We discover the significant (significance level of >99%) correlations between the fractional variation of the ionizing continuum and that of the C IV and/or Si IV BALs in each of 21 BAL quasars that have at least five-epoch observations from the Sloan Digital Sky Survey-I/II/III. This result reveals that the fluctuation of the ionizing continuum is the driver of most of these BAL variations. Among them, 17 show negative correlations and the other 4 positive correlations, which agrees with the prediction of photoionization models that absorption line variability response to ionization changes is not monotonic. 8 quasars out of 21 examples have been observed at least 30 times on rest-frame timescales as short as a few days, which reveals that changes in the incident ionizing continuum can cause BAL variability even in such a short period of time. In addition, we find that most of the 21 quasars show larger variation amplitude in Si IV than C IV, which reveals the ubiquity of saturation in these BALs (at least for C IV BALs).
@article{arxiv.1908.03844,
title = {Correlations between the Variation of the Ionizing Continuum and Broad Absorption Lines in Individual Quasars},
author = {Wei-Jian Lu and Ying-Ru Lin},
journal= {arXiv preprint arXiv:1908.03844},
year = {2019}
}
Comments
10 pages, 1 figure, accepted for publication in ApJ