Solar energetic electrons, X-rays, and Radio Bursts

2006 ◽  
pp. 199-205
Author(s):  
R. P. Lin
Keyword(s):  
Radio Bursts ◽  
X Rays ◽  
Energetic Electrons

scholarly journals X-Ray Evidence for the Acceleration, Containment, and Emission of High Energy Flare Particles

1974 ◽  
Vol 57 ◽  
pp. 421-422 ◽  
Author(s):  
Kenneth J. Frost
Keyword(s):  
Cosmic Ray ◽  
High Energy ◽  
Solar Observatory ◽  
Time Structure ◽  
Radio Bursts ◽  
X Rays ◽  
Thermal Component ◽  
X Ray ◽  
Type Iii ◽  
Explosive Phase

An instrument aboard the Fifth Orbiting Solar Observatory has observed hard solar X-rays from January 1969 to May 1972. A large number of X-ray bursts generated by solar cosmic ray flares have been observed. The X-ray bursts consist, in general, of two non-thermal components. The earliest occurring non-thermal component, coincident with the explosive phase, consists of a group of one to about ten X-ray bursts that are, for each burst, approximately 10 s duration and symmetrical in rise and decay. The time structure and multiplicity of these bursts is remarkably similar to that found in type III radio bursts in the meterwave band. The spectra of these bursts steepens sharply at energies greater than 100 keV indicating a limit at this energy for electron acceleration during the explosive or flash phase of the flare. For several flares these multiple X-ray bursts have occurred in coincidence with a group of type III bursts.

scholarly journals On Special Features of Non-Thermal Solar X Radiation above 10 keV

1972 ◽  
Vol 14 ◽  
pp. 761-762
Author(s):  
G. Elwert ◽  
E. Haug
Keyword(s):  
Magnetic Field ◽  
Angular Distribution ◽  
Power Law ◽  
Impulsive Phase ◽  
X Rays ◽  
Energetic Electrons ◽  
X Ray ◽  
Preferred Direction ◽  
Field Lines ◽  
The Magnetic Field

The polarization and angular distribution of solar hard X radiation above 10 keV was calculated under the assumption that the X rays originate as bremsstrahlung from energetic electrons moving in a preferred direction. The source electrons are supposed to have a power-law spectrum. These conditions are to be expected in the impulsive phase of an X-ray burst. The spiral orbits of the electrons around the magnetic field lines are taken into account.

Theory of the Solar 22-Year Cycle

1971 ◽  
Vol 2 (1) ◽  
pp. 7-10 ◽  
Author(s):  
J. H. Piddington
Keyword(s):  
Magnetic Fields ◽  
Solar Surface ◽  
Velocity Fields ◽  
The Sun ◽  
Solar Magnetic Fields ◽  
Radio Bursts ◽  
X Rays ◽  
Plasma Velocity ◽  
Full Understanding ◽  
Satisfactory Theory

If there were no solar magnetic fields, then the most active feature observable on the Sun would be the hydrodynamic convection. There would be no sunspots, flares, prominences, plage, spicules, and no copious emissions of X-rays, energetic particles or radio bursts. These effects are all due to the presence of a changing pattern of magnetic fields which repeats every 22 years. While observations of electromagnetic phenomena are limited to the solar surface and atmosphere, a full understanding of these effects must include a satisfactory theory of the solar cycle and of the fields which evolve beneath the surface as a result of plasma velocity fields.

scholarly journals Comments on X-rays emitted by the sun

1965 ◽  
Vol 23 ◽  
pp. 57-59
Author(s):  
John C. Lindsay
Keyword(s):  
Solar Observatory ◽  
The Sun ◽  
Radio Bursts ◽  
X Rays ◽  
X Ray ◽  
Quiet Sun ◽  
Upper Limit

Observations from the first Orbiting Solar Observatory have set an upper limit of 3.40 ± 0.95 photons/cm2.s for the 20–100 keV X-ray flux from the “quiet” Sun. Eight impulsive and short-lived 20–100 keV X-ray bursts were observed which were associated with optical flares and cm radio bursts. The 2–8 Å X-ray flux from the “quiet” Sun was observed to be associated with plage groups on the Sun. The intensity for this 2–8 Å X-radiation was found to be quite variable, changes of 5% being observed almost hourly.

scholarly journals Fast Radio Bursts as crustal dynamical events induced by magnetic field evolution in young magnetars

