Day-scale variability of 3C 279
and searches for correlations
in gamma-ray, X-ray, and Optical bands


R. C. Hartman, M. Villata, T. J. Balonek,
D. L. Bertsch, H. Bock, M. Böttcher, et al.
Astrophysical Journal, 558, 583 (2001)


Abstract

Light curves of 3C 279 are presented in optical (R-band), X-rays (RXTE/PCA), and gamma-rays (CGRO/EGRET) for 1999 Jan - Feb and 2000 Jan - Mar. During both of those epochs the gamma-ray levels were high, and all three observed bands demonstrated substantial variation, on time scales as short as one day. Correlation analyses provided no consistent pattern, although a rather significant optical/gamma-ray correlation was seen in 1999, with a gamma-ray lag of ~ 2.5 days, and there are other suggestions of correlations in the light curves. For comparison, correlation analysis is also presented for the gamma-ray and X-ray light curves during the large gamma-ray flare in 1996 Feb and the two gamma-bright weeks leading up to it; the correlation at that time was strong, with a gamma-ray/X-ray offset of no more than 1 day.

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