An XMM-Newton observation of the luminous Seyfert 1 galaxy Markarian 509

We present the spectral analysis of an early XMM-Newton observation of the luminous Seyfert 1 galaxy Mrk 509. We find the hard (2-10 keV) continuum slope, including reflection, to be somewhat flatter (Γ = 1.75) than that of a typical broad-line Seyfert 1 galaxy. The most obvious feature in the hard X-ray spectrum is a narrow emission line near 6.4 keV with an equivalent width of ~50 eV. The energy and strength of this line is consistent with fluorescence from "neutral" iron in the molecular torus, and we note the emerging ubiquity of this feature in XMM-Newton and Chandra observations of Seyfert 1 galaxies over a wide luminosity range. We also find evidence for a second emission line at 6.7-6.9 keV, which we attempt to model by reflection from a highly ionized disk. A "soft excess," evident as an upward curvature in the continuum flux below ~1.5 keV, cannot be explained solely by enhanced reflection from the ionized disk. The RGS spectrum shows only weak discrete emission and absorption features in the soft X-ray spectrum, supporting our conclusion that the soft excess emission in Mrk 509 represents the high-energy portion of optically thick, thermal emission from the inner accretion disk.