A homogeneous measurement of the delay between the onsets of gas stripping and star formation quenching in satellite galaxies of groups and clusters

Abstract

We combine orbital information from N-body simulations with an analytic model for star formation quenching and SDSS observations of galaxy positions, redshifts, and colours to infer the differential effect of the group/cluster environment on star formation in satellite galaxies. We repeat a similar exercise with a similar model for gas stripping and supplement the same input catalogue with H I fluxes from the ALFALFA survey. The statistical models are motivated by and tested on the Hydrangea cosmological hydrodynamical simulation suite. Our models recover the typical time when galaxies in the satellite population are stripped and quenched: stripping in massive (M vir ∼ 10 14.5 M ) clusters typically occurs at or just before the first pericentric passage, and up to ∼ 4 Gyr later in low mass (∼ 10 12.5 M ) groups. Quenching occurs later: Balmer emission lines typically fade ∼ 4 Gyr (6.5 Gyr) after first pericentre in clusters (groups), followed a few hundred Myr later by reddenning in (g − r) colour. These 'delay timescales' are remarkably constant across the entire satellite stellar mass range probed (∼ 10 9.5 -10 11 M ); this feature is closely tied to our treatment of 'group pre-processing'. While our measurements are qualitatively consistent with the 'delayedthen-rapid' quenching scenario advocated for by several other studies, we find significantly longer delay times. The origin of this apparent discrepancy is difficult to pinpoint. However, our unique use of a homogeneous analysis and input catalogues yields new insight into the sequence of events leading to quenching across wide intervals in host and satellite mass.

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

“…Is important to note however that, even though both Rhee et al (2020) and Oman et al (2020) consider preprocessing as an important aspect in galaxy evolution, they cannot directly account for the pre-processing effects as we do in our work. Given the nature of combining data from observations and orbits from simulations, in their work it is not possible to measure if the observed satellites inhabited other massive halo prior to their accretion into their final cluster.…”

“…Furthermore, for this particular result, we are not taking into account the time spent within the host in which they eventually get quenched. Nonetheless, as we see in Figure 4, galaxies get quenched shortly after their first accretion event (but see Oman et al 2020, for observational evidence to the contrary).…”

“…By combining the star formation histories of observed galaxies with the evolutionary tracks of simulated galaxies, some studies have tried to constrain the accretion history of individual cluster galaxies to better understand their quenching process. Based on satellite orbital model extracted from the hydrangea and the YZiCS simulations Oman et al (2020) and Rhee et al (2020), respectively, were able to characterize the different stages of the quenching process proposed by Wetzel et al (2013); i.e. the "delayed-then-rapid" quenching model.…”

“…In particular, Rhee et al (2020) found that the total timescale for quenching to take place is around ∼ 5 Gyr. In the other hand, Oman et al (2020) finds that the quenching timescales for satellites in clusters could be as…”

“…Given the nature of combining data from observations and orbits from simulations, in their work it is not possible to measure if the observed satellites inhabited other massive halo prior to their accretion into their final cluster. Furthermore, both Rhee et al (2020) and Oman et al (2020) measure the quenching timescale as the moment when galaxies start to decrease their star formation rate, up to the moment when their star formation rate is completely depleted. Instead, in our work we consider the timescale between the moment when galaxies crosses the virial radii of a cluster for the first time, an their last star formation rate event.…”