Student : SANTIAGO Iris
Advisors : POINTECOUTEAU Etienne, CARETTA Cesar A. (University of Guanajuato, Mexique) et BRAVO-ALFARO Hector (University of Guanajuato, Mexique)
Start : Octobre 2015
Group : GAHEC
According to the current cosmological models, most of the baryonic material in the Universe has not yet been observed. Numerical simulations suggest that from one-half to two-thirds of all baryons may be located between clusters of galaxies, forming the Large Scale Structure (LSS). The LSS baryonic component is composed by substructures of gas and galaxies
(groups, clusters, elongated filaments and widely spread sheets) tracing the underlying distribution of dark matter. The most massive halos (i.e., groups and clusters) contain high density hot gas (kT ∼ 1−10 keV, T ∼ 10^7 − 10^8 K) which radiatively cools and emits at X-rays wavelengths and interacts with the cosmic microwave background at millimeter wavelengths through the Sunyaev−Zel’dovich (SZ) effect. For the less dense sub-structures, filaments and sheets, the baryons are probably in moderately hot gas phase (0.01−1 keV), commonly named as warm hot intergalactic medium (WHIM). For this PhD project, we propose to study the environmental effects associated to the different components of the LSS. For the less dense components, we assembled a sample of filament candidates composed by chains of clusters and groups that are located inside superclusters of galaxies. We aim to probe the filament structure and characterize their various components (galaxies, groups/clusters halos, gas). For the higher density components, the galaxy clusters, we aim to characterize the intra cluster medium (ICM) using the SZ effect. We exploit the ACT and Planck data to analyze the gas of a sample of low mass galaxy clusters.