Selection and Mid-infrared Spectroscopy of Ultraluminous Star-forming Galaxies at z ~ 2
Fang, Guanwen; Kong, Xu; Willner, S. P.; Chen, Yang; Wang, Tao; Huang, Jia-Sheng; Lin, Xuanbin
China, Chile, United States, Italy
Abstract
Starting from a sample of 24 μm sources in the Extended Groth Strip, we use 3.6-8 μm color criteria to select ultraluminous infrared galaxies (ULIRGs) at z ~ 2. Spectroscopy from 20-38 μm of 14 objects verifies their nature and gives their redshifts. Multi-wavelength data for these objects imply stellar masses >1011 M ⊙ and star formation rates >=410 M ⊙ yr-1. Four objects of this sample observed at 1.6 μm (rest-frame visible) with Hubble Space Telescope/WFC3 show diverse morphologies, suggesting that multiple formation processes create ULIRGs. Of the 14 objects, 4 show signs of active galactic nuclei, but the luminosity appears to be dominated by star formation in all cases.