Space VLBI Observations Show [ITAL]T[/ITAL][TINF][ITAL]b[/ITAL][/TINF] ] 10[TSUP]12[/TSUP] K in the Quasar NRAO 530
Open Access
- 10 November 1998
- journal article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 507 (2), L117-L120
- https://doi.org/10.1086/311701
Abstract
We present here space-based VLBI observations with VSOP and a southern hemisphere ground array of the gamma-ray blazar NRAO 530 at 1.6 GHz and 5 GHz. The brightness temperature of the core at 1.6 GHz is $5 imes 10^{11}$ K. The size is near the minimum observable value in the direction of NRAO~530 due to interstellar scattering. The 5 GHz data show a single component with a brightness temperature of $sim 3 imes 10^{12}$ K, significantly in excess of the inverse Compton limit and of the equipartition brightness temperature limit (Readhead 1994). This is strong evidence for relativistic motion in a jet requiring model-dependent Doppler boosting factors in the range 6 to 60. We show that a simple homogeneous sphere probably does not model the emission region accurately. We favor instead an inhomogeneous jet model with a Doppler boosting factor of 15.Comment: 12 pages, 2 figures. Accepted for publication in ApJ Letter
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