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PhD Projects: Extragalactic Astrophysics

* Drinking evolved stars and binaries from the Gaia firehose

In 2022, the ongoing Gaia mission released its first full data release that includes not only a deeper 3D motion picture for a significant fraction of the Milky Way, but also catalogs overflowing with binary and variable stars.  It is not an exaggeration to say that a virtual fountain of discoveries awaits any research student interested in binary stars and stellar evolution.  At UCL, students have recently led a number of scientific breakthroughs using Gaia; for example, a new phase of stellar evolution in which white dwarfs develop active chromospheres like our Sun, and a previously unknown population of ancient stars through unexpected carbon signatures in high velocity red dwarfs.  The data-driven and observational project will focus on improving our understanding of white dwarfs and dwarf carbon stars, variability, magnetism, binary fractions, origins and evolution.  Many major discoveries are just over the horizon thanks to Gaia.

Contact: Prof Jay Farihi (jfarihi AT star.ucl.ac.uk)

 

Gas in galaxies as a crucial link between theory and observation

Gas plays a crucial role in the lives of galaxies. It is the raw fuel for new star formation, but it is also heated and sometimes expelled from galaxies by the massive stars that it has just brought to life. Increasingly powerful observations allow us to trace gas in and around galaxies, piecing together clues to their history in a way that is highly complementary to observing the stellar populations alone. This project will explore new ways to constrain the physics of galaxy formation by using our growing understanding of gas in the Universe.  It is a rare opportunity to work with both simulations and observations. Depending on your preference, there is an opportunity to work either primarily with simulations from the GMGalaxies team (led by Andrew Pontzen), or to work primarily with an observational team (led by Amelie Saintonge). Either way, you will interact with both groups.

Contact: Prof Amelie Saintonge (a.saintonge AT ucl.ac.uk) and Prof Andrew Pontzen  (a.pontzen AT ucl.ac.uk)

 

The many scales of star formation: from halos to molecular clouds

Our view of the connection between the large scale properties of galaxies, their environments, interstellar medium, and the physics of star formation is currently being reshaped. New observations are revealing that star formation is a multi-scale process, pointing to a deep connection between the location of galaxies in the cosmic web, their ability to refuel their gas reservoirs, and ultimately turning this gas into stars. In this project, you will explore the connection between galaxies (in particular their cold gas contents and star formation activity) and the large scale environment they occupy (dark matter halo masses and location in the cosmic web) to lend further evidence for this multi-scale connection. You will become a member of the DESI and 4MOST-WAVES surveys, making use of these data to quantify the environments of galaxies, with the possibility to get involved with infrastructure and observing work for these large projects. There is also an oportunity to work with ALMA/IRAM/JCMT data, and to collaborate with other members of the UCL Extragalactic group on related topics. 

Contact: Prof Amelie Saintonge (a.saintonge AT ucl.ac.uk)

 

Exploring the relationship between the early Universe and today’s galaxies

We know that the observable properties of galaxies – their colours and shapes, for example – depend sensitively on their histories, which in turn are determined by inflationary density perturbations in the very early Universe.  There is an opportunity to join the GMGalaxies team (https://gmgalaxies.org) to examine these fundamental links using a unique set of numerical tools. We pioneered “genetic modification” – which involves generating multiple, slightly different sets of early-Universe conditions from which a given galaxy will emerge. As each version of the Universe is evolved in its own computer simulation, the initial differences lead to contrasting evolutions; for instance, the galaxy might be formed earlier or later in the Universe's history, or undergo a different number of mergers with other galaxies. We study these variations and how they impact on the observed galaxy population. There are a broad range of available projects within this programme. There are opportunities to make comparisons to observations, to perform dynamical analyses of simulated galaxies, or to further develop our techniques using statistical and physical models of the very early Universe. 

Contact: Prof Andrew Pontzen  (a.pontzen AT ucl.ac.uk)

 

Related projects are also advertised under Cosmology & Surveys