What are the underlying physical mechansism driving the ejection of matter at nearly the speed of light from the hearts of black holes? Researchers within the extragalactic astrophysics group are leading the charge to understand these mysterious objects.
The galaxy dynamics group at the Jeremiah Horrocks Institute studies the dynamics of galaxies, including the Milky Way, to understand their formation and evolution. Our main approach is using supercomputer simulations to model the formation and evolution of galaxies. Key questions we are interested in include the dynamics of bars and their interactions with bulges, discs and halos, the influence of clumps on the chemodynamical evolution of galaxies, and the effect of the outer disc on the overall behaviour of galaxies. The galaxy dynamics group makes use of Gaia data, and is part of the Vera Rubin Telescope bulge collaboration, the VVVX survey, WEAVE and Gaia-ESO. The group is part of the Composite Bulges Survey collaboration, which is using Hubble Space Telescope (HST) data for a complete census of the structures at the centres of galaxies. We are also fortunate enough to be using data from Season 1 of the James Webb Space Telescope (JWST) to understand galaxies at redshifts z ~ 3 and the much nearer Andromeda Galaxy. See more
Galaxy evolution and Stellar Populations
The ages and chemical compositions of different populations of stars in galaxies can tell us a great deal about the formation and evolution of galaxies and their various structural components. Spiral galaxies are complex systems with both actively star forming and passive components, including disks, bulges, halos, bars and spiral arms, whereas early-type galaxies [elliptical and lenticular galaxies] generally have lower levels of star formation and are dominated by a single structural component. However, exactly when, and sometimes where, their stars were made is hard to uncover. In most external galaxies we cannot resolve individual stars, but instead we observe the integrated light from various populations of stars. The stellar populations group works to make sense of the information provided by these jumbled stellar populations and to constrain the method of formation of the various galactic components. Stellar databases such as MILES are being developed to increase our understanding of stellar populations in galaxies. Anne Sansom leads the UK membership of the MILES international consortium.
Our collaborations studying large surveys of galaxies (such as the GAMA and H-ATLASconsortia, of which Anne Sansom and Cristina Popescu are members) allow us to probe the conditions of galaxies of different masses, environment, structure and inter-stellar medium properties. These surveys are revealing more diversity of galaxy morphologies and new methods allow us to study their histories.
Observational Cosmology and Quasars
Dr Roger Clowes leads an international team investigating quasars. More specifically the grouping of quasars together to form a large scale structure but also the enviroment surrounding these quasars and the quasar emission
Quasars are the nuclei of galaxies from the early years of the universe. Quasars undergo brief periods of extremely high brightness that make them visible across huge distances. These periods are ‘brief’ in astrophysics terms but actually last 10-100 million years.
One such structure discovered by Dr Clowes is the Huge-LQG. With a characteristic size (volume1/3) ∼ 500 Mpc (present epoch). Whole clusters of galaxies can be 2-3 Mpc across, but LQGs can be 200 Mpc or more across.
The Interstellar Medium Group led by Prof. Cristina Popescu investigates the formation and evolution of galaxies by studying the detailed physical processes that take place in these complex systems related to the interaction of radiation with dust, gas and cosmic rays