Two PhD Positions in Extragalactic Astrophysics

We invite applications for two PhD positions in extragalactic astrophysics at the Centre de Recherche Astrophysique de Lyon (Université Claude Bernard Lyon 1, UCBL) within the ANR-funded Research Group led by Dr. Jens-Kristian Krogager.

The group studies the evolution of the molecular gas reservoir in galaxies at redshifts around 2 to 3 (so-called cosmic noon) using quasar absorption line systems. Our group also focuses on understanding the chemical properties of the neutral gas, such as metallicity and dust content; and furthermore how these absorption-derived properties relate to the galaxies that we observe in emission.

The project will primarily exploit data from the upcoming 4MOST spectrograph at the ESO/VISTA telescope in Chile. 4MOST is a multi-object fibre-feb spectrograph observing 2436 fibres simultaneously over a roughly 4 square degree field of view. Our group is leading the 4MOST-Gaia Purely Astrometric Quasar Survey (4G-PAQS) which will observe around 300,000 quasar candidates selected from Gaia astrometry alone. We will also exploit radio data from MeerKAT and follow-up observations from the VLT.

The two PhD projects will focus on 1) the analysis of the absorption systems identified in the spectroscopic data of 4MOST and 2) the analysis of the numerical simulations in order to assist the interpretation of the data. The observational component involves identifying absorption systems across redshifts and characterizing their chemical and kinematic properties in collaboration with leading experts (P. Noterdaeme, S. Balashev, A. De Cia). The theoretical component includes analyzing cutting-edge simulations (e.g., FIREbox, Sphinx, NewHorizon) to study molecular gas properties and their evolution over time while investigating the effects of numerical methods and AGN feedback. The numerical project will be carried out in collaboration with experts and developers of these simulations (J. Blaizot, J. Rosdahl, Y. Dubois).

The earliest starting date for the positions is April 1st 2025 for a fixed term of 3 years. The starting date is negotiable.

Applicants should hold a Master’s degree in Physics, Astronomy/Astrophysics, or equivalent at the time of starting the PhD. The position requires high-level English proficiency in both written and spoken communication. As the group leader is based in Santiago, Chile until mid 2026 the candidates should be independent and comfortable working with virtual meetings and supervision. Regular visits between Chile and France are foreseen.

Knowledge in extragalactic astrophysics and proficiency in coding (e.g., with python) is desirable. Demonstrated experience in astronophysical numerical simulations is an additional asset.

For more information about the projects, please contact Dr. Jens-Kristian Krogager ([email protected])