Galaxy Cluster Science in the Euclid Era

Representative image for thesis Tutors: Stefano Andreon, Marco Landoni, Alberto Moretti e Ginevra Trinchieri
Lasting: 3 years. PhD thesis.

The Euclid mission will revolutionise cosmology and cluster studies by making the most accurate measurements of Dark Matter and Dark Energy, and giving access to the holy grail of astrophysics, mass, for a very large population of galaxy clusters.
In particular, the excellent point spread function of the Euclid telescope will allow us to detect the weak deformations (shear) of background galaxies induced by the potential well of intervening galaxy clusters for over 35 thousand clusters (Andreon & Berge 2012).
This offer a direct measure of mass and a selection by total mass in place of using indirect tracers (e.g. galaxies and the intracluster medium) offering a view of the cluster population free of the biases that affect samples selected with those indirect tracers (e.g. Pacaud et al. 2007, Andreon et al. 2016, Orlowski-Scherer et al. 2021).
The thesis aims at studying the intracluster medium properties of the population of shear-selected clusters.
By a hierarchical joint X-ray/shear analysis, the thesis aims at addressing both the properties of the intracluster medium of each individual object (e.g. radial profiles of temperature, pressure, and mass) and of the population as a whole (e.g. the spread across the clusters).
It addresses the amplitude of the bias of current cluster samples selected with indirect tracers and is a pathfinder for the incoming Euclid mission (Laureijs et al. 2011) and later surveys having shear as primary science case: LSST-Rubin and Roman (Ivezic et al. 2019; Spergel et al. 2015).
The student will join the international Euclid Consortium and participate in its activities.
The starting sample and shear measurements that will be used in the thesis are from Subaru Hyper SuprimeCam SSP Survey (Aihara et al. 2018), which is the current weak-lensing survey more similar to Euclid.
Intracluster medium properties will be measured on XMM and eROSITA data for about 80 clusters.
Analysis methods availables for individual X-ray/shear studies (Andreon et al. 2022) will be applied to populations and made scalable by big data methods developed by Castagna et al. (2022).

References: Aihara et al., 2018, PASJ 70, 4 - Andreon & Berge, 2012, A&A 547, 117 - Andreon, Serra, Moretti, Trinchieri, 2016, A&A 585, A147 - Castagna, Andreon, Trombetta, Landoni, 2022, EPJ Web of Conferences, Volume 257, 9 - Andreon, Radovich, et al. 2022, in prep - Curazov, et al. 2021, A&A 651, A41 - Laureijs et al. 2011, Euclid Definition Study Report, arxiv:1110.3193 - Ivezic et al. 2019, ApJ 874, 111 - Orlowski-Scherer et al., 2021, A&A, 653, A135 - Pacaud et al. (Andreon), 2016, A&A, 592, A2 - Spergel, et al. 2015, WFIRST-AFTA 2015 Report, arxiv:1503.03757

Image: eROSITA view of the intracluster medium of the Coma Cluster [from Churazov et al. 2021].