The Most Distant Radio Loud Quasar

quasar_radio_emission.pngPowerful radio jets from supermassive black holes (SMBHs) have a profound influence on their local environments, regulating star formation in the host galaxy and polluting the intergalactic medium with atoms and magnetic fields. They may also facilitate the formation of SMBH by removing angular momentum from the accretion disk.  However, finding radio Active Galactic Nuclei in the early Universe has proven difficult.

Radio sources at the highest redshifts provide unique information on the first massive galaxies and black holes, the densest primordial environments, and the epoch of reionization. The number of astronomical objects identified at z > 6 has increased dramatically over the last few years, but previously only three radio-loud sources have been reported at z >6 , the most distant being a quasar at z = 6.18.

These two contributions–from the Jansky Very Large Array (VLA: Bañados et al.) and the Very Long Baseline Array (VLBA: Momjiam et al.)–report the discovery and characterization of the most distant radio-loud Active Galactic Nucleus to date, at z = 6.82, or just ~800 Myr after the Big Bang. This source has a black hole mass of ~ 3 x 108 M⊙ and is one of the fastest accreting quasars. The VLBA imaging implies a marginally resolved source, with a size ≤ 10 milli-arcseconds, or ~ 50 parsecs. The small size, but steep radio spectrum at high frequency, implies a very young radio jet, with an estimated age of only ~ 2000 years.

Figure caption: [Left] VLBA 1.4 GHz image of the z = 6.8 radio loud quasar. [Right] A compilation of all the z > 5 radio loud AGN known (Banados et al. 2021; Momjian et al. 2021).

Publication-1: Eduardo Bañados (Max Planck Institute for Astronomy, Carnegie Institution of Washington) et al., The Discovery of a Highly Accreting, Radio-loud Quasar at z=6.82, Astrophysical Journal  909, 80 (1 March 2021).

Publication-2: Emmanuel Momjiam (NRAO) et al., Resolving the Radio Emission from the Quasar P172+18 at z = 6.82, Astronomical Journal, 161, 207 (1 May 2021).

NRAO Press Release: Most Distant Cosmic Jet Providing Clues About Early Universe

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