A Submillimeter Survey of Faint Galaxies Behind Ten Strong Lensing Clusters

TL;DR

This study uses deep submillimeter imaging and ALMA observations of ten strong lensing clusters to catalog faint galaxies, analyze their redshift distribution, and identify high-redshift candidates, revealing insights into galaxy evolution and extinction.

Contribution

It provides the first comprehensive catalog of faint submillimeter galaxies behind lensing clusters, combining SCUBA-2, ALMA, and spectroscopic data to study their properties and redshift distribution.

Findings

No evolution in redshift distribution down to 0.5 mJy fluxes.

Fainter submillimeter galaxies have less extinction.

Identified 55 z>4 bright candidates.

Abstract

We present deep SCUBA-2 450 micron and 850 micron imaging of ten strong lensing clusters. We provide a >4-sigma SCUBA-2 850 micron catalog of the 404 sources lying within a radius of 4.5' from the cluster centers. We also provide catalogs of the >4.5-sigma ALMA 870 micron detections in the clusters A370, MACSJ1149.5+2223, and MACSJ0717.5+3745 from our targeted ALMA observations, along with catalogs of all other >4.5-sigma ALMA (mostly 1.2 mm) detections in any of our cluster fields from archival ALMA observations. For the ALMA detections, we give spectroscopic or photometric redshifts, where available, from our own Keck observations or from the literature. We confirm the use of the 450 micron to 850 micron flux ratio for estimating redshifts. We use lens models to determine magnifications, most of which are in the 1.5-4 range. After supplementing the ALMA cluster sample with Chandra Deep Field (CDF) ALMA and SMA samples, we find no evidence for evolution in the redshift distribution of submillimeter galaxies down to demagnified 850 micron fluxes of 0.5 mJy. Given this result, we conclude that our observed trend of increasing F160W to 850 micron flux ratio from brighter to fainter demagnified 850 micron flux results from the fainter submillimeter galaxies having less extinction. However, there is wide spread in this relation, including the presence of some optical/NIR dark galaxies down to fluxes below 1 mJy. Finally, with insights from our ALMA analysis, we analyze our SCUBA-2 sample and present 55 850 micron-bright z>4 candidates.