Investigating the origin of the Fe emission lines of the Seyfert 1 galaxy Mrk 205

Abstract

ABSTRACT We have investigated the nature and origin of the Fe K emission lines in Mrk 205 using observations with Suzaku and XMM–Newton, aiming to resolve the ambiguity between a broad emission line and multiple unresolved lines of higher ionization. We detect the presence of a narrow Fe K α emission line along with a broad-band Compton reflection hump at energies $E\gt 10\rm \, \, {\rm keV}$. These are consistent with reflected emission of hard X-ray photons off a Compton-thick material of $N_{\rm H}\ge 2.15\times 10^{24}\rm \, \, {\rm cm^{-2}}$. In addition we detect a partially covering ionized absorption with ionization parameter $\log (\xi /\rm \, erg\, cm\, s^{-1})=1.9_{-0.5}^{+0.1}$, column density $N_{\rm H}=(5.6_{-1.9}^{+2.0})\times 10^{22}\rm \, \, {\rm cm^{-2}}$, and a covering factor of $0.22_{-0.06}^{+0.09}$. We detect the presence of emission arising out of ionized disc reflection contributing in the soft and hard X-rays consistently in all the observations. We however, could not definitely ascertain the presence of a relativistically broadened Fe line in the X-ray spectra. Using relativistic reflection models, we found that the data are unable to statistically distinguish between the scenarios when the supermassive black hole is non-rotating and when it is maximally spinning. Using the disc reflection model we also find that the accretion disc of the active galactic nucleus may be truncated at a distance 6RG < R < 12RG, which may suggest why there may not be any broad Fe line. The Eddington rate of the source is low (λEdd = 0.03), which points to an inefficient accretion, possibly due to a truncated disc.