The Unusual Absorption Line Spectrum of Quasar SDSS J2220+0109 |
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| Authors: | Ji Tuo Zhou Hong-yan Wang Ting-gui Wang Hui-yuan |
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| Institution: | 1. University of Science and Technology of China, Hefei 230026;2. Polar Research Institute of China, Shanghai 200136 |
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| Abstract: | We report the Balmer broad absorption lines (BALs) in the quasar SDSS J2220 + 0109 discovered from the SDSS data, and present a detailed analysis of the peculiar absorption line spectrum, including the He I* multiplet at λλ3189, 3889 arising from the metastable 23s-state helium and the Balmer Hα and Hβ lines from the excited hydrogen H I of n = 2 level, which are rarely seen in quasar spectra, as well as many absorption lines arising from the excited Fe II* of the levels 7 955 cm−1, 13 474 cm−1 and 13 673 cm−1 in the wavelength range 3100∼3300 Å. Ca II H, K absorption line doublets also clearly appear in the SDSS spectrum. All absorption lines show a similar blueshifted velocity structure of Δv ≈ − 1500 ∼ 0 km·s−1 relative to the quasar's systematic redshift determined from the emission lines. Detailed analysis suggests that the Balmer absorption lines should arise from the partially ionized region with a column density of NHI ≈ 1021 cm−2 for an electron density of ne ∼ 106 cm−3; and that the hydrogen n = 2 level may be populated via collisional excitation with Lyα pumping. |
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| Keywords: | Quasar: Absorption lines&mdash quasar: Emission lines&mdash quasar: Indi- vidual: SDSS J2220 + 0109 |
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