ALMA Confirmation of Millimeter Time Variability in the Gamma-Ray Detected Seyfert Galaxy GRS 1734-292

ABSTRACT :
GRS 1734-292, a radio-quiet Seyfert galaxy, was detected in the gamma-ray band by Fermi-LAT. Atacama Large Millimeter/submillimeter Array observations at 97.5, 145, and 225 GHz revealed a millimeter excess in the central ~100 pc region, with variability over 4 days. This suggests a compact source smaller than <100 Schwarzschild radius. The spectrum indicates a coronal magnetic field of ≈10 G and a size of ≈10 Schwarzschild radius, or possibly emission from disk winds. Future higher-resolution observations will clarify the emission source and particle acceleration in radio-quiet Seyfert galaxies.