Аннотация
We present $Chandra$ observations of seven broad absorption line (BAL)
quasars at $z=0.863$-2.516 with redshifted BAL troughs (RSBALs). Five of our
seven targets were detected by $Chandra$ in 4-13 ks exposures with ACIS-S. The
$\alpha_ox$ values, $\Delta\alpha_ox$ values, and spectral energy
distributions of our targets demonstrate they are all X-ray weak relative to
expectations for non-BAL quasars, and the degree of X-ray weakness is
consistent with that of appropriately-matched BAL quasars generally.
Furthermore, our five detected targets show evidence for hard X-ray spectral
shapes with a stacked effective power-law photon index of $\Gamma_\rm
eff=0.5^+0.5_-0.4$. These findings support the presence of heavy X-ray
absorption ($N_H2 10^23$ cm$^-2$) in RSBAL quasars,
likely by the shielding gas found to be common in BAL quasars more generally.
We use these X-ray measurements to assess models for the nature of RSBAL
quasars, finding that a rotationally-dominated outflow model is favored while
an infall model also remains plausible with some stipulations. The X-ray data
disfavor a binary quasar model for RSBAL quasars in general.
Пользователи данного ресурса
Пожалуйста,
войдите в систему, чтобы принять участие в дискуссии (добавить собственные рецензию, или комментарий)