The stellar mass function of galaxies in Planck-selected clusters at 0.5 < z < 0.7: new constraints on the timescale and location of satellite quenching

Abstract

We study the abundance of star-forming and quiescent galaxies in a sample of 21 clusters at 0.5 < z < 0.7, detected with the Planck satellite. Thanks to the large volume probed by Planck, these systems are extremely massive, and provide an excellent laboratory to study any environmental effects on their galaxies' properties. We measure the cluster galaxy stellar mass function (SMF), which is a fundamental observable to study and constrain the formation and evolution of galaxies. Our measurements are based on homogeneous and deep multi-band photometry spanning u-to the K s -band for each cluster and are supported by spectroscopic data from different programs. The galaxy population is separated between quiescent and star-forming galaxies based on their rest-frame U-V and V-J colours. The SMF is compared to that of field galaxies at the same redshifts, using data from the COSMOS/UltraVISTA survey. We find that the shape of the SMF of star-forming galaxies does not depend on environment, while the SMF of quiescent galaxies has a significantly steeper low-mass slope in the clusters compared to the field. This indicates that a different quenching mechanism is at play in clusters compared to the field, accentuated by a quenched fraction that is much higher in the clusters. We estimate the environmental quenching efficiency ( f EQ ), i.e. the probability for a galaxy that would normally be star forming in the field, to be quenched due to its environment. The f EQ shows no stellar-mass dependence in any environment, but it increases from 40% in the cluster outskirts to ∼ 90% in the cluster centres. The radial signature of f EQ provides constraints on where the dominant quenching mechanism operates in these clusters and on what timescale. Exploring these using a simple model based on galaxy orbits obtained from an N-body simulation, we find a clear degeneracy between both parameters. For example, the quenching process may either be triggered on a long (∼3 Gyr) time scale at large radii (r ∼ 8R 500 ), or happen well within 1 Gyr at r < R 500 . The radius where quenching is triggered is at least r quench > 0.67R 500 (95%CL). The ICM density at this location (as probed with XMM-Newton), suggests that ram-pressure stripping of the cold gas is a likely cause of quenching. In addition to this cluster-quenching mechanism we find that 20-32%, depending on the cluster-specific quenching process, of accreted galaxies were already pre-processed (i.e. quenched by the surrounding overdensities) before they fell into the clusters.

The GOGREEN survey: dependence of galaxy properties on halo mass at z &gt; 1 and implications for environmental quenching

“…This has been thoroughly demonstrated in works studying dense environments of rich groups and clusters in the local z ∼ 0 Universe (Gómez et al 2003;Balogh et al 2004a;Kauffmann et al 2004;Hou, Parker & Harris 2014), as well as intermediate 0 < z < 1 redshifts (De Lucia et al 2004;Wilman et al 2005;Cooper et al 2006;McGee et al 2011;Giodini et al 2012;van der Burg et al 2018;Just et al 2019) and at z > 1 (Muzzin et al 2012;Balogh et al 2014;Nantais et al 2016;Guglielmo et al 2019;Strazzullo et al 2019;van der Burg et al 2020). At low redshifts, the dependence of the quiescent fraction on stellar mass and environment is largely separable (Baldry et al 2006;Peng et al 2010;Kovač et al 2014;Balogh et al 2016;van der Burg et al 2018). This has been interpreted to indicate that the dominant physical mechanisms are also separable (e.g.…”

“…The fraction of quiescent galaxies increases strongly with stellar mass, for M stellar > 10 9 M (e.g. Kauffmann et al 2003Kauffmann et al , 2004Brinchmann et al 2004;Baldry et al 2006;Weinmann et al 2006;Kimm et al 2009;Muzzin et al 2012;van der Burg et al 2018). At fixed stellar mass, the quiescent fraction declines with increasing redshift, and is higher in denser environments.…”

“…Comparison of data with models is challenging, however, in part because there are many different, commonly used definitions of environment. These include local density (Cooper et al 2006;Peng et al 2010;Sobral et al 2011;Darvish et al 2016;Davidzon et al 2016;Kawinwanichakij et al 2017;Papovich et al 2018;Lemaux et al 2019), group/cluster virial masses, and cluster-centric distance (Poggianti et al 2006;Oman, Hudson & Behroozi 2013;Muzzin et al 2014;Paccagnella et al 2016;van der Burg et al 2018van der Burg et al , 2020, and status as central or satellite in halo (Muzzin et al 2012;Mok et al 2013;Balogh et al 2016). The quiescent fraction at fixed stellar mass correlates with environment in most cases, but the interpretation of the physical mechanisms behind the observed trends remains elusive, in part because of the difficulty linking these observations to theoretical models.…”

The Roles of Mass and Environment in the Quenching of Galaxies. II.

“…The excess of galaxies that are quenched with respect to the field, and in our case the excess of satellites (cluster environment) with respect to centrals (field) is calculated at the same epoch. As many authors noted (e.g., Balogh et al 2016;van der Burg et al 2018), a better approach would be to consider the quenched fraction in the field at the time of accretion. Theoretically speaking, this would be possible with models of galaxy formation that are able to trace the history of any single galaxy, such as ours, but observationally impossible without assumptions (which anyway would not avoid the progenitor bias issue) on the different galaxy populations.…”

“…Quadri et al (2012), who used a massselected sample from UKIDSS Ultra-Deep Survey, echo Peng et al's results for what concerns env and extend them to higher redshifts. More recently, van der Burg et al (2018), who study a sample of 21 clusters at z ∼ 0.6 (on average) detected by Planck, find that the environmental quenching efficiency is stellar mass independent in any environment, although it increases toward the inner regions of the clusters.…”