SDSS IV MaNGA: Discovery of an Hα Blob Associated with a Dry Galaxy Pair—Ejected Gas or a “Dark” Galaxy Candidate?

Journal Article · Wed Mar 01 00:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/837/1/32· OSTI ID:22869292

Lin, Lihwai; Lin, Jing-Hua; Hsu, Chin-Hao ^[1]; Fu, Hai ^[2]; Huang, Song; Cheung, Edmond; Peirani, Sébastien; Rujopakarn, Wiphu; Stark, David V.; Bundy, Kevin ^[3]; Sánchez, Sebastián F. ^[4]; Gwyn, Stephen ^[5]; Gelfand, Joseph D. ^[6]; Masters, Karen ^[7]; Belfiore, Francesco; Bothwell, M. S. ^[8]; Hagen, Alex ^[9]; Hao, Lei ^[10]; Huang, Shan ^[11]; Law, David ^[12] ; others, and

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1. Institute of Astronomy and Astrophysics, Academia Sinica, Taipei 10617, Taiwan (China)
2. Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242 (United States)
3. Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)
4. Instituto de Astronomía, Universidad Nacional Autonóma de Mexico, A.P. 70-264, 04510, México, D.F. (Mexico)
5. NRC-Herzberg Astronomy and Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7 (Canada)
6. NYU Abu Dhabi, P.O. Box 129188, Abu Dhabi (United Arab Emirates)
7. Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth, PO1 3FX (United Kingdom)
8. Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)
9. Dept. of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
10. Shanghai Astronomical Observatory, Chinese Academy of Science, 80 Nandan Road, Shanghai 200030 (China)
11. Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)
12. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

We report the discovery of a mysterious giant Hα blob that is ∼8 kpc away from the main MaNGA target 1-24145, one component of a dry galaxy merger, and has been identified in the first-year SDSS-IV MaNGA data. The size of the Hα blob is ∼3–4 kpc in radius, and the Hα distribution is centrally concentrated. However, there is no optical continuum counterpart in the deep broadband images reaching ∼26.9 mag arcsec{sup −2} in surface brightness. We estimate that the masses of the ionized and cold gases are 3.3×10{sup 5} M{sub ⊙} and <1.3×10{sup 9} M{sub ⊙}, respectively. The emission-line ratios indicate that the Hα blob is photoionized by a combination of massive young stars and AGNs. Furthermore, the ionization line ratio decreases from MaNGA 1-24145 to the Hα blob, suggesting that the primary ionizing source may come from MaNGA 1-24145, likely a low-activity AGN. Possible explanations for this Hα blob include the AGN outflow, the gas remnant being tidally or ram-pressure stripped from MaNGA 1-24145, or an extremely low surface brightness galaxy. However, the stripping scenario is less favored according to galaxy merger simulations and the morphology of the Hα blob. With the current data, we cannot distinguish whether this Hα blob is ejected gas due to a past AGN outburst, or a special category of “ultra-diffuse galaxy” interacting with MaNGA 1-24145 that further induces the gas inflow to fuel the AGN in MaNGA 1-24145.

• OSTI ID: 22869292
• Journal Information: Astrophysical Journal, Vol. 837, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BRIGHTNESS
COMPUTERIZED SIMULATION
DISTRIBUTION
EMISSION
GALACTIC EVOLUTION
GALAXIES
MASS
PHOTOIONIZATION
STARS
SURFACES