Ultra-luminous quasars at redshift z > 4.5 from SkyMapper

Christian Wolf , Wei Jeat Hon , Fuyan Bian , Christopher A. Onken , Noura Alonzi , Michael A. Bessell , Zefeng Li , Brian P. Schmidt , Patrick Tisserand (1)

1 IAP - Institut d'Astrophysique de Paris

The most luminous quasars at high-redshift harbour the fastest growing and most massive black holes in the early Universe. They are exceedingly rare and hard to find. Here, we present our search for the most luminous quasars in the redshift range from z = 4.5 to 5 using data from SkyMapper, Gaia, and WISE. We use colours to select likely high-redshift quasars and reduce the stellar contamination of the candidate set with parallax and proper motion data. In ∼12 500 deg² of Southern sky, we find 92 candidates brighter than R_p = 18.2. Spectroscopic follow-up has revealed 21 quasars at z ≥ 4 (16 of which are within z = [4.5, 5]), as well as several red quasars, Broad-Absorption-Line (BAL) quasars and objects with unusual spectra, which we tentatively label OFeLoBALQSOs at redshifts of z ≈ 1 to 2. This work lifts the number of known bright z ≥ 4.5 quasars in the Southern hemisphere from 10 to 26 and brings the total number of quasars known at R_p < 18.2 and z ≥ 4.5 to 42.

Keywords: galaxies: active; quasars: general; early Universe; Astrophysics - Astrophysics of Galaxies

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]

Christian Wolf, Wei Jeat Hon, Fuyan Bian, Christopher A. Onken, Noura Alonzi, et al.. Ultra-luminous quasars at redshift z > 4.5 from SkyMapper. Monthly Notices of the Royal Astronomical Society, 2020, 491, pp.1970-1979. ⟨10.1093/mnras/stz2955⟩. ⟨insu-03748072⟩