PG 1254+047: An Intrinsically X-ray Weak, Heavily Absorbed BALQSO?

Abstract

We present \textit{Chandra} observations of the radio-quiet Broad Absorption Line (BAL) QSO PG 1254+047. We find that it is a weak X-ray source, with a total of $44\pm 7$ photons measured in 36 ksec across the observed energy range $0.7 - 6.0$ keV. Its X-ray weakness is consistent with the known correlation between $α_{ox}$ and the strength of the UV absorption lines. The spectral energy distribution suggests that PG 1254+047 is intrinsically X-ray weak, in addition to being heavily X-ray absorbed. The X-ray absorption column density is $N_{H} > 10^{23}$ cm$^{-2}$ for neutral gas, while the intrinsic (unabsorbed) emission spectrum has $α_{ox} > 2$. The data are fit best by including an ionized (rather than neutral) absorber, with column density $N_{H} \gtrsim 2\times 10^{23}$ cm$^{-2}$. The degree of ionization is consistent with the UV BALs, as is the total column density if the strongest UV lines are saturated. If the X-ray absorber forms in a wind that is radiatively accelerated to the BAL velocities, then the wind must be launched from a radius of about $10^{16}$ cm with a mass loss rate of $\sim 1$ M$_\odot$ yr$^{-1}$.