| Title | Metallicity in Quasar Broad-line Regions at Redshift similar to 6 |
| Authors | Wang, Shu Jiang, Linhua Shen, Yue Ho, Luis C. Vestergaard, Marianne Banados, Eduardo Willott, Chris J. Wu, Jin Zou, Siwei Yang, Jinyi Wang, Feige Fan, Xiaohui Wu, Xue-Bing |
| Affiliation | Peking Univ, Kavli Inst Astron & Astrophys, Beijing 100871, Peoples R China Seoul Natl Univ, Dept Phys & Astron, Astron Program, Seoul 08826, South Korea Peking Univ, Sch Phys, Dept Astron, Beijing 100871, Peoples R China Univ Illinois, Dept Astron, Urbana, IL 61801 USA Univ Illinois, Natl Ctr Supercomp Applicat, Urbana, IL 61801 USA Univ Arizona, Steward Observ, 933 North Cherry Ave, Tucson, AZ 85721 USA Univ Copenhagen, Niels Bohr Inst, Juliane Manes Vej 30, DK-2100 Copenhagen, Denmark Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada |
| Keywords | NEAR-INFRARED SPECTROSCOPY DIGITAL SKY SURVEY BLACK-HOLE MASSES DELAY-TIME DISTRIBUTION ACTIVE GALACTIC NUCLEI EMISSION-LINE IA SUPERNOVAE MG II CHEMICAL EVOLUTION ELEMENTAL ABUNDANCES |
| Issue Date | 1-Feb-2022 |
| Publisher | ASTROPHYSICAL JOURNAL |
| Abstract | Broad-line regions (BLRs) in high-redshift quasars provide crucial information on chemical enrichment in the early universe. Here we present a study of BLR metallicities in 33 quasars at redshift 5.7 < z < 6.4. Using the near-IR spectra of the quasars obtained from the Gemini telescope, we measure their rest-frame UV emission-line flux and calculate flux ratios. We then estimate BLR metallicities with empirical calibrations based on photoionization models. The inferred median metallicity of our sample is a few times the solar value, indicating that the BLR gas had been highly metal enriched at z similar to 6. We compare our sample with a low-redshift quasar sample with similar luminosities and find no evidence of redshift evolution in quasar BLR metallicities. This is consistent with previous studies. The Fe ii/Mg ii flux ratio, a proxy for the Fe/alpha element abundance ratio, shows no redshift evolution as well, further supporting rapid nuclear star formation at z similar to 6. We also find that the black hole mass-BLR metallicity relation at z similar to 6 is consistent with the relation measured at 2 < z < 5, suggesting that our results are not biased by a selection effect due to this relation. |
| URI | http://hdl.handle.net/20.500.11897/637513 |
| ISSN | 0004-637X |
| DOI | 10.3847/1538-4357/ac3a69 |
| Indexed | SCI(E) |
| Appears in Collections: | 科维理天文与天体物理研究所 物理学院 |
