The blazar S5 0014+813: a real or apparent monster?

TL;DR

This study confirms the presence of an extremely massive black hole in the blazar S5 0014+813, with an estimated mass of 40 billion solar masses, based on multi-wavelength observations and spectral energy distribution analysis.

Contribution

It provides a detailed spectral energy distribution analysis confirming one of the largest black hole masses ever estimated in a blazar.

Findings

Black hole mass estimated at 40 billion solar masses.

Optical-UV emission consistent with a standard accretion disk.

Black hole radiates at 40% of the Eddington luminosity.

Abstract

A strong hard X-ray luminosity from a blazar flags the presence of a very powerful jet. If the jet power is in turn related to the mass accretion rate, the most luminous hard X-ray blazars should pinpoint the largest accretion rates, and therefore the largest black hole masses. These ideas are confirmed by the Swift satellite observations of the blazar S5 0014+813, at the redshift z=3.366. Swift detected this source with all its three instruments, from the optical to the hard X-rays. Through the construction of its spectral energy distribution we are confident that its optical-UV emission is thermal in origin. Associating it to the emission of a standard optically thick geometrically thin accretion disk, we find a black hole mass of 40 billion solar masses, radiating at 40% the Eddington value. The derived mass is among the largest ever found. Super-Eddington slim disks or thick disks with the presence of a collimating funnel can in principle reduce the black hole mass estimate, but tends to produce spectra bluer than observed.