E-Print Archive

There are 4290 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
* News 04/04/20 * The archive is using a new backend database. This has thrown up a few SQL errors in the last few days. If you have any issues please email adavey@nso.edu with either the number of eprint you are trying to edit or a link to your preprint.

Measurements of electron anisotropy in solar flares using albedo with RHESSI X-ray data. View all abstracts by submitter

Ewan Cameron Mackenzie Dickson   Submitted: 2012-10-25 12:16

The angular distribution of electrons accelerated in solar flares is a key parameter in the understanding of the acceleration and propagation mechanisms that occur there. However, the anisotropy of energetic electrons is still a poorly known quantity, with observational studies producing evidence for an isotropic distribution and theoretical models mainly considering the strongly beamed case. We use the effect of photospheric albedo to infer the pitch angle distribution of X-ray emitting electrons using Hard X-ray data from RHESSI. A bi-directional approximation is applied and a regularized inversion is performed for eight large flare events to deduce the electron spectra in both downward (towards the photosphere) and upward (away from the photosphere) directions. The electron spectra and the electron anisotropy ratios are calculated for broad energy range from about 10 and up to ~ 300 keV near the peak of the flares. The variation of electron anisotropy over short periods of time intervals lasting 4, 8 and 16 seconds near the impulsive peak has been examined. The results show little evidence for strong anisotropy and the mean electron flux spectra are consistent with the isotropic electron distribution. The 3-sigma level uncertainties, although energy and event dependent, are found to suggest that anisotropic distribution with anisotropy larger than ~ 3 are not consistent with the hard X-ray data. At energies above 150-200 keV, the uncertainties are larger and thus the possible electron anisotropies could be larger.

Authors: Dickson, E.C.M. and Kontar, E.P.
Projects: RHESSI

Publication Status: Accepted for publication in Solar Physics
Last Modified: 2012-10-26 14:54
Go to main E-Print page  Improved basis set for low frequency plasma waves  Resolving Azimuth Ambiguity Using Vertical Nature of Solar Quiet-Sun Magnetic Fields  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

Key
Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
Proper Orthogonal and Dynamic Mode Decomposition of Sunspot Data.
Statistical Properties of Superflares on Solar-type Stars: Results Using All of the Kepler Primary Mission Data
Turbulent viscosity and effective magnetic Prandtl number from simulations of isotropically forced turbulence
Time and Charge-Sign Dependence of the Heliospheric Modulation of Cosmic Rays
Bayesian Analysis of Quasi-periodic Pulsations in Stellar Flares
Cause and Kinematics of a Jetlike CME
The role of small-scale surface motions in the transfer of twist to a solar jet from a remote stable flux rope
Sub-second time evolution of Type III solar radio burst sources at fundamental and harmonic frequencies
Magnetically coupled atmosphere, fast sausage MHD waves, and forced magnetic field reconnection during the SOL2014-09-10T17:45 flare
Differential rotation of the solar corona: A new data-adaptive multiwavelength approach
Magnetic Helicity Flux across Solar Active Region Photospheres: I. Hemispheric Sign Preference in Solar Cycle 24
Seismological constraints on the solar coronal heating function
The Coronal Global Evolutionary Model: Using HMI Vector Magnetogram and Doppler Data to Determine Coronal Magnetic Field Evolution
Radio and X-ray Observations of Short-lived Episodes of Electron Acceleration in a Solar Microflare
Research progress based on observations of the New Vacuum Solar Telescope
Dynamics evolution of a solar active-region filament from quasi-static state to eruption: rolling motion, untwisting motion, material transfer, and chirality
Microwave Study of a Solar Circular Ribbon Flare
Precise Formation-Flying Telescope in Target-Centric Orbit: the Solar Case
Propagation Effects in Quiet Sun Observations at Meter Wavelengths
Twin Null-Point-Associated Major Eruptive Three-Ribbon Flares with Unusual Microwave Spectra

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey



© 2000-2020 Solar Physics Group - Montana State University