Friday, October 15, 2010
Historical Photometry of BAL quasars
The paper on dramatic variability in a BAL quasar that I submitted last week to MNRAS (see Wed. Oct. 6 post) is now accepted; look for it on arXiv next week.
York undergrad Ted Rudyk visited Wednesday and Thursday. We were investigating whether old photographic magnitudes could be used to look for other cases of 'overlapping trough' BAL quasars transitioning between heavily absorbed (red) and unabsorbed (blue) states. We found a few cases of potential long-term variations in BAL trough strength as traced by g-r color (see graph for SDSS J090212.4+592415 above), but we're limited by the photometric accuracy of the old POSS-I and DPOSS magnitudes. My colleague Zeljko Ivezic and his former grad student Branimir Sesar have produced recalibrated photographic magnitudes for quasars from SDSS DR2, but there are no plans to extend the recalibration to DR7 quasars. If such a recalibration did get done, we could look at long-term quasar color variability in BAL vs. non-BAL quasars, including searching for quasars which aren't BALs now but were in the past. Could also take a stab at this using SDSS Stripe 82 data from Zeljko's current grad student Chelsea MacLeod.
Ted and I talked to Smita Mathur and Matthias Dietrich about possible BAL variability projects with the MDM 2.4-meter telescope to which OSU has access. Biweekly to monthly monitoring of quasars with high-velocity outflows and known X-ray properties seems to be the best bet.
Talked to Phil Hopkins about searching for radial inflow (with ALMA and in quasar spectra) as a signature of the single-armed spiral waves that feed AGNs in his simulations.
On Friday gave this journal club on distance measurements to BAL outflows.