Tracing the quenching history of cluster galaxies in the EAGLE simulation

PALLERO, DIEGO; GÓMEZ, FACUNDO A; PADILLA, NELSON D; TORRES-FLORES, S; DEMARCO, R; CERULO, P; OLAVE-ROJAS, D

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 vol. 488 p. 847 - 858

0035-8711

We use the Evolution and Assembly of GaLaxies and their Environments (EAGLE) hydrodynamical simulation to trace the quenching history of galaxies in its 10 most massive clusters. We use two criteria to identify moments when galaxies suffer significant changes in their star formation activity: (i) the instantaneous star formation rate (SFR) strongest drop, Γ _SFR^SD, and (ii) a `quenching' criterion based on a minimum threshold for the specific SFR of ≲10^{-11} yr^{-1}. We find that a large fraction of galaxies ({≳} 60 per cent) suffer their Γ _SFR^SD outside the cluster's R200. This `pre-processed' population is dominated by galaxies that are either low mass and centrals or inhabit low-mass hosts (1010.5 ≲ Mhost ≲ 1011.0 M☉). The host mass distribution is bimodal, and galaxies that suffered their Γ _SFR^SD in massive hosts (10^{13.5} ≲ M_host ≲ 10^{14.0} M_{☉}) are mainly processed within the clusters. Pre-processing mainly limits the total stellar mass with which galaxies arrive in the clusters. Regarding quenching, galaxies preferentially reach this state in high-mass haloes (10^{13.5} ≲ M_host ≲ 10^{14.5} M_{☉}). The small fraction of galaxies that reach the cluster already quenched have also been pre-processed, linking both criteria as different stages in the quenching process of those galaxies. For the z = 0 satellite populations, we find a sharp rise in the fraction of quenched satellites at the time of first infall, highlighting the role played by the dense cluster environment. Interestingly, the fraction of pre-quenched galaxies rise with final cluster mass. This is a direct consequence of the hierarchical cosmological model used in these simulations.