Was 49b: An Overmassive AGN in a Merging Dwarf Galaxy?

Journal Article · Mon Feb 20 04:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/836/2/183· OSTI ID:22869331

Secrest, Nathan J.; Rothberg, Barry ^[1]; Schmitt, Henrique R.; Fischer, Jacqueline ^[2]; Blecha, Laura ^[3]

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1. National Academy of Sciences NRC Research Associate, 2101 Constitution Ave. NW, Washington, DC 20418 (United States)
2. Naval Research Laboratory, Remote Sensing Division, 4555 Overlook Ave. SW, Washington, DC 20375 (United States)
3. University of Maryland Dept. of Astronomy, 1113 PSC, Bldg. 415, College Park, MD 20742 (United States)

We present a combined morphological and X-ray analysis of Was 49, an isolated, dual-AGN system notable for the presence of a dominant AGN, Was 49b, in the disk of the primary galaxy, Was 49a, at a projected radial distance of 8 kpc from the nucleus. Using X-ray data from Chandra, the Nuclear Spectroscopic Telescope Array, and Swift, we find that this AGN has a bolometric luminosity of L {sub bol} ∼ 10{sup 45} erg s{sup −1}, with a black hole mass of M{sub BH} = 1.3{sub −0.9}{sup +2.9}×10{sup 8} M{sub ⊙}. Despite the large mass, our analysis of optical data from the Discovery Channel Telescope shows that the supermassive black hole (SMBH) is hosted by a stellar counterpart with a mass of only 5.6{sub −2.6}{sup +4.9}×10{sup 9} M{sub ⊙}, which makes the SMBH potentially larger than expected from SMBH–galaxy scaling relations, and the stellar counterpart exhibits a morphology that is consistent with dwarf elliptical galaxies. Our analysis of the system in the r and K bands indicates that Was 49 is a minor merger, with the mass ratio of Was 49b to Was 49a between ∼1:7 and ∼1:15. This is in contrast with findings that the most luminous merger-triggered AGNs are found in major mergers and that minor mergers predominantly enhance AGN activity in the primary galaxy.

• OSTI ID: 22869331
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 836; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
BOLOMETERS
DISTANCE
GALAXY NUCLEI
INTERACTIONS
LUMINOSITY
MASS
SEYFERT GALAXIES
TELESCOPES
X RADIATION