Sensitive Chandra coverage of a representative sample of weak-line quasars: Revealing the full range of X-ray properties

Q. Ni, W. N. Brandt, B. Luo, G. P. Garmire, P. B. Hall, R. M. Plotkin, O. Shemmer, J. D. Timlin, F. Vito, J. Wu, W. Yi

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13 Scopus citations

Abstract

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 ≈3 months in the rest frame. This short time-scale for an X-ray flux variation by a factor of ≳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 ∼0.5, and the column density of the TDO can range from $N_rm H, sim 1023-24~rm cm-2$ to $N_rm H, gtrsim 1024~rm cm-2$, which leads to different levels of absorption and Compton reflection (and/or scattering) among WLQs.

Original languageEnglish (US)
Pages (from-to)5251-5264
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume511
Issue number4
DOIs
StatePublished - Apr 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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