English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present deeper Chandra observations for weak-line quasars (WLQs) in arepresentative sample that previously had limited X-ray constraints, andperform X-ray photometric analyses to reveal the full range of X-ray propertiesof WLQs. Only 5 of the 32 WLQs included in this representative sample remainX-ray undetected after these observations, and a stacking analysis shows thatthese 5 have an average X-ray weakness factor of > 85. One of the WLQs in thesample that was known to have extreme X-ray variability, SDSS J1539+3954,exhibited dramatic X-ray variability again: it changed from an X-ray normalstate to an X-ray weak state within ~ 3 months in the rest frame. This shorttimescale for an X-ray flux variation by a factor of $\gtrsim$ 9 furthersupports the thick disk and outflow (TDO) model proposed to explain the X-rayand multiwavelength properties of WLQs. The overall distribution of theX-ray-to-optical properties of WLQs suggests that the TDO has an averagecovering factor of the X-ray emitting region of ~ 0.5, and the column densityof the TDO can range from $N_{\rm H}$ $\sim 10^{23-24}~{\rm cm}^{-2}$ to$N_{\rm H}$ $\gtrsim 10^{24}~{\rm cm}^{-2}$, which leads to different levels ofabsorption and Compton reflection (and/or scattering) among WLQs.

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