NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-08-20 T22:29:08 PDT
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For refcode 2014MNRAS.441.2613L:
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NED Abstract

Copyright by Royal Astronomical Society. 2014MNRAS.441.2613L Warm absorbers in X-rays (WAX), a comprehensive high-resolution grating spectral study of a sample of Seyfert galaxies - I. A global view and frequency of occurrence of warm absorbers. Laha, Sibasish; Guainazzi, Matteo; Dewangan, Gulab C.; Chakravorty, Susmita; Kembhavi, Ajit K. Abstract. We present results from a homogeneous analysis of the broad-band 0.3-10 keV CCD resolution as well as of the soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 Seyfert galaxies observed with XMM-Newton. Our goal is to characterize warm absorbers (WAs) along the line of sight to the active nucleus. We significantly detect WAs in 65 per cent of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates. We find a gap in the distribution of the ionization parameter in the range 0.5 < logi < 1.5 which we interpret as a thermally unstable region for WA clouds. This may indicate that the WA flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe Kalpha lines are similar to those sources which do not have broadened emission lines. Therefore, the detected broad Fe Kalpha emission lines are bona fide and not artefacts of ionized absorption in the soft X-rays. The WA parameters show no correlation among themselves, with the exception of the ionization parameter versus column density. The shallow slope of the log xi versus log v_out_ linear regression (0.12 +/- 0.03) is inconsistent with the scaling laws predicted by radiation or magnetohydrodynamic-driven winds. Our results also suggest that WA and ultra fast outflows do not represent extreme manifestation of the same astrophysical system. Key words: galaxies: active, quasars: absorption lines, quasars: emission lines, quasars: general, galaxies: Seyfert, X-rays: galaxies
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