期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 511, 期 4, 页码 5251-5264出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stac394
关键词
galaxies: active; galaxies: nuclei; quasars: general; X-rays: galaxies
资金
- Chandra X-ray Center [GO0-21080X, DDO-21113X]
- NASA [80NSSC20K0795, NAS8-03060]
- National Natural Science Foundation of China [11991053]
- China Manned Space Project [CMS-CSST-2021-A05, CMS-CSST-2021-A06]
- UKRI Future Leaders Fellowship [MR/T020989/1]
- Huntingdon Institute [SV2-82024]
- Penn State ACIS Instrument Team by the Chandra X-ray Center [SV4-74018]
Deeper Chandra observations of weak-line quasars (WLQs) in a representative sample with previously limited X-ray constraints reveal diverse X-ray properties, with some showing extreme variability. The study supports the thick disc and outflow (TDO) model in explaining WLQs' X-ray and multiwavelength properties, with an average covering factor and a range of column densities leading to different levels of absorption and Compton reflection (and/or scattering) among WLQs.
We present deeper Chandra observations for weak-line quasars (WLQs) in a representative sample that previously had limited X-ray constraints, and perform X-ray photometric analyses to reveal the full range of X-ray properties of WLQs. Only 5 of the 32 WLQs included in this representative sample remain X-ray undetected after these observations, and a stacking analysis shows that these 5 have an average X-ray weakness factor of >85. One of the WLQs in the sample that was known to have extreme X-ray variability, SDSS J1539+3954, exhibited dramatic X-ray variability again: it changed from an X-ray normal state to an X-ray weak state within approximate to 3 months in the rest frame. This short time-scale for an X-ray flux variation by a factor of greater than or similar to 9 further supports the thick disc and outflow (TDO) model proposed to explain the X-ray and multiwavelength properties of WLQs. The overall distribution of the X-ray-to-optical properties of WLQs suggests that the TDO has an average covering factor of the X-ray emitting region of similar to 0.5, and the column density of the TDO can range from N-H similar to 10(23-24) cm(-2) to N-H greater than or similar to 10(24) cm(-2), which leads to different levels of absorption and Compton reflection (and/or scattering) among WLQs.
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