Flare magnetic reconnection and relativistic particles in the 2003 October 28 event

¹ Department of Astronomy, Nanjing University, Nanjing 210093, PR China e-mail: chuan.li@ias.u-psud.fr; lic@nju.edu.cn
² Institut d'Astrophysique Spatiale, Bâtiment 121, Universit Paris-sud 11 and CNRS, Orsay 91405, France

Received: 19 December 2006
Accepted: 5 June 2007

Abstract

An X17.2 solar flare occurred on 2003 October 28, accompanied by multi-wavelength emissions and a high flux of relativistic particles observed at 1 AU. We present the analytic results of the TRACE, SOHO, RHESSI, ACE, GOES, hard X-ray (INTEGRAL satellite), radio (Ondeřejov radio telescope), and neutron monitor data. It is found that the inferred magnetic reconnection electric field correlates well with the hard X-ray, gamma-ray, and neutron emission at the Sun. Thus the flare's magnetic reconnection probably makes a crucial contribution to the prompt relativistic particles, which could be detected at 1 AU. Since the neutrons were emitted a few minutes before the injection of protons and electrons, we propose a magnetic-field evolution configuration to explain this delay. We do not exclude the effect of CME-driven shock, which probably plays an important role in the delayed gradual phase of solar energetic particles.