Dust-Obscured Galaxies in the Local Universe

TL;DR

This study identifies and characterizes 47 local dust-obscured galaxies (DOGs) using infrared and ultraviolet data, revealing their similarities to high-redshift DOGs and suggesting diverse physical mechanisms behind dust obscuration.

Contribution

The paper presents the first detailed analysis of local DOGs, comparing their properties to high-z counterparts, and highlights their diverse morphologies and physical origins.

Findings

Local DOGs have similar properties to high-z DOGs despite lower IR luminosities.

Many local DOGs show no signs of recent interactions or companions.

Physical mechanisms behind dust obscuration are diverse, not indicating a single evolutionary phase.

Abstract

We use Wide-field Infrared Survey Explorer (WISE), AKARI, and Galaxy Evolution Explorer (GALEX) data to select local analogs of high-redshift (z~2) dust obscured galaxies (DOGs). We identify 47 local DOGs with S_{12\mu m}/S_{0.22 \mu m}>892 and S_{12\mu m}>20 mJy at 0.05<z<0.08 in the Sloan Digital Sky Survey data release 7. The infrared luminosities of these DOGs are in the range 3.4x10^{10} (L_\odot)<L_{IR}<7.0x10^{11} (L_\odot) with a median L_{IR} of 2.1x10^{11} (L_\odot). We compare the physical properties of local DOGs with a control sample of galaxies that have lower $S_{12\mu m}/S_{0.22 \mu m}$ but have similar redshift, IR luminosity, and stellar mass distributions. Both WISE 12 micron and GALEX near-ultraviolet (NUV) flux densities of DOGs differ from the control sample of galaxies, but the difference is much larger in the NUV. Among the 47 DOGs, 36\pm7% have small axis ratios in the optical (i.e., b/a<0.6), larger than the fraction among the control sample (17\pm3%). There is no obvious sign of interaction for many local DOGs. No local DOGs have companions with comparable optical magnitudes closer than ~50 kpc. The large- and small-scale environments of DOGs are similar to the control sample. Many physical properties of local DOGs are similar to those of high-z DOGs, even though the IR luminosities of local objects are an order of magnitude lower than for the high-z objects: the presence of two classes (active galactic nuclei- and star formation-dominated) of DOGs, abnormal faintness in the UV rather than extreme brightness in the mid-infrared, and diverse optical morphology. These results suggest a common underlying physical origin of local and high-z DOGs. Both seem to represent the high-end tail of the dust obscuration distribution resulting from various physical mechanisms rather than a unique phase of galaxy evolution.