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Anna Patej (Harvard) "Distributions of Baryons from the Virial Radius of Galaxy Clusters to Large Scales"
November 17, 2015 @ 4:00 pm - 5:00 pm
Abstract:
I will discuss my recent work on the distributions of baryonic matter on various scales, from the gas and galaxies in galaxy clusters to the clustering of massive galaxies on large scales. Near the virial radius of galaxy clusters, long-standing analytical models of structure formation as well as recent simulations predict the existence of steep density jumps in the gas and dark matter profiles. I will describe a new method for deriving models for the gas distribution in galaxy clusters, which relies on a few basic assumptions — including the existence of such density jumps — and show a resulting profile for the gas that is in good agreement with X-ray observations of cluster interiors and simulations of the outskirts.
Since cluster member galaxies are expected to follow similar collisionless dynamics as the dark matter, the galaxy density profile should show a steep density jump as well. I will address the question of whether we can find evidence for a feature consistent with a density jump with current observations, and will additionally discuss avenues for probing the density jumps with future data sets.
Moving to larger scales where massive galaxies of different types are expected to roughly trace the same large-scale structure, I will present a test of this prediction by measuring the clustering of red and blue galaxies at z~0.6 using the CMASS sample of galaxies from DR12 of SDSS-III. The stochasticity between these two samples can be quantified via the correlation coefficient r, which can be constructed from two different statistics, both of which indicate that on intermediate scales (20 < R < 100 Mpc/h) there is low stochasticity between the two samples of galaxies.
Lastly, I will describe some ongoing and future observational efforts, focusing on my involvement with the DECam Legacy Survey (DECaLS), a pathfinder imaging survey for the upcoming Dark Energy Spectroscopic Instrument (DESI) galaxy redshift survey.
Slides