Solving the puzzle of discrepant quasar variability on monthly time scales implied by SDSS and CRTS datasets
Abstract
SDSS imaging survey has provided a time-resolved photometric dataset which greatly improved our understanding of the quasar optical continuum variability: data for monthly and longer time scales are consistent with a damped random walk. Recently, newer data obtained by CRTS (Catalina Real-Time Transient Survey) provided puzzling evidence for enhanced variability, compared to SDSS results, on monthly time scales. Quantitatively, SDSS results predict about 0.06 mag rms variability for timescales below 50 days, while CRTS data show about a factor of two larger rms for spectroscopically confirmed SDSS quasars. Our analysis presented here has successfully resolved this discrepancy as due to slightly underestimated photometric error estimates provided by the CRTS image processing pipelines. The photometric error correction factors, derived from detailed analysis of non-variable SDSS standard stars that were re-observed by CRTS, are about 20-30%, and result in a quasar variability behavior fully consistent with earlier SDSS results.
- Publication:
-
American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016
- Bibcode:
- 2016AAS...22724335S