GBT17B-210

Evolution of High Brightness Temperature AGN Cores with RadioAstron

Abstract

The RadioAstron AGN survey has detected 163 targets on SVLBI baselines up to 28 Earth diameters, with measured brightness temperatures ranging up to ~>10^14 K, well in excess of inverse Compton and equipartition limits.
The distribution of brightness temperatures, and its upper bound, have fundamental implications for the emission mechanisms and kinematics of relativistic outflows from supermassive black holes.
This follow up project builds on the success of the survey and involves monitoring the brightest and most compact targets selected from the survey results in order to study the properties and physics of their variable emission.
This strategy maximizes our chances of detecting more sources with brightness temperatures in excess of 10^14 K.
We request 162 hours of the GBT time for the period July 2017 - June 2018 inclusive to observe 32 of the brightest AGNs, and up to 4 flaring AGNs with RadioAstron and GBT at L- and K-bands.
As the most sensitive available ground telescope, GBT is crucial to the project to provide the required sensitivity to measure high brightness temperatures, given the small size of the space telescope and the low correlated flux densities.
These observations will attain the highest resolution available from direct astronomical observations.

Investigators

Name Institution
Michael Johnson California at Santa Barbara, University of; Center for Astrophysics | Harvard & Smithsonian
Tony Zensus National Radio Astronomy Observatory; Max-Planck-Institut für Radioastronomie
James Anderson Deutsches GeoForschungsZentrum
Michael Bietenholz York University; Hartebeesthoek Radio Astronomy Observatory
Leonid Gurvits Joint Institute for Very Long Baseline Interferometry European Research Infrastructure Consortium
Petr Voytsik Lebedev Physical Institute
Kirill Sokolovsky Illinois at Urbana-Champaign, University of
Nikolai Kardashev Lebedev Physical Institute
Yuri Kovalev * Max-Planck-Institut für Radioastronomie
GBT Operator Green Bank Observatory

* indicates the PI