Search for Hyper Infrared-Luminous Dust Obscured Galaxies selected with WISE and SDSS

TL;DR

This study identifies hyper infrared-luminous dust-obscured galaxies (HyLIRGs) using SDSS and WISE data, revealing their properties, abundance, and potential for understanding galaxy evolution.

Contribution

It introduces a new selection method for HyLIRGs based on IR-bright DOGs, expanding the known population and providing insights into their luminosity and distribution.

Findings

24 HyLIRGs discovered among spectroscopically confirmed DOGs

IR-bright DOGs' color correlates with IR luminosity

Surface density of HyLIRGs exceeds 0.17 per square degree

Abstract

We aim to search for hyperliminous infrared (IR) galaxies (HyLIRGs) with IR luminosity $L_{{\rm IR}}$ $>$ 10$^{13}$ $L_{\odot}$ by applying the selection method of Dust Obscured Galaxies (DOGs). They are spatially rare but could correspond to a maximum phase of cosmic star formation and/or active galactic nucleus (AGN) activity, hence they are a crucial population for understanding the star formation and mass assembly history of galaxies. Combining the optical and IR catalogs obtained from Sloan Digital Sky Survey (SDSS) and Wide-field Infrared Survey Explorer (WISE), we performed the extensive HyLIRGs survey; we selected 5,311 IR-bright DOGs with $i$ -- [22] $>$ 7.0 and flux at 22 $\mu$m $>$ 3.8 mJy in 14,555 deg$^2$, where $i$ and [22] are $i$-band and 22 $\mu$m AB magnitudes, respectively. Among them, 67 DOGs have reliable spectroscopic redshifts that enable us to estimate their total IR luminosity based on the SED fitting. Consequently, we successfully discovered 24 HyLIRGs among the 67 spectroscopically-confirmed DOGs. We found that (i) $i$ - [22] color of IR-bright DOGs correlates with the total IR luminosity and (ii) surface number density of HyLIRGs is $>$ 0.17 deg$^{-2}$. A high fraction ($\sim$ 73%) of IR-bright DOGs with $i$ - [22] $>$ 7.5 shows $L_{{\rm IR}}$ $>$ 10$^{13}$ $L_{\odot}$, and the DOGs criterion we adopted could be independently-effective against "W1W2-dropout method" based on four WISE bands, for searching hyper IR luminous populations of galaxies.