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arXiv · 1107.4244

Structure Function and Variability Mechanism of Quasars from SDSS Stripe 82

Alexey Voevodkin
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Abstract

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.

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Alexey Voevodkin. 2011-07-21. Structure Function and Variability Mechanism of Quasars from SDSS Stripe 82. https://arxiv.org/abs/1107.4244

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