2018/10/29 by Yang, Jinyi, Wang, Feige, Fan, Xiaohui +10 · 1 citation
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.1810.11927
We present the final results from our survey of luminous z ∼ 5.5 quasars. This is the first systematic quasar survey focusing on quasars at z ∼ 5.5, during the post-reionization epoch. It has been challenging to select quasars at 5.3 < z < 5.7 using conventional color selections, due to their similar optical colors to those of late-type stars, especially M dwarfs. We developed a new selection technique for z ∼ 5.5 quasars based on optical, near-IR, and mid-IR photometry, using data from the Sloan Digital Sky Survey (SDSS), PanSTARR1 (PS1), the UKIRT Infrared Deep Sky Surveys - Large Area Survey, the UKIRT Hemisphere Survey, the VISTA Hemisphere Survey, and the Wide Field Infrared Survey Explorer (WISE), covering ∼ 11000 deg2 of high galactic latitude sky. In this paper, we present the discovery of 15 new quasars at z∼ 5.5. Together with results from Yang et al. (2017), our survey provides a complete, flux-limited sample of 31 quasars at 5.3 ≤ z ≤ 5.7. We measure the quasar spatial density at z ∼ 5.5 and M1450 < -26.2. Our result is consistent with the rapid decline of quasar spatial density from z = 5 to 6, with k=-0.66 ± 0.05 (ρ(z) ∝ 10kz). In addition, we present a new survey using optical colors only from the full PS1 area for luminous quasars at z = 5.0 - 5.5, beyond the SDSS footprint, and report the preliminary results from this survey, including 51 new quasars discovered at 4.61≤ z ≤5.71.