Exploring the nuclear environment of the NLS1 galaxy Arakelian 564 with XMM-Newton RGS

Aims. We present an accurate characterisation of the high-resolution X-ray spectrum of the Narrow Line Seyfert 1 galaxy Arakelian 564 and put it in to context with other objects of its type by making a detailed comparison of their spectra. Methods. The data are taken from 5 observations with the XMM-Newton Reflection Grating Spectrometer and fitted with various spectral models. Results. The best fit to the data identifies five significant emission lines at 18.9, 22.1, 24.7, 29.0 and 33.5 (A) over circle due to OVIII Ly alpha, OVII(f), NVII Ly alpha, NVI(i) and CVI Ly alpha respectively. These have an RMS velocity of similar to 1100 km s(-1) and a flow velocity of similar to-600 km s(-1), except for the OVII(f) emission line, which has a flow velocity consistent with zero. Two separate emitting regions are identified. Three separate phases of photoionized, X-ray absorbing gas are included in the fit with ionization parameters log xi = -0.86, 0.87, 2.56 and column densities N-H = 0.89, 2.41, 6.03 x 10(20) cm(-2) respectively. All three phases show this to be an unusually low velocity outflow (- 10 +/- 100 km s(-1)) for a narrow line Seyfert 1. We present the hypothesis that the BLR is the source of the NLR and warm absorber, and examine optical and UV images from the XMM-Newton Optical Monitor to relate our findings to the characteristics of the host galaxy.