paper

Discovery of An Active Intermediate-Mass Black Hole Candidate in the Barred Bulgeless Galaxy NGC 3319

arXiv:1810.10283 · doi:10.3847/1538-4357/aaeb90

Abstract

We report the discovery of an active intermediate-mass black hole (IMBH) candidate in the center of nearby barred bulgeless galaxy . The point X-ray source revealed by archival Chandra and XMM-Newton observations is spatially coincident with the optical and UV galactic nuclei from Hubble Space Telescope observations. The spectral energy distribution derived from the unresolved X-ray and UV-optical flux is comparable with active galactic nuclei (AGNs) rather than ultra-luminous X-ray sources, although its bolometric luminosity is only . Assuming an Eddington ratio range between 0.001 and 1, the black hole mass ($M_\rm{BH}$) will be located at , placing it in the so-called IMBH regime and could be the one of the lowest reported so far. Estimates from other approaches (e.g., fundamental plane, X-ray variability) also suggest $M_\rm{BH}\lesssim10^5~M_{\odot}$.Similar to other BHs in bulgeless galaxies, the discovered IMBH resides in a nuclear star cluster with mass of . The detection of such a low-mass BH offers us an ideal chance to study the formation and early growth of SMBH seeds, which may result from the bar-driven inflow in late-type galaxies with a prominent bar such as .

arXiv commentApJ accepted, 2 tables, 6 figures

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