We report on an X-ray and optical/ultraviolet (UV) study of eight broad absorption line (BAL) to non-BAL transforming quasars at z ≈ 1.7-2.2 over 0.29-4.95 rest-frame years with at least three spectroscopic epochs for each quasar from the SDSS, BOSS, Gemini, and ARC 3.5m telescopes. New Chandra observations obtained for these objects show that their values of αox and Δαox, as well as their spectral energy distributions, are consistent with those of non- BAL quasars. Moreover, our targets have X-ray spectral shapes that are, on average, consistent with weakened absorption with an effective power-law photon index of Γeff = 1.69-0.25 +0.25. The newer Gemini and ARC 3.5m spectra reveal that the BAL troughs have remained absent since the BOSS observations where the BAL disappearance was discovered. The X-ray and optical/UV results in tandem are consistent with at least the X-ray-absorbing material moving out of the line of sight, leaving an X-ray-unabsorbed non-BAL quasar. The UV absorber might have become more highly ionized (in a shielding-gas scenario) or also moved out of the line of sight (in a wind-clumping scenario).
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science