The Cause of Photospheric and Helioseismic Responses to Solar Flares: High-Energy Electrons or Protons?

Abstract

Analysis of the hydrodynamic and helioseismic effects in the photosphere during the solar flare of 2002 July 23, observed by MDI/SOHO, and high-energy images from RHESSI show that these effects are closely associated with sources of the hard X-ray emission but that no such effects existed in the centroid region of the flare's gamma-ray emission. These results demonstrate that, contrary to expectations, these hydrodynamic and helioseismic responses (``sunquakes'') are more likely to be caused by accelerated electrons than by high-energy protons. A series of multiple impulses of high-energy electrons form a hydrodynamic source that is moving in the photosphere at supersonic speed. This moving source plays a critical role in the formation of the anisotropic wave front of sunquakes.