The Mg ii absorption line systems in quasar spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope

Abstract

Making use of quasar spectra from LAMOST, in the spectral data around the Mg ii emission lines, research described in this paper has detected 217 Mg ii narrow absorption lines (NALs) with W r λ 2796 ≥ 3 σ w and W r λ 2803 ≥ 2 σ w in a redshift range of 0.4554 ≤ z abs ≤ 2.1110. For quasars observed by both LAMOST and SDSS, we find that 135 Mg ii NALs were obviously observed in the LAMOST spectra, 347 Mg ii NALs were were apparent in the SDSS spectra, and 132 Mg ii NALs were clearly present in both the SDSS and LAMOST spectra. The missed Mg ii NALs are likely ascribed to low signal-to-noise ratios of corresponding spectra. Among the Mg ii NALs obviously observed in SDSS or LAMOST spectra, eight Mg ii NALs were significantly changed with | Δ W r λ 2796 | ≥ 3 σ w in time intervals of Δ MJD/(1 + z em) = 359 – 2819 d.

An Initial Analysis of a Strongly Lensed QSO Candidate Identified by LAMOST

“…From the "Unknown" data set in LAMOST DR7, Lu et al (2022) identified 106 new emission line galaxies and 29 new galactic H II regions. Chen et al (2021) penetrated into the Mg II absorption line systems in QSO spectra from LAMOST DR1-5. Chen et al (2023) derived an initial statistical analysis of LAMOST DR9 low resolution QSOs.…”