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The XMM–Newton Bright Survey sample of absorbed quasars: X-ray and accretion properties

Abstract: Although absorbed quasars are extremely important for our understanding of the energetics of the Universe, the main physical parameters of their central engines are still poorly known. In this work, we present and study a complete sample of 14 quasars (QSOs) that are absorbed in the X-rays (column density NH > 4 × 1021?cm-2 and X-ray luminosity L?2-10?keV > 1044?ergs-1; XQSO2) belonging to the XMM–Newton Bright Serendipitous Survey (XBS). From the analysis of their ultraviolet-to-mid-infrared spectral energy distribution, we can separate the nuclear emission from the host galaxy contribution, obtaining a measurement of the fundamental nuclear parameters, like the mass of the central supermassive black hole and the value of Eddington ratio, ??Edd. Comparing the properties of XQSO2s with those previously obtained for the X-ray unabsorbed QSOs in the XBS, we do not find any evidence that the two samples are drawn from different populations. In particular, the two samples span the same range in Eddington ratios, up to ??Edd ~ 0.5; this implies that our XQSO2s populate the ‘forbidden region’ in the so-called ‘effective Eddington limit paradigm’. A combination of low grain abundance, presence of stars inwards of the absorber, and/or anisotropy of the disc emission can explain this result.

Otras publicaciones de la misma revista o congreso con autores/as de la Universidad de Cantabria

 Fuente: Monthly Notices of the Royal Astronomical Society, vol. 444, iss.3, Pp. 2580-2598 (2014)

Editorial: Oxford University Press

 Fecha de publicación: 01/11/2014

Nº de páginas: 19

Tipo de publicación: Artículo de Revista

 DOI: 10.1093/mnras/stu1628

ISSN: 0035-8711,1365-2966

Proyecto español: AYA2012-31447

Url de la publicación: https://doi.org/10.1093/mnras/stu1628