Radio Emission on Subparsec Scales from the Intermediate-Mass Black Hole in NGC 4395

Abstract

The Seyfert 1 nucleus of NGC 4395 is energized by a black hole of mass 3.6 × 10 5 M ☉ , making it\r one of only two nuclear black holes of intermediate mass, 10 3 -10 6 M ☉ , detected in the radio\r regime. Building on UV and X-ray evidence for outflows from this Seyfert nucleus, the VLBI High\r Sensitivity Array was used at 1.4 GHz to search for extended structure on scales greater than 5 mas\r (0.1 pc). Elongated emission was discovered, extending over 15 mas (0.3 pc) and suggesting an\r outflow on subparsec scales from this intermediate-mass black hole. The Seyfert nucleus is located\r at the center of an elliptical star cluster, and the elongation position angle of the subparsec\r radio structure is only 19° from the star cluster's minor axis.