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arXiv · 1510.08854

An Off-Nucleus Nonstellar Black Hole in the Seyfert Galaxy NGC 5252

Minjin Kim·Luis C. Ho·Junfeng Wang·Giuseppina Fabbiano·Stefano Bianchi·Massimo Cappi·Mauro Dadina·Giuseppe Malaguti·Chen Wang
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Abstract

We report the discovery of a ultraluminous X-ray source (ULX; CXO J133815.6+043255) in NGC 5252. This ULX is an off-nuclear point-source, which is 22$^{\prime\prime}$ away from the center of NGC 5252, and has an X-ray luminosity of 1.5 $\times$ $10^{40}$erg s$^{-1}$. It is one of the rare examples of ULX, which exhibits clear counterparts in radio, optical, UV bands. Follow-up optical spectrum of the ULX shows strong emission lines. The redshift of [O III] emission line coincides with the systematic velocity of NGC 5252, suggesting the ULX is gravitationally bound to NGC 5252. The flux of [O III] appears to be correlated with both X-ray and radio luminosity in the same manner as ordinary AGNs, indicating that the [O III] emission is intrinsically associated with the ULX. Based on the multiwavelength data, we argue that the ULX is unlikely to be a background AGN. A more likely option is an accreting BH with a black hole mass of $\geq 10^4M_\odot$, which might be a stripped remnant of a merging dwarf galaxy.

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Minjin Kim, Luis C. Ho, Junfeng Wang, Giuseppina Fabbiano, Stefano Bianchi, Massimo Cappi, Mauro Dadina, Giuseppe Malaguti, Chen Wang. 2015-10-29. An Off-Nucleus Nonstellar Black Hole in the Seyfert Galaxy NGC 5252. https://doi.org/10.1088/0004-637x%2F814%2F1%2F8

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