* Astronomy

Title: SDSS J013127.34-032100.1: a candidate blazar with a 11 billion solar mass black hole at z=5.18
Author: G. Ghisellini (1), G. Tagliaferri (1), T. Sbarrato (1,2), N. Gehrels (3) ((1) INAF -- Brera Obs., (2) Univ. Milano-Bicocca (3) Goddard)

The radio-loud quasar SDSS J013127.34-032100.1 at 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 slope derived through Target of Opportunity Swift/XRT observations, is interpreted by a jet non-thermal plus an accretion disc and molecular torus model. We estimate that its black hole mass is (1.1±0.2)e10 Msun, the largest found at these redshifts. 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.

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