A large Hα survey of star formation in relaxed and merging galaxy cluster environments atz∼ 0.15–0.3

Abstract

We present the first results from the largest Hα survey of star formation and AGN activity in galaxy clusters. Using 9 different narrow band filters, we select > 3000 Hα emitters within 19 clusters and their larger scale environment over a total volume of 1.3 × 10 5 Mpc 3 . The sample includes both relaxed and merging clusters, covering the 0.15 − 0.31 redshift range and spanning from 5 × 10 14 M to 30 × 10 14 M . We find that the Hα luminosity function (LF) for merging clusters has a higher characteristic density φ * compared to relaxed clusters. φ * drops from cluster core to cluster outskirts for both merging and relaxed clusters, with the merging cluster values ∼ 0.3 dex higher at each projected radius. The characteristic luminosity L * drops over the 0.5 − 2.0 Mpc distance from the cluster centre for merging clusters and increases for relaxed objects. Among disturbed objects, clusters hosting large-scale shock waves (traced by radio relics) are overdense in Hα emitters compared to those with turbulence in their intra-cluster medium (traced by radio haloes). We speculate that the increase in star formation activity in disturbed, young, massive galaxy clusters can be triggered by interactions between gas-rich galaxies, shocks and/or the intra-cluster medium, as well as accretion of filaments and galaxy groups. Our results indicate that disturbed clusters represent vastly different environments for galaxy evolution compared to relaxed clusters or average field environments.

Emission Line Galaxies in the SHARDS Frontier Fields I: Candidate Selection and the Discovery of Bursty Hα Emitters

“…Their results indicate that cluster fields are overdense in H𝛼 emitters, with the luminosity function showing a strong dependence on the dynamic state of the cluster. Considering recent simulations suggesting A0370 is a merging system (Molnar et al 2020) along with the volume probed by the SHARDS data, our results are consistent with the work of Stroe et al (2017) finding similar number densities of H𝛼 emitters, considering our deeper depth. This also confirms our approach towards finding these emitters is sound and consistent with previous work.…”

“…This is consistent with our results if the overdensity in the A0370 cluster field can be attributed to the sources being cluster members. This is further supported by the work of Stroe et al (2017) in which 9 narrow band filters are used to select over 3000 H𝛼 emitters from 19 galaxy clusters and their large scale environments (beyond 2 Mpc from cluster centre). Their results indicate that cluster fields are overdense in H𝛼 emitters, with the luminosity function showing a strong dependence on the dynamic state of the cluster.…”

A 16 deg2 survey of emission-line galaxies at z < 1.5 in HSC-SSP Public Data Release 1

“…This structure including two galaxy clusters should be one of the interesting regions to investigate the environmental dependence of galaxy properties, which is discussed in another paper by Koyama et al (2017). HAEs in the merging clusters at z ∼ 0.15-0.3 are also investigated by Stroe et al (2017) (see also . Figure 12 shows that the O3Es at z ≈ 0.63 and 0.84 do not solely trace galaxy clusters.…”

“…Many surveys, targeting emission-line galaxies at z < ∼ 2, have been conducted so far (e.g., Bunker et al 1995;Thompson et al 1996;Moorwood et al 2000;van der Werf et al 2000;Fujita et al 2003;Doherty et al 2006;Shioya et al 2008;Villar et al 2008;Dale et al 2010;Ly et al 2007;Ly et al 2011;Bayliss et al 2011;Lee et al 2012;Best et al 2013;Colbert et al 2013;Ciardullo et al 2013;Drake et al 2013;Pirzkal et al 2013;Sobral et al 2013;Sobral et al 2015;An et al 2014;Khostovan et al 2015;Comparat et al 2015;Comparat et al 2016;Stroe & Sobral 2015;Stroe et al 2017). As a result, the cosmic SFR density has been established with a peak at z = 1-3 and then a gradually decline towards the local Universe (e.g., Hopkins & Beacom 2006;Madau & Dickinson 2014).…”

The nature of H α-selected galaxies along the large-scale structure at z = 0.4 revealed by Subaru Hyper Suprime-Cam survey

“…Shimasaku et al 2003;Kodama et al 2004;Hayashino et al 2004;Matsuda et al 2004;Ouchi et al 2005;Ideue et al 2009;Hayashi et al 2010;Koyama et al 2011;Sobral et al 2011;Matsuda et al 2011;Tadaki et al 2012;Yamada et al 2012;Toshikawa et al 2012;Kajisawa et al 2013;Darvish et al 2014;Shimakawa et al 2017;Stroe et al 2017). Unlike multi-object spectroscopy, NB imaging technique allows one to construct a complete sample of galaxies down to a certain level of emission line flux (hence SFR) over the observed field of view.…”