Spitzer Imaging of Herschel-ATLAS Gravitationally Lensed Submillimeter Sources

TL;DR

This paper analyzes two gravitationally lensed submillimeter galaxies from the Herschel survey using Spitzer imaging, revealing their high dust obscuration, star formation rates, and low gas fractions compared to similar galaxies.

Contribution

It provides detailed spectral energy distribution constraints for these lensed SMGs, enhancing understanding of their physical properties and lensing effects.

Findings

High dust obscuration with Av ~4-5

Star formation rates around 100 M_sun/yr

Lower gas fractions and dynamical masses

Abstract

We present physical properties of two submillimeter selected gravitationally lensed sources, identified in the Herschel Astrophysical Terahertz Large Area Survey. These submillimeter galaxies (SMGs) have flux densities > 100 mJy at 500 um, but are not visible in existing optical imaging. We fit light profiles to each component of the lensing systems in Spitzer IRAC 3.6 and 4.5 um data and successfully disentangle the foreground lens from the background source in each case, providing important constraints on the spectral energy distributions (SEDs) of the background SMG at rest-frame optical-near-infrared wavelengths. The SED fits show that these two SMGs have high dust obscuration with Av ~4 to 5 and star formation rates of ~100 M_sun/yr. They have low gas fractions and low dynamical masses compared to 850 um selected galaxies.