GLACE survey: galaxy activity in ZwCl0024+1652 cluster from strong optical emission lines

Abstract

Although ZwCl0024+1652 galaxy cluster at 𝑧 ∼ 0.4 has been thoroughly analysed, it lacks a comprehensive study of star formation and nuclear activity of its members. With GaLAxy Cluster Evolution (GLACE) survey, a total of 174 H𝛼 emission-line galaxies (ELGs) were detected, most of them having [N ]. We reduced and analysed a set of [O ] and H𝛽 tunable filter (TF) observations within GLACE survey. Using H𝛼 priors, we identified [O ] and H𝛽 in 35 (∼20%) and 59 (∼34%) sources, respectively, with 21 of them having both emission lines, and 20 having in addition [N ]. Applying BPT-NII diagnostic diagram, we classified these ELGs into 40% star-forming (SF), 55% composites, and 5% LINERs. Star formation rate (SFR) measured through extinction corrected H𝛼 fluxes increases with stellar mass (M * ), attaining its peak at M * ∼ 10 9.8 M . We observed that the cluster centre to ∼ 1.3 Mpc is devoid of SF galaxies and AGN. Our results suggest that the star formation efficiency declines as the local density increases in the cluster medium. Moreover, the SF and AGN fractions drop sharply towards high-density environments. We observed a strong decline in SF fraction in high M * , confirming that star formation is highly suppressed in high-mass cluster galaxies. Finally, we determined that SFR correlates with M * while specific SFR (sSFR) anti-correlates with M * , both for cluster and field. This work shows the importance and strength of TF observations when studying ELGs in clusters at higher redshifts. We provide with this paper a catalogue of ELGs with H𝛽 and/or [O ] lines in ZwCl0024+1652 cluster.