The Ages of Galaxy Clusters: A New (or Old?) Cosmological Test
James Taylor
University of Waterloo

The abundance of galaxy clusters provides an important cosmological test, constraining a product of the initial amplitude of fluctuations and the amount by which these fluctuations have grown since early times. The degeneracy of the test with respect to these two factors remains a major limitation of abundance studies. Clusters will have different mean assembly times, however, depending on the relative importance of initial fluctuation amplitude and subsequent growth. Thus, structural probes of cluster age such as concentration, shape, or substructure could produce a ?new? cosmological test that breaks the main degeneracy in cluster number counts, as first suggested (and attempted!) almost three decades ago. I'll discuss our recent work on the potential sensitivity of structural tests in forthcoming surveys such as Euclid, Roman, eROSITA, or CMB-S4. We are also starting to build up a more detailed, complex theoretical picture of how CDM halo structure evolves with time, which should lead to evolutionary tracks for galaxy clusters similar to those we draw on the HR diagram.

Date:	Jeudi, 17 mars 2022
Time:	11:30
Where:	Université de Montréal
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