Too dense to go through: the role of low-mass clusters in the pre-processing of satellite galaxies

Abstract

We study the evolution of satellite galaxies in clusters of the C-EAGLE simulations, a suite of 30 high-resolution cosmological hydrodynamical zoom-in simulations based on the EAGLE code. We find that the majority of galaxies that are quenched at z = 0 (≳ 80${{\ \rm per\ cent}}$) reached this state in a dense environment (log10M200[M⊙] ≥13.5). At low redshift, regardless of the final cluster mass, galaxies appear to reach their quenching state in low mass clusters. Moreover, galaxies quenched inside the cluster that they reside in at z = 0 are the dominant population in low-mass clusters, while galaxies quenched in a different halo dominate in the most massive clusters. When looking at clusters at z > 0.5, their in-situ quenched population dominates at all cluster masses. This suggests that galaxies are quenched inside the first cluster they fall into. After galaxies cross the cluster’s r200 they rapidly become quenched (≲ 1Gyr). Just a small fraction of galaxies ($\lesssim 15{{\ \rm per\ cent}}$) is capable of retaining their gas for a longer period of time, but after 4Gyr, almost all galaxies are quenched. This phenomenon is related to ram pressure stripping and is produced when the density of the intracluster medium reaches a threshold of ρICM ∼ 3 × 10−5 nH (cm−3). These results suggest that galaxies start a rapid-quenching phase shortly after their first infall inside r200 and that, by the time they reach r500, most of them are already quenched.

The miniJPAS survey

“…If we assume that some of the blue galaxies belong to the original halo and some have been accreted later, we could explain the behaviour of blue galaxies and the greater dispersion of their properties, as well as the greater amount of quenching among inner ones. However, Pallero et al (2022) estimate that the quenching timescale for galaxies once the in-fall beyond R 200 is ∼ 1 Gyr, but our estimations of ∆t q are larger for blue galaxies, and only some of the red galaxies are compatible with these values, regardless of their distance to the cluster centre. These suggest that the accretion and evolution scenario may be more complex and a different model is required.…”

“…Maier et al 2019;Roberts et al 2019;Kipper et al 2021), whereby galaxies undergo slow quenching processes and, once they enter a dense environment, start a faster quenching phase. Results from Pallero et al (2022), using the C-EAGLE simulation support this scenario. They show that these processes usually become relevant at ∼ R 200 , where the ICM reaches a density high enough for ram-pressure stripping to become relevant.…”

“…Red galaxies may quenched within smaller structures that were later accreted to the cluster. According to the results from Pallero et al (2022) , for a cluster of this mass (M 200 = 3.3 × 10 14 M ), we would expect a similar fraction of galaxies quenched inside the cluster and quenched via pre-processing. However, we find that ∼ 73 % of the red galaxies are within R 200 , so in order to be compatible with these results, some of the inner red galaxies would have to be part of a different halo.…”

Evolución de las propiedades de galaxias en grupos y cúmulos

“…Los modelos de formación de galaxias han explorado la importancia relativa de diferentes mecanismos de supresión de la formación estelar, utilizando tanto simulaciones hidrodinámicas (e.g. Schaye et al, 2015;Bahé & McCarthy, 2015;Taylor et al, 2017;Davé et al, 2017;Pallero et al, 2019;Oman et al, 2021a;Donnari et al, 2021b,a;Pallero et al, 2022) como modelos semi-analíticos (e.g. De Lucia et al, 2012;Henriques et al, 2017;Stevens & Brown, 2017;Cora et al, 2018;Henriques et al, 2019).…”

“…La diferencia en el contenido de gas caliente al momento de caída entre las galaxias pasivas y activas a z = 0 podría indicar que los efectos de pre-procesado están actuando sobre galaxias ubicadas lejos del centro del cúmulo (McGee et al, 2009;Dressler et al, 2013;Pallero et al, 2022). Usualmente, el pre-procesado es cuantificado a partir de la fracción de galaxias pasivas al momento de caída a un cúmulo (Wetzel et al, 2012;Haines et al, 2015;Donnari et al, 2021a;Oman et al, 2021b).…”