影响因子：5.8
DOI码：10.3847/1538-4357/abd3a8
发表刊物：The Astrophysical Journal
摘要：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 ∼ 6. The new observations expand the searches of radio continuum emission to the optically faint quasar population at the highest redshift with rest-frame 4400A˚ luminosities down to 3×1011 L⊙ . 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 μJy and 55.4±6.7 μJy , 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 ∼ 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.
合写作者：Ran Wang, Emmanuel Momjian, Eduardo Bañados, Greg Zeimann, Chris J. Willott, Yoshiki Matsuoka, Alain Omont, Yali Shao, Qiong Li, and Jianan Li
第一作者：Yuanqi Liu
卷号：908
期号：2
页面范围：124
是否译文：否
发表时间：2021-02-18
收录刊物：SCI
发布期刊链接：https://iopscience.iop.org/article/10.3847/1538-4357/abd3a8