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A complete understanding of solar radio bursts requires developing numerical techniques which can connect large-scale activities with kinetic plasma processes. As a starting point, this study presents a numerical scheme combining three…

Solar and Stellar Astrophysics · Physics 2021-03-10 M. Yousefzadeh , H. Ning , Y. Chen

Content. Electron-cyclotron maser emission (ECME) is the favored mechanism for solar radio spikes and has been investigated extensively since the 1980s. Most studies relevant to solar spikes employ a loss-cone-type distribution of energetic…

Solar and Stellar Astrophysics · Physics 2021-08-04 Hao Ning , Yao Chen , Sulan Ni , Chuanyang Li , Zilong Zhang , Xiangliang Kong , Mehdi Yousefzadeh

Electron cyclotron maser emission (ECME) is regarded as a plausible source for the coherent radio radiations from solar active regions (e.g., solar radio spikes). In this Letter, we present a 2D3V fully kinetic electromagnetic…

Solar and Stellar Astrophysics · Physics 2021-11-24 Hao Ning , Yao Chen , Sulan Ni , Chuanyang Li , Zilong Zhang , Xiangliang Kong , Mehdi Yousefzadeh

A beam of super-thermal, hot electrons was injected into maxwellian plasma with a density gradient along a magnetic field line. 1.5D particle-in-cell simulations were carried out which established that the EM emission is produced by the…

Solar and Stellar Astrophysics · Physics 2014-04-07 Roman Pechhacker , David Tsiklauri

Magnetic reconnection is a key process that drives the energy release in solar flares. This process can occur at multiple locations along the coronal loop. The reconnection generates energetic electrons capable of exciting wave modes and…

Solar and Stellar Astrophysics · Physics 2025-04-02 Mehdi Yousefzadeh , Alexey Kuznetsov , Yao Chen , Mahboub Hosseinpour

Twisted magnetic fields should be ubiquitous in flare-producing active regions where the magnetic fields are strongly non-potential. It has been shown that reconnection in helical magnetic coronal loops results in plasma heating and…

Solar and Stellar Astrophysics · Physics 2016-01-20 R. F. Pinto , M. Gordovskyy , P. K. Browning , N. Vilmer

Evolution of a coronal loop in response to an impulsive energy release is numerically modelled. It is shown that the loop density evolution curves exhibit quasi-periodic perturbations with the periods given approximately by the ratio of the…

Astrophysics · Physics 2009-11-10 V. M. Nakariakov , D. Tsiklauri , A. Kelly , T. D. Arber , M. J. Aschwanden

Understanding the relationship among different emission components plays an essential role in the study of particle acceleration and energy conversion in solar flares. In flares where gradual and impulsive emission components can be readily…

Solar and Stellar Astrophysics · Physics 2015-06-15 Siming Liu , Youping Li , Lyndsay Fletcher

We use the cyclotron-maser theory to explain the core emission from the magnetosphere of pulsars. As a kind of direct and efficient maser type of emission, it can give rise to escaping radiation with extremely high brightness temperature…

Astrophysics · Physics 2009-10-30 Chun-yu Ma , Ding-yi Mao , De-yu Wang , Xin-ji Wu

Microwave emission of solar flares is formed primarily by incoherent gyrosynchrotron radiation generated by accelerated electrons in coronal magnetic loops. The resulting emission depends on many factors, including pitch-angle distribution…

Solar and Stellar Astrophysics · Physics 2015-05-30 Alexey A. Kuznetsov , Gelu M. Nita , Gregory D. Fleishman

Loop-aligned hydrodynamic modelings help better understand the thermodynamic evolution of flaring plasma confined in solar flare loops. Conventional loop modelings typically assume a uniform loop cross section. With a variation of the cross…

Solar and Stellar Astrophysics · Physics 2026-02-24 Yu Dai , Shihan Li , Wenlong Tang , Zhen Li , Mingde Ding

The high densities, long lifetimes, and narrow emission measure distributions observed in coronal loops with apex temperatures near 1 MK are difficult to reconcile with physical models of the solar atmosphere. It has been proposed that the…

Solar and Stellar Astrophysics · Physics 2010-04-08 Harry P. Warren , David M. Kim , Amanda M. DeGiorgi , Ignacio Ugarte-Urra

Context. The Sun is an active source of radio emission ranging from long duration radio bursts associated with solar flares and coronal mass ejections to more complex, short duration radio bursts such as solar S bursts, radio spikes and…

Solar and Stellar Astrophysics · Physics 2016-04-19 D. E. Morosan , P. Zucca , D. S. Bloomfield , P. T. Gallagher

Solar coronal shocks are very common phenomena in the solar atmosphere and are believed to be the drivers of solar type II radio bursts. However, the microphysical nature of these emissions is still an open problem. This paper proposes that…

Solar and Stellar Astrophysics · Physics 2015-06-19 G. Q. Zhao , L. Chen , D. J. Wu

With the elementary energy release events introduced in a previous paper (Liu & Fletcher 2009) we model the chromospheric evaporation in flaring loops. The thick-target hard X-ray (HXR) emission produced by electrons escaping from the…

Solar and Stellar Astrophysics · Physics 2014-11-20 Siming Liu , Feiran Han , Lyndsay Fletcher

Aims: Solar radio type II bursts are rarely seen at frequencies higher than a few hundred MHz. Since metric type II bursts are thought to be signatures of propagating shock waves, it is of interest to know how these shocks, and the type II…

Astrophysics · Physics 2009-11-13 S. Pohjolainen , J. Pomoell , R. Vainio

A simple mechanism for the generation of electromagnetic Zebra pattern emission is proposed. The mechanism is based on the generation of an ion-ring distribution in a magnetic mirror geometry in the presence of a properly directed…

Space Physics · Physics 2011-10-03 R. A. Treumann , R. Nakamura , W. Baumjohann

Aims: We identify the source of fast-drifting decimetric-metric radio emission that is sometimes observed prior to the so-called flare continuum emission. Fast-drift structures and continuum bursts are also observed in association with…

Astrophysics · Physics 2008-08-26 S. Pohjolainen

We investigated wave amplification through the Electron-Cyclotron-Maser mechanism. We calculated absorption and emission coefficients without any approximations, also taking into account absorption by the ambient thermal plasma. A power-law…

Astrophysics · Physics 2009-10-31 Amnon Stupp

Energetic electrons with power-law spectrum are most commonly observed in astrophysics. This paper investigates electron cyclotron maser emission (ECME) from the power-law electrons, in which strong pitch-angle anisotropy is emphasized. The…

Solar and Stellar Astrophysics · Physics 2016-05-25 G. Q. Zhao , H. Q. Feng , D. J. Wu , L. Chen , J. F. Tang , Q. Liu
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