Testing current synthesis models of the X-ray background

By R. Gilli, M. Salvati, G. Hasinger. 2000

194 citations recorded by the source corpus.

We present synthesis models of the X-ray background where the available X-ray observational constraints are used to derive information on the AGN population properties. We show the need for luminous X-ray absorbed AGNs, the QSO2s, in reproducing the 2-10 keV source counts at relatively bright fluxes. We compare a model where the evolution of absorbed AGNs is faster than that of unabsorbed ones, with a standard model where absorbed and unabsorbed AGNs evolve at the same rate. It is found that an increase by a factor of ~2 from z=0 to z~1.3 in the ratio between absorbed and unabsorbed AGNs would provide a significant improvement in the data description. Finally, we make predictions on the AGNs to be observed in deep X-ray surveys which contain information on the AGN space density at high redshift.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/1cb3efd8eea62446148d952731e89f122304d43f

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Citations in the corpus

The FIRST-2MASS Red Quasar Survey (2007, methodology): “It has also been successful at predicting AGN number counts in the infrared and explaining the shape of the extragalactic X-ray background (e.g., Madau et al. 1994; Comastri et al. 1995; Gilli et al. 2001; Ueda et al. 2003; Treister et al. 2004, 2006; Treister & Urry 2005).”
Unveiling Obscured Accretion in the Chandra Deep Field-South (2007, background): “Compton thick objects may well be more common at high redshift, as suggested on theoretical ground by Silk & Rees (1998) and Fabian (1999) and on observational ground by e.g. Gilli et al. (2001), Worsley et al. (2004, 2006), and La Franca et al. (2005).”
A Unified, Merger-driven Model of the Origin of Starbursts, Quasars, the Cosmic X-Ray Background, Supermassive Black Holes, and Galaxy Spheroids (2005, background): “Indeed, population synthesis models based on observed quasar luminosity functions and involving large numbers of obscured AGN have been successful at matching both the X-ray background intensity and spectral shape (Madau et al. 1994; Comastri et al. 1995; Gilli et al. 1999, 2001).”
Evidence for Quasar Activity Triggered by Galaxy Mergers in HST Observations of Dust-reddened Quasars (2007, background): “%) of the accretion process in AGNs is obscured and only themost energetic photons (>20 keV) can penetrate the obscuring dust barrier (Gilli et al. 2001, 2007; Ueda et al. 2003).”
The HELLAS2XMM Survey. VII. The Hard X-Ray Luminosity Function of AGNs up to z = 4: More Absorbed AGNs at Low Luminosities and High Redshifts (2005, background): “875No. 2, 2005 we note that an increasing ratio between absorbed and unabsorbed AGNs toward high redshifts has already been included in the synthesis models of Pompilio et al. (2000) and Gilli et al. (2001), although with a different prescription for the absorption distribution.”
The Chandra Deep Field North Survey. VI. The Nature of the Optically Faint X-Ray Source Population (2001, background): “The population synthesis model of Gilli et al. (2001) predicts that obscured QSOs contribute≈ 30% of the hard X-ray background.”
The 2-10 keV luminosity as a Star Formation Rate indicator (2002, result): “The latter are essentially in agreement with the results of more recent synthesis models (Gilli et al. 2001).”
The ROSAT Deep Survey - VI. X-ray sources and Optical identifications of the Ultra Deep Survey (2001, unknown): “For example, Gilli et al. (2001) have recently shown that the redshift distribution of type I and type II AGN for a sub-sample of the UDS sources is statistically consistent with models in which the fraction of obscured AGN is constant with luminosity.”