AN XMM-NEWTON OBSERVATION OF THE SEYFERT 1 GALAXY 1H 0419-577 IN AN EXTREME LOW STATE

摘要

Previous observations of the luminous Seyfert 1 galaxy 1H 0419 ― 577 have found its X-ray spectrum to range from that of a typical Seyfert 1 galaxy with a 2-10 keV power-law index of Γ ～ 1.9 to a much flatter power law of Γ ～ 1.5 or less. We report here a new XMM-Newton observation that allows the low-state spectrum to be studied in much greater detail than hitherto. We find a very hard spectrum (Γ ～ 1.0), which exhibits broad features that can be modeled with the addition of an extreme relativistic Fe K emission line or with partial covering of the underlying continuum by a substantial column density of near-neutral gas. Both the EPIC and Reflection Grating Spectrometer (RGS) data show evidence for strong line emission of O Ⅶ and O Ⅷ requiring an extended region of low-density photoionized gas in 1H 0419-577. Comparison with an earlier XMM-Newton observation when 1H 0419-577 was "X-ray-bright" indicates that the dominant spectral variability occurs via a steep power-law component.