Astronomy and Astrophysics – Astrophysics
Scientific paper
Mar 2005
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005a%26a...432.1033z&link_type=abstract
Astronomy and Astrophysics, Volume 432, Issue 3, March IV 2005, pp.1033-1047
Astronomy and Astrophysics
Astrophysics
24
Sun: Flares, Sun: Particle Emission, Sun: X-Rays, Gamma Rays
Scientific paper
The numerical solutions of the time-dependent kinetic Fokker-Planck equation are presented for fast electrons injected from the solar corona into a flaring atmosphere and precipitating with energy and pitch-angle diffusion into a loop with a converging magnetic field. The electrons are assumed to lose their energy in Coulomb collisions with particles of the partially ionised ambient plasma and Ohmic heating owing to the electric field induced by the precipitating beam. The electric field induced by a precipitating electron beam is found to cause a return current beam, which comes back to the source in the corona with a wide pitch angle distribution. The return current is assumed to arise from the ambient plasma and from beam electrons scattered into negative pitch-angles. Energy and pitch-angle distributions of precipitating and return current electron beams at various atmospheric depths are presented along with the precipitating beam abundances, energy fluxes and resulting hard X-ray bremsstrahlung (photon) spectra for electron beams with power law energy spectra with spectral indices of 3, 5, 7 and initial energy fluxes of 108, 1010, 1012 erg cm-2 s-1. Energy distributions of the return current cover energies lower than 60 keV for weaker soft beams and increase to 65 keV for moderate soft beams, or to 70 75 keV for more intense and hard beams. The maxima are at 30 keV for weaker soft beams and are shifted towards higher energies, up to 50 keV, for harder and more intense beams. As a result, the photon spectra of hard X-ray emission emitted from a flaring atmosphere are found to have a broken power-law (elbow-type) shape with a higher energy part retaining the spectral index δhigh associated with the electron beam's initial index and varying slightly with the beam parameters. However, the lower energy part of the X-ray photon spectra shows a much smaller increase or even a substantial decrease of its spectral index δlow for more intense or harder beams. These simulated broken power-law photon spectra produced by precipitating electron beams with a single spectral index agree reasonably well with the photon energy spectra from the flares of 20 and 23 July, 2002 observed by the RHESSI payload.
Figures [see full text]-[see full text] are only available in electronic form at http://www.edpsciences.org
Gordovskyy Mykola
Zharkova Valentin
No associations
LandOfFree
The kinetic effects of electron beam precipitation and resulting hard X-ray intensity in solar flares does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The kinetic effects of electron beam precipitation and resulting hard X-ray intensity in solar flares, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The kinetic effects of electron beam precipitation and resulting hard X-ray intensity in solar flares will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1213092