Discovery of the most luminous quasar of the last 9 Gyr
Abstract
We report the discovery of a bright ( g = 14.5 mag (AB), K = 11.9 mag (Vega)) quasar at redshift z=0.83 — the optically brightest (unbeamed) quasar at z>0.4. SMSS J114447.77-430859.3, at a Galactic latitude of b=+18.1°, was identified by its optical colours from the SkyMapper Southern Survey (SMSS) during a search for symbiotic binary stars. Optical and near-infrared spectroscopy reveals broad Mg II, H β, H α, and Pa β emission lines, from which we measure a black hole mass of log10 (MBH/M⊙) = 9.4 plusmn; 0.5. With its high luminosity, Lbol = (4.7±1.0)×1047 erg s-1 or Mi(z=2) = -29.74 mag (AB), we estimate an Eddington ratio of ≈1.4. As the most luminous quasar known over the last ∼ 9 Gyr of cosmic history, having a luminosity 8× greater than 3C 273, the source offers a range of potential follow-up opportunities.
- Publication:
-
Publications of the Astronomical Society of Australia
- Pub Date:
- 2022
- DOI:
- 10.1017/pasa.2022.36
- arXiv:
- arXiv:2206.04204
- Bibcode:
- 2022PASA...39...37O
- Keywords:
-
- active galactic nuclei: quasars;
- supermassive black holes;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 13 pages. Accepted for publication in PASA