SDSS J013127.34-032100.1: a candidate blazar with a 11 billion solar mass black hole at $z$=5.18

TL;DR

This paper reports the discovery and analysis of a high-redshift, radio-loud quasar with an exceptionally massive black hole, providing insights into early black hole growth and jet orientation in the universe.

Contribution

It presents the identification and detailed spectral analysis of a candidate blazar at z=5.18 with the largest known black hole mass at that redshift among radio-loud objects.

Findings

Black hole mass estimated at (1.1+-0.2)×10^10 solar masses

Viewing angle between 3 and 5 degrees

Implications for the existence of many similar sources with jets pointing away from Earth

Abstract

The radio-loud quasar SDSS J013127.34-032100.1at a redshift z=5.18 is one of the most distant radio-loud objects. The radio to optical flux ratio (i.e. the radio-loudness) of the source is large, making it a promising blazar candidate. Its overall spectral energy distribution, completed by the X-ray flux and spectral slope derived through Target of Opportunity Swift/XRT observations, is interpreted by a non-thermal jet plus an accretion disc and molecular torus model. We estimate that its black hole mass is (1.1+-0.2)1e10 Msun. for an accretion efficiency eta=0.08, scaling roughly linearly with eta. Although there is a factor ~2 of systematic uncertainty, this black hole mass is the largest found at these redshifts in a radio loud object. We derive a viewing angle between 3 and 5 degrees. This implies that there must be other (hundreds) sources with the same black hole mass of SDSS J013127.34-032100.1, but whose jets are pointing away from Earth. We discuss the problems posed by the existence of such large black hole masses at such redshifts, especially in jetted quasars. In fact, if they are associated to rapidly spinning black holes, the accretion efficiency is high, implying a slower pace of black hole growth with respect to radio-quiet quasars.