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The Chandra view of the Lx-Luv relation in quasars and a hint to its outliers

Presentation #404.02 in the session The Chandra Source Catalog version 2.1: New Avenues for Discovery in X-ray Datasets.

Published onJul 01, 2023
The Chandra view of the Lx-Luv relation in quasars and a hint to its outliers

The relation between X-ray and UV luminosities in quasars, holding for several decades in both bands and over a wide redshift range, suggests that the physical mechanism regulating the energy transfer from the accretion disc to the hot corona must be universal. For the first time, we used X-ray spectroscopic data from the Chandra Source Catalog 2.0 for a sample of >2000 SDSS DR14 quasars, finding a smaller intrinsic dispersion in the Lx-Luv relation at high redshift (delta < 0.2 dex) with respect to studies that used photometric data from catalogs and confirming its non-evolution up to z~4.5. However, the Lx-Luv relation can also be used to delve into the physics of accretion, by identifying the “outsiders”, sources which show a different state of the accretion disc/hot corona system with respect to the average population. An example are X-ray-weak quasars, whose weakness is ascribable to a radiatively inefficient state of the corona and whose optical properties hint to the presence of a powerful accretion disc wind.The combination of the statistics and the spectroscopic information available in the CSC2.0/SDSS sample paves the way for a deeper investigation of the central engine in AGN.

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