| Title | Constraining the Quasar Radio-loud Fraction at z similar to 6 with Deep Radio Observations |
| Authors | Liu, Yuanqi Wang, Ran Momjian, Emmanuel Banados, Eduardo Zeimann, Greg Willott, Chris J. Matsuoka, Yoshiki Omont, Alain Shao, Yali Li, Qiong Li, Jianan |
| Affiliation | Peking Univ Beijing, Kavli Inst Astron & Astrophys, Beijing, Peoples R China Peking Univ Beijing, Sch Phys, Dept Astron, Beijing, Peoples R China Natl Radio Astron Observ, POB O, Socorro, NM 87801 USA Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany Univ Texas Austin, Hobby Eberly Telescope, Austin, TX 78712 USA NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada Ehime Univ, Res Ctr Space & Cosm Evolut, Matsuyama, Ehime 7908577, Japan Sorbonne Univ, Inst Astrophys Paris, CNRS, UMR 7095, 98 Bis Bd Arago, F-75014 Paris, France Max Planck Inst Radioastron, Hugel 69, D-53121 Bonn, Germany |
| Issue Date | Feb-2021 |
| Publisher | ASTROPHYSICAL JOURNAL |
| Abstract | We carry out a series of deep Karl G. Jansky Very Large Array (VLA) S-band observations of a sample of 21 quasars at z similar to 6. The new observations expand the searches of radio continuum emission to the optically faint quasar population at the highest redshift with rest-frame A luminosities down to 3 x 10(11) L-circle dot. We report the detections of two new radio-loud quasars: CFHQS J2242+0334 (hereafter J2242+0334) at z = 5.88 and CFHQS J0227-0605 (hereafter J0227-0605) at z = 6.20, detected with 3 GHz flux densities of 87.0 +/- 6.3 mu Jy and 55.4 +/- 6.7 mu Jy, respectively. Their radio loudnesses are estimated to be 54.9 +/- 4.7 and 16.5 +/- 3.2, respectively. To better constrain the radio-loud fraction (RLF), we combine the new measurements with the archival VLA L-band data as well as available data from the literature, considering the upper limits for non-detections and possible selection effects. The final derived RLF is 9.4 +/- 5.7% for the optically selected quasars at z similar to 6. We also compare the RLF to that of the quasar samples at low redshift and check the RLF in different quasar luminosity bins. The RLF for the optically faint objects is still poorly constrained due to the limited sample size. Our results show no evidence of significant quasar RLF evolution with redshift. There is also no clear trend of RLF evolution with quasar UV/optical luminosity due to the limited sample size of optically faint objects with deep radio observations. |
| URI | http://hdl.handle.net/20.500.11897/605047 |
| ISSN | 0004-637X |
| DOI | 10.3847/1538-4357/abd3a8 |
| Indexed | SCI(E) |
| Appears in Collections: | 科维理天文与天体物理研究所 物理学院 |
