http://arxiv.org/abs/1606.01268
There is mounting evidence that supermassive black holes form and grow in bulgeless galaxies. However, a robust determination of the fraction of AGNs in bulgeless galaxies, an important constraint to models of supermassive black hole seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for low mass AGNs. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z=0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3 sigma level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of L{2-10~keV}=1.1+/-0.4 10^40 ergs/s. Ground-based near-infrared spectroscopy with the Large Binocular Telescope together with multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of ~NH >10^24 cm^-2. The hard X-ray luminosity of the putative AGN corrected for absorption is L{2-10~keV}~3×10^42 ergs/s, which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of 6×10^43ergs/s – 3×10^44 erg/s, and a lower mass limit for the black hole of MBH~2×10^6 Msun, based on the Eddington limit.
S. Satyapal, N. Secrest, B. Rothberg, et. al.
Tue, 7 Jun 16
15/80
Comments: Accepted to ApJ, 14 pages, 7 figures
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