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Extreme Nature of F...
Extreme Nature of Four Blue-excess Dust-obscured Galaxies Revealed by Optical Spectroscopy
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- Noboriguchi, Akatoki (author)
- Ehime University,Tohoku University
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- Nagao, Tohru (author)
- Ehime University
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- Toba, Y. (author)
- Academia Sinica Taiwan,Kyoto University,Ehime University,National Astronomical Observatory of Japan
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- Ichikawa, Kohei (author)
- Tohoku University
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- Kajisawa, Masaru (author)
- Ehime University
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- Kato, Nanako (author)
- Ehime University
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Kawaguchi, Toshihiro (author)
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- Matsuhara, Hideo (author)
- The Graduate University for Advanced Studies (SOKENDAI)
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- Matsuoka, Yoshiki (author)
- Ehime University
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- Onishi, Kyoko, 1989 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Onoue, Masafusa (author)
- University of Tokyo, Japan,Beijing University of Technology,Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
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- Tamada, Nozomu (author)
- Ehime University
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- Terao, Koki (author)
- National Astronomical Observatory of Japan,Tohoku University
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- Terashima, Yuichi (author)
- Ehime University
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- Ueda, Yoshihiro (author)
- Kyoto University
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- Yamashita, Takuji (author)
- National Astronomical Observatory of Japan,Ehime University
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(creator_code:org_t)
- 2022-12-23
- 2022
- English.
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In: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 941:2
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Abstract
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- We report optical spectroscopic observations of four blue-excess dust-obscured galaxies (BluDOGs) identified by the Subaru Hyper Suprime-Cam. BluDOGs are a subclass of dust-obscured galaxies (DOGs; defined with the extremely red color (i − [22])AB ≥ 7.0; Toba et al., showing a significant flux excess in the optical g and r bands over the power-law fits to the fluxes at the longer wavelengths. Noboriguchi et al. have suggested that BluDOGs may correspond to the blowing-out phase involved in a gas-rich major-merger scenario. However, the detailed properties of BluDOGs are not understood because of the lack of spectroscopic information. In this work, we carry out deep optical spectroscopic observations of four BluDOGs using Subaru/FOCAS and VLT/FORS2. The obtained spectra show broad emission lines with extremely large equivalent widths, and a blue wing in the C iv line profile. The redshifts are between 2.2 and 3.3. The averaged rest-frame equivalent widths of the C iv lines are 160 ± 33 Å, ∼7 times higher than the average of a typical type 1 quasar. The FWHMs of their velocity profiles are between 1990 and 4470 km s−1, and their asymmetric parameters are 0.05 and 0.25. Such strong C iv lines significantly affect the broadband magnitudes, which are partly the origin of the blue excess seen in the spectral energy distribution of BluDOGs. Their estimated supermassive black hole masses are 1.1 × 108 < M BH/M ⊙ <5.5 × 108. The inferred Eddington ratios of the BluDOGs are higher than 1 (1.1 < λ Edd < 3.8), suggesting that the BluDOGs are in a rapidly evolving phase of supermassive black holes.
Subject headings
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
- NATURVETENSKAP -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)
- NATURVETENSKAP -- Fysik -- Den kondenserade materiens fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Condensed Matter Physics (hsv//eng)
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Noboriguchi, Aka ...
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Nagao, Tohru
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Toba, Y.
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Ichikawa, Kohei
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Kajisawa, Masaru
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Kato, Nanako
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Kawaguchi, Toshi ...
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Matsuhara, Hideo
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Matsuoka, Yoshik ...
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Onishi, Kyoko, 1 ...
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Onoue, Masafusa
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Tamada, Nozomu
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Terao, Koki
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Terashima, Yuich ...
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Ueda, Yoshihiro
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Yamashita, Takuj ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
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and Astronomy Astrop ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
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and Atom and Molecul ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
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and Condensed Matter ...
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Chalmers University of Technology