The Physical Relation between Disc and Coronal Emission in Quasars

Frontiers in Astronomy and Space Sciences

Lusso, Elisabeta²  Risaliti, Guido³ 

[1] di Firenze, Italy;Centre for Extragalactic Astronomy, Durham University, United Kingdom;Dipartimento di Fisica e Astronomia, Università

关键词: Active Galactic Nuclei (AGN);    Quasars: supermassive black holes;    accretion disk;    X-Rays;    Galaxies:active;   

DOI  :  10.3389/fspas.2017.00066

学科分类：空间科学

来源: Frontiers

【 摘 要 】

We propose a modified version of the observed non-linear relation between the X-ray (2 keV) and the ultraviolet (2500 Å) emission in quasars (i.e. LX ∝ LUV^γ ) which involves the full width at half-maximum, FWHM, of the broad emission line, i.e. LX ∝ L_UV^γ FWHM^β. By analysing a sample of 550 optically selected non-jetted quasars in the redshift range of 0.36–2.23 from the Sloan Digital Sky Survey cross matched with the XMM-Newton catalogue 3XMM-DR6, we found that the additional dependence of the observed LX − LUV correlation on the FWHM of the MgII broad emission line is statistically significant. Our statistical analysis leads to a much tighter relation with respect to the one neglecting FWHM, and it does not evolve with redshift. We interpret this new relation within an accretion disc corona scenario where reconnection and magnetic loops above the accretion disc can account for the production of the primary X-ray radiation. For a broad line region size depending on the disc luminosity as R_blr ∝ L^0.5 , we find that L_X ∝ L_UV^4/7 FWHM^4/7, which is in very good agreement with the observed correlation.

【 授权许可】

CC BY