A Metal-Strong and Dust-Rich Damped \lya Absorption System toward the Quasar SDSS J115705.52+615521.7

Abstract

(Abridged for arXiv) We report the discovery of an unusual, extremely dust-rich and metal-strong damped \lya absorption system (DLA) at a redshift $z_a=2.4596$ toward the quasar SDSS J115705.52+615521.7 (hereafter J1157+6155) with an emission-line redshift $z_e=2.5125$. Its neutral hydrogen column density $N_{\hi} = 10^{21.8\pm0.2}$ cm${}^{-2}$ is among the highest values measured in quasar DLAs. The measured metal column density is $N_{ZnII}\approx 10^{13.8}$ cm${}^{-2}$, which is about 1.5 times larger than the largest value in any previously observed quasar DLAs. The best-fit curve is a MW-like law with a significant broad feature centered around 2175 Å in the rest frame of the absorber. The measured extinction $A_V\approx 0.92$ mag is unprecedentedly high in quasar DLAs. After applying an extinction correction, the $i$ band absolute magnitude of the quasar is as high as $M_i\approx -29.4$ mag, placing it one of the most luminous quasars ever known. This discovery is suggestive of the existence of a rare yet important population of dust-rich DLAs with both high metallicities and high column densities, which may have significant impact on the measurement of the cosmic evolution of neutral gas mass density and metallicity.

15 pages, 10 figures, 1 table

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Cited by in corpus (8)

• Optical/near-infrared selection of red QSOs: Evidence for steep extinction curves towards galactic centers?
• A Comprehensive Study of Broad Absorption Line Quasars: I. Prevalence of HeI* Absorption Line Multiplets in Low-Ionization Objects
• The High A(V) Quasar Survey: Reddened quasi-stellar objects selected from optical/near-infrared photometry - II
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• The high A_V Quasar Survey: A z=2.027 metal-rich damped Lyman-alpha absorber towards a red quasar at z=3.21
• Quasar 2175 Å dust absorbers II: Correlation analysis and relationship with other absorption line systems
• Seven broad absorption line quasars with excess broad band absorption near 2250 Å
• The 2175 Å~ Bump Features in FeLoBAL Quasars: One Indicator of MW-like Dust in the Nuclear Region of Quasar