Hyper-luminous dust-obscured galaxies discovered by the Hyper Suprime-Cam on Subaru and WISE
Abstract
We present the photometric properties of a sample of infrared (IR) bright dust-obscured galaxies (DOGs). Combining wide and deep optical images obtained with the Hyper Suprime-Cam on the Subaru Telescope and all-sky mid-IR (MIR) images taken with Wide-Field Infrared Survey Explorer, we discovered 48 DOGs with i - Ks > 1.2 and i - [22] > 7.0, where i, Ks, and [22] represent AB magnitude in the i-band, Ks-band, and 22 μm, respectively, in the GAMA 14 hr field (∼ 9 deg2). Among these objects, 31 (∼ 65%) show power-law spectral energy distributions (SEDs) in the near-IR (NIR) and MIR regime, while the remainder show an NIR bump in their SEDs. Assuming that the redshift distribution for our DOGs sample is Gaussian, with mean and sigma z = 1.99 ± 0.45, we calculated their total IR luminosity using an empirical relation between 22 μm luminosity and total IR luminosity. The average value of the total IR luminosity is (3.5 ± 1.1) × 1013 L⊙, which classifies them as hyper-luminous infrared galaxies. We also derived the total IR luminosity function (LF) and IR luminosity density (LD) for a flux-limited subsample of 18 DOGs with 22 μm flux greater than 3.0 mJy and with i-band magnitude brighter than 24 AB magnitude. The derived space density for this subsample is log φ = -6.59 ± 0.11 [Mpc-3]. The IR LF for DOGs including data obtained from the literature is fitted well by a double-power law. The derived lower limit for the IR LD for our sample is ρIR ∼ 3.8 × 107 [L⊙ Mpc-3] and its contributions to the total IR LD, IR LD of all ultra-luminous infrared galaxies, and that of all DOGs are > 3%, > 9%, and > 15%, respectively.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- October 2015
- DOI:
- 10.1093/pasj/psv057
- arXiv:
- arXiv:1506.00320
- Bibcode:
- 2015PASJ...67...86T
- Keywords:
-
- catalogs;
- galaxies: active;
- galaxies: luminosity function;
- mass function;
- infrared: galaxies;
- methods: statistical;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 15 pages, 15 figures, and 3 tables, accepted for publication in PASJ (Subaru special issue)