Rest-Frame Optical Spectroscopy of Ten z $\sim$ 2 Weak Emission-Line Quasars
| Autor: | Chen, Ying, Luo, Bin, Brandt, W. N., Zuo, Wenwen, Dix, Cooper, Ha, Trung, Matthews, Brandon, Paul, Jeremiah D., Plotkin, Richard M., Shemmer, Ohad |
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| Rok vydání: | 2024 |
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| Druh dokumentu: | Working Paper |
| Popis: | We present near-infrared spectroscopy of ten weak emission-line quasars (WLQs) at redshifts of $z\sim2$, obtained with the Palomar 200-inch Hale Telescope. WLQs are an exceptional population of type 1 quasars that exhibit weak or no broad emission lines in the ultraviolet (e.g., the C IV $\lambda 1549$ line), and they display remarkable X-ray properties. We derive H$\beta$-based single-epoch virial black-hole masses (median value $\rm 1.7 \times 10^{9} M_{\odot}$) and Eddington ratios (median value $0.5)$ for our sources. We confirm the previous finding that WLQ H$\beta$ lines, as a major low-ionization line, are not significantly weak compared to typical quasars. The most prominent feature of the WLQ optical spectra is the universally weak/absent [O III] $\lambda 5007$ emission. They also display stronger optical Fe II emission than typical quasars. Our results favor the super-Eddington accretion scenario for WLQs, where the weak lines are a result of a soft ionizing continuum; the geometrically thick inner accretion disk and/or its associated outflow is responsible for obscuring the nuclear high-energy radiation and producing the soft ionizing continuum. We also report candidate extreme [O III] outflows (blueshifts of $\approx 500$ and $\rm 4900 km s^{-1}$) in one object. Comment: 19 pages, 8 figures, accepted for publication in ApJ |
| Databáze: | arXiv |
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