Host Dark Matter Halos of SDSS Red and Blue Quasars: No Significant Difference in Large-scale Environment

• Published in: The Astrophysical journal 2022-03, Vol.927 (1), p.16
• Main Authors: Petter, Grayson C., Hickox, Ryan C., Alexander, David M., Geach, James E., Myers, Adam D., Rosario, David J., Fawcett, Victoria A., Klindt, Lizelke, Whalen, Kelly E.
• Format: Article
• Language: English
• Subjects: Active galactic nuclei; Astronomy & Astrophysics; ASTRONOMY AND ASTROPHYSICS; Astrophysical black holes; Clustering; Cosmic microwave background radiation; Gravitational lensing; High-luminosity active galactic nuclei; Large-scale structure of the universe; Quasars; Radio active galactic nuclei; Radio quiet quasars; Two-point correlation function; Weak gravitational lensing
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ac4d31

The observed optical colors of quasars are generally interpreted in one of two frameworks: unified models that attribute the color to the random orientation of the accretion disk along the line of sight, and evolutionary models that invoke connections between quasar systems and their environments. We test these schemas by probing the dark matter halo environments of optically selected quasars as a function of g − i optical color by measuring the two-point correlation functions of ∼0.34 million eBOSS quasars as well as the gravitational deflection of cosmic microwave background photons around ∼0.66 million XDQSO photometric quasar candidates. We do not detect a trend of halo bias with optical color through either analysis, finding that optically selected quasars at 0.8 < z < 2.2 occupy halos of characteristic mass M h ∼ 3 × 10 12 h −1 M ⊙ regardless of their color. This result implies that a quasar’s large-scale halo environment is not strongly connected to its observed optical color. We also confirm the findings of fundamental differences in the radio properties of red and blue quasars by stacking 1.4 GHz FIRST images at their positions, suggesting the observed differences cannot be attributed to orientation. Instead, the differences between red and blue quasars likely arise on nuclear-galactic scales, perhaps owing to reddening by a nuclear dusty wind. Finally, we show that optically selected quasars’ halo environments are also independent of their r − W2 optical–infrared colors, while previous work has suggested that mid-infrared-selected obscured quasars occupy more massive halos. We discuss the implications of this result for models of quasar and galaxy coevolution.