SDSS J160531.84+174826.1: A Dwarf Disk Galaxy With An Intermediate-Mass   Black Hole
  We report the discovery of a dwarf Seyfert 1 active galactic nucleus (AGN) with a candidate intermediate-mass black hole hosted by the dwarf galaxy SDSS J160531.84+174826.1 at z=0.032. A broad component of the H-alpha line with FWHM=781 km/s is detected in its optical spectrum, and a bright, point-like nucleus is evident from a HST imaging observation. Non-thermal X-ray emission is also detected from the nucleus. The black hole mass, as estimated from the luminosity and width of the broad H-alpha component, is about 7x10^4 \msun. The host galaxy appears to be a disk galaxy with a boxy bulge or nuclear bar; with an absolute magnitude of M_R = -17.8 (M_B = -16.4), it is among the least luminous host galaxies ever identified for a Seyfert 1. 
Xiaobo Dong (1,2), Tinggui Wang (1,2), Weimin Yuan (3), Hongguang Shan   (3), Hongyan Zhou (1,2,4), Lulu Fan (1,2), Liming D...