Dust-obscured Galaxies with Broken Power-law Spectral Energy Distributions Discovered by UNIONS

Abstract

We report on the spectral energy distributions (SEDs) of infrared-bright dust-obscured galaxies (DOGs) with $(i-[22]{)}_{\mathrm{AB}}\ge 7.0$. Using photometry from the deep and wide Ultraviolet Near-Infrared Optical Northern Survey, combined with near-IR and mid-IR data from the UKIRT Infrared Deep Sky Survey and the Wide-field Infrared Survey Explorer, we successfully identified 382 DOGs in $\sim$ 170 deg${}^2$. Among them, the vast majority (376 DOGs) were classified into two subclasses: bump DOGs (132/376) and power-law (PL) DOGs (244/376), which are dominated by star formation and active galactic nucleus (AGN), respectively. Through the SED analysis, we found that roughly half (120/244) of the PL DOGs show ``broken'' power-law SEDs. The significant red slope from optical to near-IR in the SEDs of these ``broken power-law DOGs'' (BPL DOGs) probably reflects their large amount of dust extinction. In other words, BPL DOGs are more heavily obscured AGNs, compared to PL DOGs with non-broken power-law SEDs.

13 pages, 10 figures, 2 tables, accepted for publication in ApJ

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• Dense Ionized Outflow with Five Narrow Components in a Dust-obscured Galaxy
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