Structure Function and Variability Mechanism of Quasars from SDSS Stripe 82

• Published in: arXiv.org
• Main Author: Voevodkin, Alexey
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 30.08.2011
• Subjects: Breaking; Computer simulation; Image quality; Light curve; Monte Carlo simulation; Photometry; Physics - Cosmology and Nongalactic Astrophysics; Quasars; Sky surveys (astronomy)
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1107.4244

Theoretical predictions for the ensemble quasar structure function are tested using multi-epoch observations of Stripe 82 collected by the Sloan Digital Sky Survey. We reanalyze the entire available volume of the g-band imaging data using difference image photometry and build high quality light curves for 7562 spectroscopically confirmed quasars. Our structure function includes ~4.8x10^6 pairs of measurements and covers a wide range of time lags between 3 days and 6.9 years in the quasar rest frame. A broken power-law fit to this data shows the presence of two slopes alpha_1=0.33 and alpha_2=0.79 with the break at ~42 days. The structure function compiled using only flux increases is slightly lower than that for variations of the opposite sign, revealing a slight asymmetry between the leading and trailing edge of a typical flare. The reality of these features is confirmed with monte-carlo simulations. We give simple interpretation of the results in the frames of existing theoretical models.