The MEXSAS2 Sample and the Ensemble X-ray Variability of Quasars

Frontiers in Astronomy and Space Sciences

Middei, Riccardo¹  Vagnetti, Fausto²  Serafinelli, Roberto³  Chiaraluce, Elia³ 

[1] di Roma Sapienza, Italy;di Roma Tor Vergata, Italy;Dipartimento di Fisica, Università

关键词: Catalogues;    quasars;    Spectral variability;    Structure function;    X-Rays;   

DOI  :  10.3389/fspas.2017.00021

学科分类：空间科学

来源: Frontiers

【 摘 要 】

We present the second Multi-Epoch X-ray Serendipitous AGN Sample (MEXSAS2), extracted from the 6th release of the XMM Serendipitous Source Catalogue release (XMMSSC-DR6), cross-matched with Sloan Digital Sky Survey quasar catalogues DR7Q and DR12Q. Our sample also includes the available measurements for masses, bolometric luminosities, and Eddington ratios. Analyses of the ensemble structure function and spectral variability are presented, together with their dependences on such parameters. We confirm a decrease of the structure function with the X-ray luminosity, and find a weak dependence on the black hole mass. We introduce a new spectral variability estimator, taking errors on both fluxes and spectral indices into account. We confirm an ensemble softer when brighter trend, with no dependence of such estimator on black hole mass, Eddington ratio, redshift, X-ray and bolometric luminosity.

【 授权许可】

CC BY