Revealing a hard X-ray spectral component that reverberates within one light hour of the central supermassive black hole in Ark 564

M. Giustini, T. J. Turner, J. N. Reeves +4

Ark 564 (z=0.0247) is an X-ray-bright NLS1. By using advanced X-ray timing techniques, an excess of "delayed" emission in the hard X-ray band (4-7.5 keV) following about 1000 secon…