Erratum: Studying the relationship between X-ray emission and accretion in AGNs using the XMM–Newton Bright Serendipitous Survey

Abstract

We study the link between the X-ray emission in radio-quiet AGNs and the accretion rate on the central Supermassive Black Hole using a statistically well-defined and representative sample of 71 type 1 AGNs extracted from the XMM-Newton Bright Serendipitous Survey. We search and quantify the statistical correlations between some fundamental parameters that characterize the X-ray emission, i.e. the X-ray spectral slope, Γ, and the X-ray "loudness", and the accretion rate, both absolute (Ṁ ) and normalized to the Eddington luminosity (Eddington ratio, λ). We parametrize the Xray loudness using three different quantities: the bolometric correction, K bol , the twopoint spectral index α OX and the disk/corona luminosity ratio. We find that the X-ray spectral index depends on the normalized accretion rate while the "X-ray loudness" depends on both the normalized and the absolute accretion rate. The dependence on the Eddington ratio, in particular, is probably induced by the Γ − λ correlation. The two proxies usually adopted in the literature to quantify the X-ray loudness of an AGN, i.e. K bol and α OX , behave differently, with K bol being more sensitive to the Eddington ratio and α OX having a stronger dependence with the absolute accretion. The explanation of this result is likely related to the different sensitivity of the two parameters to the X-ray spectral index.