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Synchrotron radiation from accelerated electrons above the photosphere of a relativistic ejecta is a natural candidate for the dominant process for the prompt GRB emission. There is however a tension between the predicted low-energy…

High Energy Astrophysical Phenomena · Physics 2025-01-29 Frédéric Daigne , Željka Bošnjak

The effect of pitch-angle anisotropy of fast electrons on generation of nonthermal radio emission is studied. Incoherent gyrosynchrotron radiation is shown to depend strongly on the anisotropy. In particular, the spectral index of…

Astrophysics · Physics 2007-05-23 Gregory D. Fleishman

The dominant radiation mechanism that produces the prompt emission in gamma-ray bursts (GRBs) remains a major open question. Spectral information alone has proven insufficient in elucidating its nature. Time-resolved linear polarization has…

High Energy Astrophysical Phenomena · Physics 2021-04-21 Ramandeep Gill , Jonathan Granot

The spectrum of electromagnetic emission generated by relativistic electrons scattered on small-scale random magnetic fields, implied by current models of the magnetic field generation in the gamma-ray burst sources, is considered. The…

Astrophysics · Physics 2009-11-10 Gregory D. Fleishman

Observations of the solar corona and the solar wind discover that the solar wind is unsteady and originates from the impulsive events near the surface of the Sun's atmosphere. How solar coronal activities affect the properties of the solar…

Solar and Stellar Astrophysics · Physics 2018-11-14 H. Che

Strong coronal magnetic field, when present, manifests itself as bright microwave sources at high frequencies produced by gyroresonant (GR) emission mechanism in thermal coronal plasma. The highest frequency at which this emission is…

Solar and Stellar Astrophysics · Physics 2023-02-15 V. V. Fedenev , S. A. Anfinogentov , G. D. Fleishman

The phenomena observed at the Sun have a variety of unique radio signatures that can be used to diagnose the processes in the solar atmosphere. The insights provided by radio obervations are further enhanced when they are combined with…

Solar and Stellar Astrophysics · Physics 2018-06-26 E. P. Kontar , A. Nindos

Gyrosynchrotron radiation is produced by solar flares, and can be used to infer properties of the accelerated electrons and magnetic field of the flaring region. This microwave emission is highly dependent on many local plasma parameters,…

Solar and Stellar Astrophysics · Physics 2019-03-12 Christopher M. J. Osborne , Paulo J. A. Simões

Massive stars form in dense and massive molecular cores. The exact formation mechanism is unclear, but it is possible that some massive stars are formed by processes similar to those that produce the low-mass stars, with accretion/ejection…

Astrophysics · Physics 2008-11-26 A. T. Araudo , G. E. Romero , V. Bosch-Ramon , J. M. Paredes

We study the synchrotron radiation as the observed non-thermal X-ray emission from old pulsars ($\gtrsim1-10$Myr) to investigate the particle acceleration in their magnetospheres. We assume that the power-law component of the observed X-ray…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Shota Kisaka , Shuta J. Tanaka

The pulsar radio emission originates from regions below 10% of the light cylinder radius. This requires a mechanism where coherent emission is excited in relativistic pair plasma with frequency $\nu_{cr}$ which is below the plasma frequency…

High Energy Astrophysical Phenomena · Physics 2017-09-27 Dipanjan Mitra

Polarisation measurements of solar flares at millimetre-waves were used to investigate the magnetic field configuration of the emitting sources. We analyse two solar flares (SOL2013-02-17 and SOL2013-11-05) observed by the POlarisation…

Solar and Stellar Astrophysics · Physics 2020-05-05 Douglas F. da Silva , Paulo J. A. Simões , R. F. Hidalgo Ramírez , Adriana Válio

Hot magnetic stars often exhibit incoherent circularly polarized radio emission thought to arise from gyro-synchrotron emission by energetic electrons trapped in the circumstellar magnetosphere. Theoretical scalings for electron…

Solar and Stellar Astrophysics · Physics 2023-08-16 B. Das , S. P. Owocki

Solar flares are due to the catastrophic release of magnetic energy in the Sun's corona, resulting in plasma heating, mass motions, particle acceleration, and radiation emitted from radio to $\gamma$-ray wavelengths. They are associated…

Solar and Stellar Astrophysics · Physics 2018-10-16 Dale E. Gary , Timothy S. Bastian , Bin Chen , Gregory D. Fleishman , Lindsay Glesener

Synchrotron emission of relativistic particles in magnetic fields is a process of paramount importance in astrophysics. Although known for over thirty years, there are still aspects of this radiative process that have received little…

Astrophysics · Physics 2009-11-07 Roberto Aloisio , Pasquale Blasi

Electrons/positrons produced in a pulsar magnetosphere emit synchrotron radiation, which is widely believed as the origin of the non-thermal X-ray emission detected from pulsars. Particles are produced by curvature photons emitted from…

High Energy Astrophysical Phenomena · Physics 2015-03-03 Shota Kisaka , Shuta J. Tanaka

During solar flares a large amount of electrons with energies greater than 20 keV is generated with a production rate of typically $10^{36}$ s$^{-1}$. A part of them is able to propagate along open magnetic field lines through the corona…

Solar and Stellar Astrophysics · Physics 2015-11-11 F. Breitling , G. Mann , C. Vocks

The cause of excess spectral line broadening (non-thermal velocity) is not definitively known, but given its rise before and during flaring, the causal processes hold clues to understanding the triggers for the onset of reconnection and the…

Solar and Stellar Astrophysics · Physics 2024-01-23 James McKevitt , Robert Jarolim , Sarah Matthews , Deborah Baker , Manuela Temmer , Astrid Veronig , Hamish Reid , Lucie Green

Type III radio bursts are radio emissions associated with solar flares. They are considered to be caused by electron beams traveling from the solar corona to the solar wind. Magnetic reconnection is a possible accelerator of electron beams…

Plasma Physics · Physics 2021-03-17 Xin Yao , Patricio A. Muñoz , Jörg Büchner , Xiaowei Zhou , Siming Liu

Two coherent radio emission mechanisms operate in stellar coronae: plasma emission and cyclotron emission. They directly probe the electron density and magnetic field strength respectively. Most stellar radio detections have been made at…

Solar and Stellar Astrophysics · Physics 2020-11-11 H. K. Vedantham