TY - JOUR
T1 - Sensitive Chandra coverage of a representative sample of weak-line quasars
T2 - Revealing the full range of X-ray properties
AU - Ni, Q.
AU - Brandt, W. N.
AU - Luo, B.
AU - Garmire, G. P.
AU - Hall, P. B.
AU - Plotkin, R. M.
AU - Shemmer, O.
AU - Timlin, J. D.
AU - Vito, F.
AU - Wu, J.
AU - Yi, W.
N1 - Publisher Copyright:
© 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2022/4/1
Y1 - 2022/4/1
N2 - 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.
AB - 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.
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U2 - 10.1093/mnras/stac394
DO - 10.1093/mnras/stac394
M3 - Article
AN - SCOPUS:85126737461
SN - 0035-8711
VL - 511
SP - 5251
EP - 5264
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -