GH 10 is a broad-lined active galactic nucleus ( AGN ) energized by a black hole of mass 800,000 M _ { \odot } .
It was the only object detected by Greene et al .
in their Very Large Array ( VLA ) survey of 19 low-mass AGNs discovered by Greene & Ho .
New VLA imaging at 1.4 , 4.9 , and 8.5 GHz reveals that GH 10 ’ s emission has an extent of less than 320 pc , has an optically-thin synchrotron spectrum with a spectral index \alpha = -0.76 \pm 0.05 ( S _ { \nu } \propto \nu ^ { + \alpha } ) , is less than 11 % linearly polarized , and is steady - although poorly sampled - on timescales of weeks and years .
Circumnuclear star formation can not dominate the radio emission , because the high inferred star formation rate , 18 M _ { \odot } yr ^ { -1 } , is inconsistent with the rate of less than 2 M _ { \odot } yr ^ { -1 } derived from narrow H \alpha and [ O II ] \lambda 3727 emission .
Instead , the radio emission must be mainly energized by the low-mass black hole .
GH 10 ’ s radio properties match those of the steep-spectrum cores of Palomar Seyfert galaxies , suggesting that , like those Seyferts , the emission is outflow-driven .
Because GH 10 is radiating close to its Eddington limit , it may be a local analog of the starting conditions , or seeds , for supermassive black holes .
Future imaging of GH 10 at higher linear resolution thus offers an opportunity to study the relative roles of radiative versus kinetic feedback during black-hole growth .