HerMES: THE REST-FRAME UV EMISSION AND A LENSING MODEL FOR THE z=6.34 LUMINOUS DUSTY STARBURST GALAXY HFLS3

We discuss the rest-frame ultraviolet emission from the starbursting galaxy HFLS3 at a redshift of 6.34. The galaxy was discovered in Herschel/SPIRE data due to its red color in the submillimeter wavelengths from 250 to 500 m. Keck/NIRC2 K-s-band adaptive optics imaging data showed two potential near-IR counterparts near HFLS3. Previously, the northern galaxy was taken to be in the foreground at z = 2.1, while the southern galaxy was assumed to be HFLS3' s near-IR counterpart. The recently acquired Hubble/WFC3 and Advanced Camera for Surveys (ACS) imaging data show conclusively that both optically bright galaxies are in the foreground at z <6. A new lensing model based on the Hubble imaging data and the millimeter-wave continuum emission yields a magnification factor of 2.2 +/- 0.3, with a 95% confidence upper limit on the magnification of 3.5. When corrected for lensing, the instantaneous star formation rate is 1320M(circle dot) yr(-1), with the 95% confidence lower limit around 830M(circle dot) yr(-1). The dust and stellar masses of HFLS3 from the same spectral energy distribution (SED) models are at the level of 3x10(8) M-circle dot and similar to 5x10(10) M-circle dot, respectively, with large systematic uncertainties on assumptions related to the SED model. With Hubble/WFC3 images, we also find diffuse near-IR emission about 0.5 arcsec (similar to 3 kpc) to the southwest of HFLS3 that remains undetected in the ACS imaging data. The emission has a photometric redshift consistent with either z similar to 6 or a dusty galaxy template at z similar to 2.