Research Division Seminar
A new black-hole mass scaling relation based on coronal gas emission and its dependance with the accretion disc

Abstract

Insights on the shape and nature of the ionizing continuum in astronomical objects are usually inferred via indirect methods as high energy photons are absorbed by our Galaxy. This talk will discuss the relevance of high ionization-potential coronal lines as unique tracers on the ionizing continuum  of active galactic nuclei (AGN), and of active black-hole in general.Focussing on AGN,  using bona-fide black-hole  masses from reverberation mapping and the strong infrared coronal line [Si vi] 1.96 um, a novel BH-mass scaling relation of the form log(M_BH) = (6.40 ± 0.17) − (1.99 ± 0.37)× log ([Si vi] / Brγ_broad) over  the BH mass interval, 10^6 − 10^8 Mo, is found. The dispersion of the relation is 0.47 dex, comparable with that of the canonical "M-sigma" relation.   Following on the thinaccretion disc approximation and after surveying a basic parameter space for coronal lines production, we believe a main driver of the relation is the effective temperature of the disc, which is effectively sampled by the [Si vi] 1.96 um coronal line. By means of CLOUDY photoionisation models, the observed anti-correlation appears formally in line with the thin disc prediction Tdisc prop M_BH^(-1/4).

Zoom:

https://rediris.zoom.us/j/5614942498
Meeting ID: 561 494 2498

YouTube:

https://youtu.be/lfYhJ0pMwTY