2010ApJ...725.2444K -
Astrophys. J., 725, 2444-2460 (2010/December-3)
The XMM-Newton X-ray spectra of the most X-ray luminous radio-quiet ROSAT bright Survey-QSOs: a reference sample for the interpretation of high-redshift QSO spectra.
KRUMPE M., LAMER G., MARKOWITZ A. and CORRAL A.
Abstract (from CDS):
We present the broadband X-ray properties of four of the most X-ray luminous (LX ≥ 1045 erg/s in the 0.5-2 keV band) radio-quiet QSOs found in the ROSAT Bright Survey. This uniform sample class, which explores the extreme end of the QSO luminosity function, exhibits surprisingly homogenous X-ray spectral properties: a soft excess with an extremely smooth shape containing no obvious discrete features, a hard power law above 2 keV, and a weak narrow/barely resolved Fe Kα fluorescence line for the three high signal-to-noise ratio (S/N) spectra. The soft excess can be well fitted with only a soft power law. No signatures of warm or cold intrinsic absorbers are found. The Fe Kα centroids and the line widths indicate emission from neutral Fe (E = 6.4 keV) originating from cold material from distances of only a few light days or further out. The well-constrained equivalent widths (EW) of the neutral Fe lines are higher than expected from the X-ray Baldwin effect which has been only poorly constrained at very high luminosities. Taking into account our individual EW measurements, we show that the X-ray Baldwin effect flattens above LX∼ 1044 erg/s (2-10 keV band) where an almost constant of ∼100 eV is found. We confirm the assumption of having very similar X-ray active galactic nucleus properties when interpreting stacked X-ray spectra. Our stacked spectrum serves as a superb reference for the interpretation of low S/N spectra of radio-quiet QSOs with similar luminosities at higher redshifts routinely detected by XMM-Newton and Chandra surveys.
Abstract Copyright:
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Journal keyword(s):
galaxies: active - quasars: general - X-rays: individual (RBS 1055, RBS 320, RBS 1124, RBS 1883)
Simbad objects:
21
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