2011/03/10 by Peng Jiang, Jian Ge, Hongyan Zhou +2 · 3 citations
Physics and Astronomy · #Absorption (acoustics) #Astronomy and Astrophysical Research #Equivalent width #Extinction (optical mineralogy) #Galaxies: Formation, Evolution, Phenomena #Milky Way #Quasar #Redshift #Sky #Spectral line #Spectrograph #Stellar, planetary, and galactic studies #astro-ph.CO
paper · pdf · doi:10.1088/0004-637x/732/2/110
71 pages, 6 tables, 49 figures, accepted by ApJ, Table 1 is available entirely at http://home.ustc.edu.cn/~jpaty/dataset/qso_dr7.dat ;Table 2 is available entirely at http://home.ustc.edu.cn/~jpaty/dataset/rejected.list
arxiv created 2011/03/10 · openalex publication_date 2011/04/25 · arxiv updated 2015/05/27 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We report detections of 39 2175 Å dust extinction bump candidates associated with strong Mg ii absorption lines at z ∼ 1–1.8 on quasar spectra in Sloan Digital Sky Survey (SDSS) DR3. These strong Mg ii absorption line systems are detected among 2951 strong Mg ii absorbers with a rest equivalent width W r λ2796> 1.0 Å at 1.0 < z < 1.86, which is part of a full sample of 7421 strong Mg ii absorbers compiled by Prochter et al. The redshift range of the absorbers is chosen to allow the 2175 Å extinction features to be completely covered within the SDSS spectrograph operation wavelength range. An upper limit of the background quasar emission redshift at z = 2.1 is set to prevent the Lyα forest lines from contaminating the sensitive spectral region for the 2175 Å bump measurements. The FM90 parameterization is applied to model the optical/UV extinction curve in the rest frame of Mg ii absorbers of the 2175 Å bump candidates. The simulation technique developed by Jiang et al. is used to derive the statistical significance of the candidate 2175 Å bumps. A total of 12 absorbers are detected with 2175 Å bumps at a 5σ level of statistical significance, 10 are detected at a 4σ level, and 17 are detected at a 3σ level. Most of the candidate bumps in this work are similar to the relatively weak 2175 Å bumps observed in the Large Magellanic Cloud LMC2 supershell rather than the strong ones observed in the Milky Way. This sample has greatly increased the total number of 2175 Å extinction bumps measured on SDSS quasar spectra. Follow-up observations may rule out some of the possible false detections and reveal the physical and chemical natures of 2175 Å quasar absorbers.