# A connection between γ-ray and parsec-scale radio flares in the blazar 3C 273

M.M. Lisakov, Y. Y. Kovalev, T. Savolainen, T. Hovatta, A.M. Kutkin

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)

## Abstract

We present a comprehensive 5-43 GHz VLBA study of the blazar 3C 273 initiated after an onset of a strong $\gamma$-ray flare in this source. We have analyzed the kinematics of new-born components, light curves, and position of the apparent core to pinpoint the location of the $\gamma$-ray emission. Estimated location of the $\gamma$-ray emission zone is close to the jet apex, 2 pc to 7 pc upstream from the observed 7 mm core. This is supported by ejection of a new component. The apparent core position was found to be inversely proportional to frequency. The brightness temperature in the 7 mm core reached values up to at least $10^{13}$ K during the flare. This supports the dominance of particle energy density over that of magnetic field in the 7 mm core. Particle density increased during the radio flare at the apparent jet base, affecting synchrotron opacity. This manifested itself as an apparent core shuttle along the jet during the 7 mm flare. It is also shown that a region where optical depth decreases from $\tau\sim1$ to \$\tau
Original language English 4478-4493 16 Monthly Notices of the Royal Astronomical Society 468 4 https://doi.org/10.1093/mnras/stx710 Published - 2017 A1 Journal article-refereed

## Keywords

• techniques
• interferometric – galaxies
• jets – quasars
• individual
• 3C 273 – gamma-rays