Flaring from the supermassive black hole in Mrk 335 studied with Swift and NuSTAR

D.R. Wilkins, L.C. Gallo, D. Grupe, K. Bonson, S. Komossa and A.C. Fabian, 2015, MNRAS 454, 4440

Monitoring of the narrow line Seyfert 1 galaxy Markarian 335 (Mrk 335) with the Swift satellite discovered an X-ray flare beginning 2014 August 29. At the peak, the 0.5-5keV count rate had increased from that in the low flux state by a factor of 10. A target of opportunity observation was triggered with NuSTAR, catching the decline of the flare on 2014 September 20. We present a joint analysis of Swift and NuSTAR observations to understand the cause of this flare. The X-ray spectrum shows an increase in directly observed continuum flux and the softening of the continuum spectrum to a photon index of 2.49 (-0.07,+0.08) compared to the previous low flux observations. The X-ray spectrum remains well-described by the relativistically blurred reflection of the continuum from the accretion disc whose emissivity profile suggests that it is illuminated by a compact X-ray source, extending at most 5.2rg over the disc. A very low reflection fraction of 0.41 (-0.15,+0.15) is measured, unexpected for such a compact corona. The X-ray flare is, hence, interpreted as arising from the vertical collimation and ejection of the X-ray emitting corona at a mildly relativistic velocity, causing the continuum emission to be beamed away from the disc. As the flare subsides, the base of this jet-like structure collapses into a compact X-ray source that provides the majority of the radiation that illuminates the disc while continuum emission is still detected from energetic particles further out, maintaining the low reflection fraction.