The diversity of galactic stellar halos
Title: |
The diversity of galactic stellar halos |
DNr: |
SNIC 2020/14-59 |
Project Type: |
SNIC Small Storage |
Principal Investigator: |
Martin Rey <martin.rey@physics.ox.ac.uk> |
Affiliation: |
Lunds universitet |
Duration: |
2020-08-19 – 2021-02-01 |
Classification: |
10305 |
Keywords: |
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Abstract
The diffuse halo of stars surrounding galaxies provides a unique window on their formation and evolution in our Universe. The stellar halo is a tracer of a galaxy’s past assembly, originating from the accretion and stripping of stars previously formed in smaller objects.
However, such mergers and accretion events are stochastic for each galaxy: they are seeded by random early-universe perturbations inflated to cosmological scales. This stochasticity then couples with the complex non-linear physics of galaxy formation, generating large diversity in stellar halo properties. Advances in low-surface-brightness imaging have now enabled systematic surveys of extragalactic stellar halos, revealing the extent of this diversity.
In this project, we will use a new computational approach to causally connect the variety of observed stellar halo properties to different merger scenarios. The key novelty of our approach lies in our ability to re-simulate these five reference simulations using the “genetic modification” technique. This framework enables us to modify a specific aspect of a galaxy’s history, while reproducing all other untargeted features. Comparing reference merger scenarios with their related, modified counterparts then creates controlled experiments in a fully cosmological context. The end product of the project will be a simulation library cleanly testing the mapping between a galaxy’s merger history and the building of its stellar halo.