Candidate Gravitationally Lensed Dusty Star-forming Galaxies in the Herschel Wide Area Surveys

TL;DR

This paper compiles a list of 77 candidate gravitationally lensed dusty star-forming galaxies from Herschel surveys, highlighting their potential for studying starburst phenomena in distant galaxies through follow-up observations.

Contribution

It introduces a new catalog of candidate lensed DSFGs from Herschel data, with spectroscopic redshifts and follow-up imaging confirming their lensing nature.

Findings

77 candidate lensed DSFGs identified

13 sources have spectroscopic redshifts > 1

Surface density of 0.21 per square degree

Abstract

We present a list of candidate gravitationally lensed dusty star-forming galaxies (DSFGs) from the HerMES Large Mode Survey (HeLMS) and the Herschel Stripe 82 Survey (HerS). Together, these partially overlapping surveys cover 372 deg$^{2}$ on the sky. After removing local spiral galaxies and known radio-loud blazars, our candidate list of lensed DSFGs is composed of 77 sources with 500 $\mu$m flux densities ($S_{500}$) greater than 100 mJy. Such sources are dusty starburst galaxies similar to the first bright Sub Millimeter Galaxies (SMGs) discovered with SCUBA. We expect a large fraction of this list to be strongly lensed, with a small fraction made up of bright SMG-SMG mergers that appear as Hyper-Luminous Infrared Galaxies (HyLIRGs; $\rm L_{IR}>10^{13} L_{\odot}$). Thirteen of the 77 candidates have spectroscopic redshifts from CO spectroscopy with ground-based interferometers, putting them at $z>1$ and well above the redshift of the foreground lensing galaxies. The surface density of our sample is 0.21 $\pm$ 0.03 deg$^{-2}$. We present follow-up imaging of a few of the candidates confirming their lensing nature. The sample presented here is an ideal tool for higher resolution imaging and spectroscopic observations to understand detailed properties of starburst phenomena in distant galaxies.