12:00–1:00 pm ERC 501
Host: Jeff McMahon
Hayley Macpherson "The distance-redshift relation beyond FLRW"
The distance-redshift relation beyond FLRW Abstract: Most of cosmology today relies on the existence of a spatially homogeneous and isotropic space-time metric to predict, simulate, and constrain cosmological dynamics. This is the Friedmann-Lemaitre-Robertson-Walker (FLRW) class of models, and when applied within general relativity they form the backbone of the standard LCDM model. We are beginning to see potential cracks in LCDM as our data becomes more precise, and, of course, ~ 95% of the Universe remains physically unexplained within this model. Questioning and investigating the simplifying assumptions adopted in LCDM is thus important before we accept new physics as a potential explanation for any of these issues. I will provide a base-level introduction to what the FLRW model assumptions imply physically and how they enter various aspects of cosmology. I will then introduce the low redshift luminosity distance-redshift relation and compare its form within the context of FLRW to that for a generic metric tensor. From this example, I will show how our physical interpretation of well-known cosmological parameters can change when we drop the FLRW assumption and consider the inhomogeneity of space-time.
Floor van Donkelaar "The formation scenarios for the Milky Way’s nuclear star cluster"
Nuclear star clusters (NSCs) are massive star clusters found in the innermost region of the majority of galaxies. The formation channel of the Milky Way’s NSC is still uncertain. In this talk, I’ll describe a formation scenario found by GigaEris, a high resolution N-body hydrodynamical cosmological “zoom-in” simulation, and its connection to the other structures in the Milky Way.
