The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

Abstract

The high brightness temperatures, $T_{\mathrm{b}}\gtrsim 10^{13}$ K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to 240,000 km we find two characteristic angular scales in the quasar core, about 100 $\mu$as and 10 $\mu$as. Some indications of scattering substructure are found. Very high brightness temperatures, $T_{\mathrm{b}}\ge 10^{13}$ K, are estimated at 4.8 GHz and 22 GHz even taking into account the refractive scattering. Our findings suggest a clear dominance of the particle energy density over the magnetic field energy density in the core of this quasar.

14 pages, 9 figures

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• MOJAVE -- XXII. Brightness temperature distributions and geometric profiles along parsec-scale AGN jets
• Correlations between $\gamma$-ray luminosity and magnetization of the jet as well as relativistic electron injection power:cases for Mrk 421, 3C 454.3 and 3C 279
• Inverse Compton Scattering of the Central Source Photons as an X-ray Emission Mechanism on Kiloparsec Scales in PKS 1127-145
• Revisiting 3C 279 jet morphology with space VLBI at 26 microarcsecond resolution
• Inverse Compton Scattering of Radiation from a Central Source as a Possible Mechanism for the Formation of X-Ray Radiation from Kiloparsec Jets of Core-Dominated Quasars
• Direct VLBI Detection of Interstellar Turbulence Imprint on a Quasar: TXS 2005+403
• Interstellar scintillation of sources B0821+394 and B1812+412 as observed by the LPA LPI radio telescope