Suzaku observations of Mrk 335: Confronting partial covering and relativistic reflection

L. C. Gallo, D. R. Wilkins, K. Bonson, C-Y. Chiang, D. Grupe, M. L. Parker, A. Zoghbi, A. C. Fabian, S. Komossa, A. L. Longinotti, 2014. MNRAS 446, 633-650

We report on the deepest X-ray observation of the narrow-line Seyfert 1 galaxy Mrk 335 in the low-flux state obtained with Suzaku. The data are compared to a 2006 high-flux Suzaku observation when the source was ~10-times brighter. Describing the two flux levels self-consistently with partial covering models would require extreme circumstances, as the source would be subject to negligible absorption during the bright state and ninety-five per cent covering with near Compton-thick material when dim. Blurred reflection from an accretion disc around a nearly maximum spinning black hole (a>0.91, with preference for a spin parameter as high as ~ 0.995) appears more likely and is consistent with the long-term and rapid variability. Measurements of the emissivity profile and spectral modelling indicate the high-flux Suzaku observation of Mrk 335 is consistent with continuum-dominated, jet-like emission (i.e. beamed away from the disc). It can be argued that the ejecta must be confined to within ~25 rg if it does not escape the system. During the low-flux state the corona becomes compact and only extends to about 5 rg from the black hole, and the spectrum becomes reflection-dominated. The low-frequency lags measured at both epochs are comparable indicating that the accretion mechanism is not changing between the two flux levels. Various techniques to study the spectral variability (e.g. principal component analysis, fractional variability, difference spectra, and hardness ratio analysis) indicate that the low-state variability is dominated by changes in the power law flux and photon index, but that changes in the ionisation state of the reflector are also required. Most notably, the ionisation parameter becomes inversely correlated with the reflected flux after a long-duration flare-like event during the observation.