2005/03/01 by K. W. Smith, K. Smith, M. Güdel +2 · 4 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Circular polarization #EPIC #Energy budget #Flare #Polarization (electrochemistry) #Pulsars and Gravitational Waves Research #Radio frequency #Relativistic particle #Solar and Space Plasma Dynamics #Synchrotron #X-shaped radio galaxy #astro-ph
paper · pdf · doi:10.1051/0004-6361:20042054
12 pages, 10 figures
arxiv created 2005/03/01 · openalex publication_date 2005/05/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present lightcurves obtained in X-ray by the XMM-Newton EPIC cameras and simultaneous radio lightcurves obtained with the VLA for five active M-type flare stars. A number of flare events were observed, and by comparing radio with X-ray data, we consider various possible flare mechanisms. In cases where there seems to be a clear correlation between radio and X-ray activity, we use an energy budget argument to show that the heating which leads to the X-ray emission could be due to the same particles emitting in the radio. In cases where there is radio activity without corresponding X-ray activity, we argue that the radio emission is likely to arise from coherent processes involving comparatively few particles. In one case, we are able to show from polarization of the radio emission that this is almost certainly the case. Cases for which X-ray activity is seen without corresponding radio activity are more difficult to explain. We suggest that the heating particles may be accelerated to very high energy, and the resulting synchrotron radio emission may be beamed in directions other than the line of sight.