The variability timescales and brightness temperatures of radio flares from stars to supermassive black holes

Understand

In this paper we compile the analysis of ~ 200 synchrotron flare events from ~ 90 distinct objects/events for which the distance is well established, and hence the peak luminosity can be accurately estimated.

• For each event we measure this peak and compare it to the rise and decay timescales, as fit by exponential functions, which allows us in turn to estimate a minimum brightness temperature for all the events.
• The astrophysical objects from which the flares originate vary from flare stars to supermassive black holes in active galactic nuclei, and include both repeating phenomena and single cataclysmic events (such as supernovae and gamma ray burst afterglows).
• The measured timescales vary from minutes to longer than years, and the peak radio luminosities range over 22 orders of magnitude.