2021 ◽  
Author(s):  
J.E. Horvath ◽  
M.G.B. de Avellar ◽  
L.S. Rocha ◽  
P.H.R.S. Moraes
Keyword(s):  
Magnetic Field ◽  
Gravitational Radiation ◽  
Soliton Solutions ◽  
Radio Bursts ◽  
X Rays ◽  
Simultaneous Emission ◽  
Field Evolution ◽  
Non Linear ◽  
The Magnetic Field

Abstract We revisit in this work a model for repeating Fast Radio Bursts based of the release of energy provoked by the magnetic field dynamics affecting a magnetar's crust. We address the basics of such a model by solving the propagation of the perturbation approximately, and quantify the energetics and the radiation by bunches of charges in the so-called {\it charge starved} region in the magnetosphere. The (almost) simultaneous emission of newly detected X-rays from SGR 1935+2154 is tentatively associated to a reconnection behind the propagation. The strength of $f$-mode gravitational radiation excited by the event is quantified, and more detailed studies of the non-linear (spiky) soliton solutions suggested.

Energetic electrons in solar flares: observational support for acceleration processes linked to magnetic reconnection

2021 ◽  
Author(s):  
Nicole Vilmer ◽  
Sophie Musset
Keyword(s):  
Solar Flares ◽  
Magnetic Energy ◽  
Imaging Spectroscopy ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
High Energy ◽  
X Rays ◽  
Energetic Electrons ◽  
Radio Imaging ◽  
Gyrosynchrotron Emission

<p>Efficient electron (and ion) acceleration is produced in association with solar flares. Energetic particles play a major role in the active Sun since they contain a large amount of the magnetic energy released during flares. Energetic electrons (and ions) interact with the solar atmosphere and produce high-energy X-rays and γ-rays. Energetic electrons also produce radio emission in a large frequency band through gyrosynchrotron emission processes in the magnetic fields of flaring active regions and conversion of plasma waves when e.g. propagating to the high corona towards the interplanetary medium. It is currently admitted that solar flares are powered by magnetic energy previously stored in the coronal magnetic field and that magnetic energy release is likely to occur on coronal currents sheets along regions of strong gradient of magnetic connectivity. However, understanding the connection between particle acceleration processes and the topology of the complex magnetic structures present in the corona is still a challenging issue. In this talk, we shall review some recent results derived from X-ray and radio imaging spectroscopy of solar flares bringing some new observational constraints on the localization of HXR/radio sources with respect to current sheets, termination shocks in the corona derived from EUV observations.</p>

Type III Radio Bursts and Langmuir Wave Excitation

2020 ◽  
Author(s):  
Gottfried Mann ◽  
Christian Vocks ◽  
Mario Bisi ◽  
Eoin Carley ◽  
Bartosz Dabrowski ◽  
...  
Keyword(s):  
Distribution Function ◽  
Interplanetary Space ◽  
Langmuir Wave ◽  
Velocity Distribution Function ◽  
Radio Bursts ◽  
Radio Waves ◽  
Langmuir Waves ◽  
Low Frequencies ◽  
Energetic Electrons ◽  
Type Iii

<p>Type III radio bursts are a common phenomenon the Sun’s nonthermal radio radiation. They appear as stripes of enhanced radio emission with a rapid drift from high to low frequencies in dynamic radio spectra. They are considered as the radio signatures of beams of energetic electrons travelling along magnetic field lines from the solar corona into the interplanetary space. With the ground based radio interferometer LOFAR and the instrument FIELDS onboard NASA’s “Parker Solar Probe” (PSP) , type III radio bursts can be observed simultaneously from high (10-240 MHz) to low frequencies (0.01-20 MHz) with LOFAR and PSP’s FIELDs, respectively. That allows to track these electron beams from the corona up to the interplanetary space. Assuming that a population of energetic electrons is initially injected, the velocity distribution function of these electrons evolves into a beam like one. Such distribution function leads to the excitation of Langmuir waves which convert into radio waves finally observed as type II radio bursts. Numerical calculations of the electron-beam-plasma interaction reveal that the Langmuir waves are excited by different parts of the energetic electrons at different distances in the corona and interplanetary space. This result is compared with special type III radio bursts observed with LOFAR and PSP’s FIELDS.</p>

Sign in / Sign up

Export Citation Format

Share Document