SDSS J013127.34$-$032100.1: A newly discovered radio-loud quasar at $z=5.18$ with extremely high luminosity

TL;DR

This paper reports the discovery of a highly luminous, radio-loud quasar at redshift 5.18, with an exceptionally high bolometric luminosity and massive black hole, expanding understanding of early universe quasars.

Contribution

First discovery of a radio-loud quasar at z>5 with extremely high luminosity and black hole mass, providing new insights into early supermassive black hole growth.

Findings

Redshift of 5.18 for the quasar.

Bolometric luminosity approximately 1.1E48 erg/s.

Black hole mass estimated at 2.7E9 solar masses.

Abstract

Only very few z>5 quasars discovered to date are radio-loud, with a radio-to-optical flux ratio (radio-loudness parameter) higher than 10. Here we report the discovery of an optically luminous radio-loud quasar, SDSS J013127.34-032100.1 (J0131-0321 in short), at z=5.18+-0.01 using the Lijiang 2.4m and Magellan telescopes. J0131-0321 has a spectral energy distribution consistent with that of radio-loud quasars. With an i-band magnitude of 18.47 and radio flux density of 33 mJy, its radio-loudness parameter is ~100. The optical and near-infrared spectra taken by Magellan enable us to estimate its bolometric luminosity to be L_bol ~ 1.1E48 erg/s, approximately 4.5 times greater than that of the most distant quasar known to date. The black hole mass of J0131-0321 is estimated to be 2.7E9 solar masses, with an uncertainty up to 0.4 dex. Detailed physical properties of this high-redshift, radio-loud, potentially super-Eddington quasar can be probed in the future with more dedicated and intensive follow-up observations using multi-wavelength facilities.