Discovery of Merging Twin Quasars at z = 6.05
Abstract
We report the discovery of two quasars at a redshift of z = 6.05 in the process of merging. They were serendipitously discovered from the deep multiband imaging data collected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program survey. The quasars, HSC J121503.42‑014858.7 (C1) and HSC J121503.55‑014859.3 (C2), both have luminous (>1043 erg s‑1) Lyα emission with a clear broad component (full width at half maximum >1000 km s‑1). The rest-frame ultraviolet (UV) absolute magnitudes are M 1450 = ‑ 23.106 ± 0.017 (C1) and ‑22.662 ± 0.024 (C2). Our crude estimates of the black hole masses provide $\mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })=8.1\pm 0.3$ in both sources. The two quasars are separated by 12 kpc in projected proper distance, bridged by a structure in the rest-UV light suggesting that they are undergoing a merger. This pair is one of the most distant merging quasars reported to date, providing crucial insight into galaxy and black hole build-up in the hierarchical structure formation scenario. A companion paper will present the gas and dust properties captured by Atacama Large Millimeter/submillimeter Array observations, which provide additional evidence for and detailed measurements of the merger, and also demonstrate that the two sources are not gravitationally lensed images of a single quasar.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2024
- DOI:
- 10.3847/2041-8213/ad35c7
- arXiv:
- arXiv:2405.02465
- Bibcode:
- 2024ApJ...965L...4M
- Keywords:
-
- Double quasars;
- Quasars;
- Reionization;
- High-redshift galaxies;
- Active galactic nuclei;
- Galaxy mergers;
- Supermassive black holes;
- 406;
- 1319;
- 1383;
- 734;
- 16;
- 608;
- 1663;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Published from ApJL. A companion paper (T. Izumi et al.) presents the associated ALMA observations