XMM-NewtonandChandraSpectroscopy of the Variable High-Energy Absorption of PG 1115+080: Refined Outflow Constraints

We present results from multi-epoch spectral analysis of XMM-Newton andChandra observations of the mini broad absorption line (BAL) quasar PG1115+080. This is one of the few X-ray detected mini-BAL quasars to date thatis bright enough in the X-ray band, mostly due to large gravitational-lensingmagnifications, to allow in-depth spectral analysis. The present XMM-Newtonobservations of PG 1115+080 have provided the highest signal-to-noise X-rayspectra of a mini-BAL quasar obtained to date. By modeling the spectra of PG1115+080 we have obtained constraints on the column density and ionizationstate of its outflowing absorbing gas. A comparison between these constraintsover several epochs indicates significant variability in the properties of theoutflowing absorbers in PG 1115+080. The depths of the high-energy broadabsorption features in PG 1115+080 show a significant decrease between thefirst two observation epochs separated by a rest-frame timescale of ~ 1 year.This variability supports the intrinsic nature of these absorbers. Assuming theinterpretation that the high-energy absorption features arise from highlyionized Fe XXV we constrain the fraction of the total bolometric energyreleased by quasars PG 1115+080 and APM 08279+5225 into the IGM in the form ofkinetic energy to be epsilon_k = 0.64(-0.40,+0.52) (68% confidence), andepsilon_k =0.09(-0.05,+0.07), respectively. According to recent theoreticalstudies this range of efficiencies is large enough to influence significantlythe formation of the host galaxy and to regulate the growth of the centralblack hole.Comment: 20 pages, includes 5 figures, Accepted for publication in A