Detection of the “Active” Nucleus of M32

Abstract

M32 hosts a 2.5×106 Msolar central black hole, but signs of nuclear activity in this galaxy have long eluded detection. We report the first conclusive detection of the nucleus of M32 in X-rays, based on high-resolution, sensitive observations made with Chandra. The 2-10 keV luminosity is merely 9.4×1035 ergs s-1, ~3×10-9 times the Eddington luminosity of the black hole. Weak diffuse emission, consistent with thermal gas at a temperature of 0.37 keV, is seen in an annular region ~100 pc from the center. We also present a deep, moderately high-resolution (0.9") radio continuum observation obtained with the Very Large Array, which places a tight upper bound on the nuclear radio power at 8.4 GHz. We combine these new measurements with upper limits at other wavelengths to discuss implications for the nature of accretion onto the central black hole.