected. The diversity of orbital, physical, and chemical properties of these systems has been motivating and driving exoplanetary science for decades. On the other hand, the recent observations along with theoretical works have revolutionised our understanding of the birthplace of these planets – protoplanetary discs. In this talk, I will review recent planet formation models and discuss how the variety of planetary systems arises from different protoplanetary discs.
David Williams
Title: Radio transients in the run up to the SKA and ngVLA
Transient radio emission is associated with some of the most powerful and dynamic explosions in the Universe. By searching for transient radio emission associated with multi-wavelength transients like Gamma Ray Bursts, X-ray binaries, supernovae and flare stars, we can infer important source properties. Some of the more powerful radio transients reveal the presence of radio ejections which can be studied as they evolve into the ISM. New radio telescopes like the SKA and ngVLA will enable further study of radio transients but preparations must be made to extract the most information from these new powerful telescopes. In this talk, I will describe work using current telescopes like e-MERLIN, AMI and MeerKAT to explore the radio transient Universe using a variety of different observing techniques. I will highlight X-ray binaries as a specific science case to explore the potential for insights into black hole accretion and jet physics, focussing on two recent X-ray binaries, MAXI J1820+070 and EXO 1846-031. I will also describe the need for the continuation of current observatories long into the new era of high sensitivity radio observatories to follow up new discoveries from the SKA and ngVLA.
Thomas Rees-Crockford
Title: Pre-emergence Signatures of Horizontal Divergent Flows in Solar Active Regions
Solar active regions (ARs) play a fundamental role in driving many of the geoeffective eruptions, which propagate into the solar system. However, we are still unable to consistently predict where and when ARs will occur across the solar disk by identifying preemergence signatures in observables such as the Doppler velocity (without using helioseismic methods). Here we aim to determine the earliest time at which pre-emergence signatures, the horizontal divergent flow (HDF) in particular, can be confidently detected using data from the Solar Dynamics Observatory’s Helioseismic and Magnetic Imager. Initially, we follow previous studies using the thresholding method, which searches for significant increases in the number of pixels that display a specific line-of-sight velocity. We expand this method to more velocity windows and conduct a basic parameter study investigating the effect of cadence on the inferred results. Our findings agree with previous studies with 37.5% of ARs displaying an HDF, with average lead times between the HDF and flux emergence of 58 minutes. We present a new potential signature of flux emergence, which manifests as cadence-independent transient disruptions to the amplitudes of multiple velocity windows and recover potentialpreemergence signatures for 10 of the 16 ARs studied, with lead times of 60–156 minutes. Several effects can influence both the estimated times of both HDF and flux emergence suggesting that one may need to combine Doppler and magnetic field data to get a reliable indicator of continued flux emergence.
Daniel Verscharen
Title: Exploring cosmic plasma physics with Parker Solar Probe and Solar Orbiter
Parker Solar Probe and Solar Orbiter are the two latest flagship space missions in the field of heliophysics. Parker Solar Probe was launched in 2018. Its orbit brings the spacecraft and its four scientific instruments very close to the Sun, an astrophysical plasma environment that has not been explored with spacecraft before. Solar Orbiter was launched in 2020. Its comprehensive payload consists of ten scientific instruments which measure the plasma environment of the spacecraft in situ and observe the Sun remotely.
I will present results from both Parker Solar Probe and Solar Orbiter on a selection of these fundamental topics. I will use these examples to highlight the scientific capabilities of both missions and the potential for future studies of fundamental astrophysical plasma physics.