Particle acceleration by a solar flare termination shock.
Chen BHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. bin.chen@njit.edu.
Bastian TSNational Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA.
Shen CHarvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA.
Gary DENew Jersey Institute of Technology, 323 Martin Luther King Boulevard, Newark, NJ 07102, USA.
Krucker SUniversity of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA. University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch, Switzerland.
Glesener LUniversity of California, Berkeley, 7 Gauss Way, Berkeley, CA 94720, USA. University of Minnesota, Twin Cities, 116 Church Street SE, Minneapolis, MN 55455, USA.
English
Solar flares--the most powerful explosions in the solar system--are also efficient particle accelerators, capable of energizing a large number of charged particles to relativistic speeds. A termination shock is often invoked in the standard model of solar flares as a possible driver for particle acceleration, yet its existence and role have remained controversial. We present observations of a solar flare termination shock and trace its morphology and dynamics using high-cadence radio imaging spectroscopy. We show that a disruption of the shock coincides with an abrupt reduction of the energetic electron population. The observed properties of the shock are well reproduced by simulations. These results strongly suggest that a termination shock is responsible, at least in part, for accelerating energetic electrons in solar flares.