From near-infrared spectroscopic measurements of the Mg II emission line doublet, we estimate the black hole (BH) mass of the quasar, SMSS J215728.21-360215.1, as being (3.4 ± 0.6) × 1010 M⊙ and refine the redshift of the quasar to be z = 4.692. SMSS J2157 is the most luminous known quasar, with a 3000 Å luminosity of (4.7 ± 0.5) × 1047 erg s-1 and an estimated bolometric luminosity of 1.6 × 1048 erg s-1, yet its Eddington ratio is only ∼0.4. Thus, the high luminosity of this quasar is a consequence of its extremely large BH - one of the most massive BHs at z > 4.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2020
- galaxies: active;
- quasars: individual: SMSS J215728.21–360215.1;
- Astrophysics - Astrophysics of Galaxies
- 7 pages, 3 figures. Accepted for publication in MNRAS