E-Print Archive

There are 3783 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
Analysis of intermittency in submillimeter radio and Hard X-Rays during the impulsive phase of a solar flare  

C. Guillermo Giménez de Castro   Submitted: 2016-05-25 22:28

We present an analysis of intermittent processes occurred during the impulsive phase of the flare SOL2012-03-13, using hard X-rays and submillimeter radio data. Intermittency is a key characteristic in turbulent plasmas and have been a analyzed recently for Hard X-rays data only. Since in a typical flare the same accelerated electron population is believed to produce both Hard X-rays and gyrosynchrotron, we compare both time profiles searching for intermittency signatures. For that we define a cross-wavelet power spectrum, that is used to obtain the Local Intermittency Measure or LIM. When greater than 3, the square LIM coefficients indicate a local intermittent process. The LIM2 coefficient distribution in time and scale helps to identify avalanche or cascade energy release processes. We find two different and well separated intermittent behaviors in the submillimeter data: for scales greater than 20 s, a broad distribution during the rising and maximum phases of the emission seems to favor a cascade process; for scales below 1 s, short pulses centered on the peak time, are representative of avalanches. When applying the same analysis to Hard X-rays, we find only the scales above 10 s producing a distribution related to a cascade energy fragmentation. Our results suggest that different acceleration mechanisms are responsible for tens of keV and MeV energy ranges of electrons.

Authors: C.G. Giménez de Castro, P.J.A. Simões, J.-P. Raulin, O.M. Guimarães Jr.
Projects: None

Publication Status: Accepted for publication , under editorial revision
Last Modified: 2016-05-27 12:34
Go to main E-Print page  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

A burst with double radio spectrum observed up to 212 GHz  

C. Guillermo Giménez de Castro   Submitted: 2012-09-04 06:27

We study a solar flare that occurred on September 10, 2002, in active region NOAA 10105 starting around 14:52 UT and lasting approximately 5 minutes in the radio range. The event was classified as M2.9 in X-rays and 1N in Hα . Solar Submillimeter Telescope observations, in addition to microwave data give us a good spectral coverage between 1.415 and 212 GHz. We combine these data with ultraviolet images, hard and soft X-rays observations and full-disk magnetograms. Images obtained from Ramaty High Energy Solar Spectroscopic Imaging data are used to identify the locations of X-ray sources at different energies and to determine the X-ray spectrum, while ultra violet images allow us to characterize the coronal flaring region. The magnetic field evolution of the active region is analyzed using Michelson Doppler Imager magnetograms. The burst is detected at all available radio-frequencies. X-ray images (between 12 keV and 300 keV) reveal two compact sources and 212 GHz data, used to estimate the radio source position, show a single compact source displaced by 25'' from one of the hard X-ray footpoints. We model the radio spectra using two homogeneous sources, and combine this analysis with that of hard X-rays to understand the dynamics of the particles. Relativistic particles, observed at radio wavelengths above 50 GHz, have an electron index evolving with the typical soft-hard-soft behaviour.

Authors: Giménez de Castro, C.G.; Cristiani, G.D.; Simões, P.J.A.; Mandrini, C.H.; Correia, E.; Kaufmann,P.
Projects: None

Publication Status: Solar Physics: accepted, subject to editorial corrections
Last Modified: 2012-09-05 13:41
Go to main E-Print page  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

A very narrow gyrosynchrotron spectrum during a solar flare  

C. Guillermo Giménez de Castro   Submitted: 2006-07-07 08:24

During the rising phase of the radio burst of August 30, 2002, at ~ 1328 UT a short pulse with a duration of approximately 4 seconds was observed. Here we present a multiwavelength analysis, including microwave and X-ray. Its background-subtracted radio spectrum ranges only from 5 to 12 GHz with a maximum flux density of approximately 900 s.f.u. at 7 GHz and a steep optically thin spectral index α ~ 8. The hard X-ray pulse emission above the background in the range of 10 - 150 keV observed by RHESSI is coincident in time with the microwave observation. Hard X-ray images reveal very compact ( ~ 10'') footpoint sources. A distribution of accelerated electrons represented by a double power law, with delta_low = 5.3 and delta_high = 13 (break energy = 250 keV), was used to compute the expected gyrosynchrotron and thick target bremsstrahlung fluxes of a homogeneous source. We interpret the very steep electron index above the energy break to represent a high energy cutoff. With these parameters, our results reproduce the observations well. Nevertheless, they pose the still unanswered question about the mechanism that has slectively accelerated these electrons.

Authors: C.G. Giménez de Castro, J.E.R. Costa, A.V.R. Silva, P.J.A. Simões, E. Correia, A. Magun
Projects: RHESSI

Publication Status: accepted on June 13, 2006, for publication in A&A
Last Modified: 2006-07-11 10:23
Go to main E-Print page  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 


Key
Go to main E-Print pageGo to main E-Print page.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
Delete AbstractDelete abstract.

Abstracts by Author
Analysis of intermittency in submillimeter radio and Hard X-Rays during the impulsive phase of a solar flare
A burst with double radio spectrum observed up to 212~GHz
A very narrow gyrosynchrotron spectrum during a solar flare

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



© 2003 Solar Physics Group - Montana State University