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

The Seyfert 1 nucleus of NGC 4395 is energized by a black hole of mass 3.6×10⁵ M_solar, making it one of only two nuclear black holes of intermediate mass, 10³-10⁶ M_solar, detected in the radio regime. Building on UV and X-ray evidence for outflows from this Seyfert nucleus, the VLBI High Sensitivity Array was used at 1.4 GHz to search for extended structure on scales greater than 5 mas (0.1 pc). Elongated emission was discovered, extending over 15 mas (0.3 pc) and suggesting an outflow on subparsec scales from this intermediate-mass black hole. The Seyfert nucleus is located at the center of an elliptical star cluster, and the elongation position angle of the subparsec radio structure is only 19° from the star cluster's minor axis.