Multi-band Cross-correlated Radio Variability of the Blazar 3C 279

Опубликовано: 01 / 2024
Multi-band Cross-correlated Radio Variability of the Blazar 3C 279
Multi-band radio light curve of 3C279.For clearer visual presentation, the individual lightcurves are shown with offsets, which are provided in the inset label. The solid black and thin blue slanted lines connect the peaks of the first and second outbursts, respectively.

Mohana A Krishna; Gupta Alok C.; Marscher Alan P.; Sotnikova Yulia V.; Jorstad S. G.; Wiita Paul J.; Cui Lang; Aller Margo F.; Aller Hugh D.; Kovalev Yu. A.; Kovalev Y. Y.; Liu Xiang; Mufakharov T. V.; Popkov A. V.; Mingaliev M. G.; Erkenov A. K.; Nizhelsky N. A.; Tsybulev P. G.; Zhao Wei; Weaver Z. R.; Morozova D. A.

We present the results of our study of cross-correlations between long-term multi-band observations of the radio variability of the blazar 3C 279. More than a decade (2008-2022) of radio data were collected at seven different frequencies ranging from 2 GHz to 230 GHz. The multi-band radio light curves show variations in flux, with the prominent flare features appearing first at higher-frequency and later in lower-frequency bands. This behavior is quantified by cross-correlation analysis, which finds that the emission at lower-frequency bands lags that at higher-frequency bands. Lag versus frequency plots are well fit by straight lines with negative slope, typically ~-30 day/GHz. We discuss these flux variations in conjunction with the evolution of bright moving knots seen in multi-epoch VLBA maps to suggest possible physical changes in the jet that can explain the observational results. Some of the variations are consistent with the predictions of shock models, while others are better explained by a changing Doppler beaming factor as the knot trajectory bends slightly, given a small viewing angle to the jet.
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