Measuring the total infrared light from galaxy clusters at z = 0.5–1.6: connecting stellar populations to dusty star formation

Abstract

ABSTRACT Massive galaxy clusters undergo strong evolution from z ∼ 1.6 to z ∼ 0.5, with overdense environments at high-z characterized by abundant dust-obscured star formation and stellar mass growth which rapidly give way to widespread quenching. Data spanning the near- to far-infrared (IR) can directly trace this transformation; however, such studies have largely been limited to the massive galaxy end of cluster populations. In this work, we present ‘total light’ stacking techniques spanning $3.4\!-\!500\, \mu$m aimed at revealing the total cluster emission, including low-mass members and potential intracluster dust. We detail our procedures for WISE, Spitzer, and Herschel imaging, including corrections to recover the total stacked emission in the case of high fractions of detected galaxies. We apply our techniques to 232 well-studied log$\, M_{200}/\mathrm{M}_{\odot }\sim 13.8$ clusters in multiple redshift bins, recovering extended cluster emission at all wavelengths. We measure the averaged IR radial profiles and spectral energy distributions (SEDs), quantifying the total stellar and dust content. The near-IR profiles are well described by an NFW model with a high (c ∼ 7) concentration. Dust emission is similarly concentrated, albeit suppressed at $r\lesssim 0.3\,$Mpc. The measured SEDs lack warm dust, consistent with the colder SEDs of low-mass galaxies. We derive total stellar masses consistent with the theoretical Mhalo−M⋆ relation and specific star formation rates that evolve strongly with redshift, echoing that of log$\, M_{\star }/\mathrm{M}_{\odot }\gtrsim 10$ cluster galaxies. Separating out the massive population reveals the majority of cluster far-IR emission ($\sim 70\!-\!80{{\ \rm per\ cent}}$) is provided by the low-mass constituents, which differs from field galaxies. This effect may be a combination of mass-dependent quenching and excess dust in low-mass cluster galaxies.