Emission of electromagnetic waves by proton beams propagating in nonuniform solar plasmas

• Published in: Astronomy and astrophysics (Berlin) 2007-08, Vol.470 (3), p.1117-1122
• Main Authors: Sakai, J. I., Nagasugi, Y.
• Format: Article
• Language: English
• Subjects: acceleration of particles; Astronomy; Earth, ocean, space; Exact sciences and technology; plasmas; shock waves; Sun: flares; Sun: radio radiation
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361:20066978

Aims.We investigate the dynamics of proton beams propagating along a uniform magnetic field, as well as across the magnetic field in nonuniform solar plasmas, paying attention to the emission process of electromagnetic waves. The aim is to understand a new solar-burst component emitting only in the terahertz range during the solar flare observed by Kaufmann et al. (2004, ApJ, 603, L121). Methods.We used a 2D3V, fully relativistic, electromagnetic particle-in-cell (PIC) simulation. Results.From the simulation where the proton beams propagate along a uniform magnetic field into the high-density region, we found that strong electromagnetic waves are generated behind the proton beams. When the proton beams propagate perpendicular to the magnetic field, we found that the extra-ordinary mode can be excited from two electron Bernstein waves through three-wave interactions. These simulation results could be applied to the electromagnetic wave emission from the solar photosphere during the solar flares.