MULTI-WAVELENGTH LENS RECONSTRUCTION OF A PLANCK AND HERSCHEL-DETECTED STAR-BURSTING GALAXY

Abstract

We present a source-plane reconstruction of a Herschel and Planck -detected gravitationally lensed dusty star-forming galaxy (DSFG) at z  = 1.68 using Hubble , Submillimeter Array (SMA), and Keck observations. The background submillimeter galaxy (SMG) is strongly lensed by a foreground galaxy cluster at z  = 0.997 and appears as an arc with a length of ∼15″ in the optical images. The continuum dust emission, as seen by SMA, is limited to a single knot within this arc. We present a lens model with source-plane reconstructions at several wavelengths to show the difference in magnification between the stars and dust, and highlight the importance of multi-wavelength lens models for studies involving lensed DSFGs. We estimate the physical properties of the galaxy by fitting the flux densities to model spectral energy distributions leading to a magnification-corrected star-formation rate (SFR) of 390 ± 60 M yr −1 and a stellar mass of . These values are consistent with high-redshift massive galaxies that have formed most of their stars already. The estimated gas-to-baryon fraction, molecular gas surface density, and SFR surface density have values of 0.43 ± 0.13, 350 ± 200 pc −2 , and M yr −1 kpc −2 , respectively. The ratio of SFR surface density to molecular gas surface density puts this among the most star-forming systems, similar to other measured SMGs and local ULIRGs.