Multi-epoch observations of extremely high-velocity emergent broad absorption

We present the discovery of the highest velocity C IV broad absorption line to date in the z = 2.47 quasar SDSS J023011.28+005913.6, hereafter J0230. In comparing the public DR7 and DR9 spectra of J0230, we discovered an emerging broad absorption trough outflowing at ~60 000 km s-1,which we refer to as trough A. In pursuing followup observations of trough A, we discovered a second emergent CIV broad absorption trough outflowing at ~40 000 km s^-1, namely trough B. In total, we collected seven spectral epochs of J0230 that demonstrate emergent and rapidly (~10 d in the rest-frame) varying broad absorption. We investigate two possible scenarios that could cause these rapid changes: bulk motion and ionization variability. Given our multi-epoch data, we were able to rule out some simple models of bulk motion, but have proposed twomore realistic models to explain the variability of both troughs. Trough A is likely an augmented 'crossing disc' scenario with the absorber moving at 10 000 < v(km s^-1) < 18 000. Trough B can be explained by a flow-tube feature travelling across the emitting region at 8000 < v(km s^-1) < 56 000. If ionization variability is the cause for the changes observed, trough A's absorber has n_e ≥ 724 cm^-3 and is at requal ≥ 2.00 kpc, or is at r < 2.00 kpc with no constraint on the density; trough B's absorber either has n_e ≥ 1540 cm^-3 and is at r_equal ≥ 1.37 kpc, or is at r < 1.37 kpc with no constraint on the density.