Probing the photoionised outflow in the NLS1 Arakelian 564: An XMM-Newton view

We present a detailed analysis of XMM-Newton X-ray observations of the narrow-line Seyfert-1 (NLS1) galaxy Ark 564, taken between 2000 and 2011. High-resolution X-ray spectroscopy was carried out on the resultant high signal-to-noise stacked spectrum. We find three separate photoionised warm absorbers, which outflow at velocities unusually lower than typical NLS1s. Using recombination timescale estimates, improved constraints on the location of these clouds show they could be located beyond 4 pc from the central source. Our estimates of the outflow kinetics suggest that the active galactic nucleus in Ark 564 is unlikely to affect the host galaxy in its current state, but over a typical lifetime of 10⁷ yr the interstellar medium could be affected. The individual observations used here suggest the luminosity varies over weekly timescales and, in addition, we find evidence of gas response to changes in the ionising radiation.