2018/11/22 by Yongjung Kim, Myungshin Im, Yiseul Jeon +26 · 20 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Emissivity #Galaxies: Formation, Evolution, Phenomena #Galaxy #Infrared #Optics #Photometric redshift #Physics #Quasar #Redshift #Reionization #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aaf387
published in The Astrophysical Journal 870(2), 86 (IOP Publishing) · 24 pages, 9 figures, 6 tables. Accepted for publication in ApJ
arxiv created 2018/11/22 · openalex created_date 2018/11/29 · openalex publication_date 2019/01/10 · arxiv updated 2019/01/16 · openalex updated_date 2026/08/05
Abstract The faint quasars with M 1450 > −24 mag are known to hold the key to the determination of the ultraviolet emissivity for the cosmic reionization. But only a few have been identified so far because of the limitations on the survey data. Here we present the first results of the z ∼ 5 faint quasar survey with the Infrared Medium-deep Survey (IMS), which covers ∼100 deg 2 areas in J band to the depths of J AB ∼ 23 mag. To improve selection methods, the medium-band follow-up imaging has been carried out using the SED camera for QUasars in Early uNiverse (SQUEAN) on the Otto Struve 2.1 m Telescope. The optical spectra of the candidates were obtained with 8 m class telescopes. We newly discovered 10 quasars with −25 < M 1450 < −23 at z ∼ 5, among which three have been missed in a previous survey using the same optical data over the same area, implying the necessity for improvements in high-redshift faint quasar selection. We derived photometric redshifts from the medium-band data and found that they have high accuracies of . The medium-band-based approach allows us to rule out many of the interlopers that contaminate ≳20% of the broadband-selected quasar candidates. These results suggest that the medium-band-based approach is a powerful way to identify z ∼ 5 quasars and measure their redshifts at high accuracy (1%–2%). It is also a cost-effective way to understand the contribution of quasars to the cosmic reionization history.