2012/06/30 by Cristian E. Rusu, Masamune Oguri, Masanori Iye +5
Engineering · Physics and Astronomy · #Astronomy and Astrophysical Research #Dark matter #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Gravitational lens #Gravitational microlensing #Halo #Quasar #Redshift #Space Technology and Applications #Velocity dispersion #Virial mass #astro-ph.CO
paper · pdf · doi:10.1088/0004-637x/765/2/139
published as ApJ, 765, 139 (2013) · Published in The Astrophysical Journal
openalex publication_date 2013/02/27 · arxiv created 2013/03/01 · arxiv updated 2015/06/05 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report the discovery of a pair of quasars at z = 1.487, with a separation of 8 585 ± 0 002. Subaru Telescope infrared imaging reveals the presence of an elliptical and a disk-like galaxy located almost symmetrically between the quasars, in a cross-like configuration. Based on absorption lines in the quasar spectra and the colors of the galaxies, we estimate that both galaxies are located at redshift z = 0.899. This, as well as the similarity of the quasar spectra, suggests that the system is a single quasar multiply imaged by a galaxy group or cluster acting as a gravitational lens, although the possibility of a binary quasar cannot be fully excluded. We show that the gravitational lensing hypothesis implies that these galaxies are not isolated, but must be embedded in a dark matter halo of virial mass ∼4 × 10 14 h −1 70 M ☉ assuming a Navarro–Frenk–White model with a concentration parameter of c vir = 6, or a singular isothermal sphere profile with a velocity dispersion of ∼670 km s −1 . We place constraints on the location of the dark matter halo, as well as the velocity dispersions of the galaxies. In addition, we discuss the influence of differential reddening, microlensing, and intrinsic variability on the quasar spectra and broadband photometry.