English

HST and Ground-Based Spectroscopy of Quasar Outflows: From Mini-BALs to BALs

Astrophysics of Galaxies 2018-12-05 v1

Abstract

Quasar outflows have been posited as a mechanism to couple super-massive black holes to evolution in their host galaxies. We use multi-epoch spectra from the Hubble Space Telescope and ground-based observatories to study the outflows in seven quasars that have CIV outflow lines ranging from a classic BAL to weaker/narrower "mini-BALs" across rest wavelengths of at least 850 A˚\AA to 1650 A˚\AA. The CIV outflow lines all varied within a time frame of \leq 1.9 yrs (rest). This includes equal occurrences of strengthening and weakening plus the emergence of a new BAL system at -38,800 km/s accompanied by dramatic strengthening in a mini-BAL at -22,800 km/s. We infer from \sim1:1 doublet ratios in PV and other lines that the BAL system is highly saturated with line-of-sight covering fractions ranging from 0.27 to 0.80 in the highest to lowest column density regions, respectively. Three of the mini-BALs also provide evidence for saturation and partial covering based on \sim1:1 doublet ratios. We speculate that the BALs and mini-BALs form in similar clumpy/filamentary outflows, with mini-BALs identifying smaller or fewer clumps along our lines of sight. If we attribute the line variabilities to clumps crossing our lines of sight at roughly Keplerian speeds, then a typical variability time in our study, \sim1.1 yrs, corresponds to a distance \sim2 pc from the central black hole. Combining this with the speed and minimum total column density inferred from the PV BAL, NHN_H \gtrsim 2.5×\times1022^{22} cm2^{-2}, suggests that the BAL outflow kinetic energy is in the range believed to be sufficient for feedback to galaxy evolution.

Keywords

Cite

@article{arxiv.1703.10691,
  title  = {HST and Ground-Based Spectroscopy of Quasar Outflows: From Mini-BALs to BALs},
  author = {E. A. Moravec and F. Hamann and D. M. Capellupo and S. M. McGraw and J. C. Shields and P. Rodríguez Hidalgo},
  journal= {arXiv preprint arXiv:1703.10691},
  year   = {2018}
}

Comments

20 pages, 5 figures, accepted to MNRAS for publication