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Title: Dynamic Spectral Imaging of Decimetric Fiber Bursts in an Eruptive Solar Flare

Abstract

Fiber bursts are a type of fine structure that is often superposed on type IV radio continuum emission during solar flares. Although studied for many decades, its physical exciter, emission mechanism, and association with the flare energy release remain unclear, partly due to the lack of simultaneous imaging observations. We report the first dynamic spectroscopic imaging observations of decimetric fiber bursts, which occurred during the rise phase of a long-duration eruptive flare on 2012 March 3, as obtained by the Karl G. Jansky Very Large Array in 1–2 GHz. Our results show that the fiber sources are located near and above one footpoint of the flare loops. The fiber source and the background continuum source are found to be co-spatial and share the same morphology. It is likely that they are associated with nonthermal electrons trapped in the converging magnetic fields near the footpoint, as supported by a persistent coronal hard X-ray source present during the flare rise phase. We analyze three groups of fiber bursts in detail with dynamic imaging spectroscopy and obtain their mean frequency-dependent centroid trajectories in projection. By using a barometric density model and magnetic field based on a potential field extrapolation, we further reconstruct themore » 3D source trajectories of fiber bursts, for comparison with expectations from the whistler wave model and two MHD-based models. We conclude that the observed fiber burst properties are consistent with an exciter moving at the propagation velocity expected for whistler waves, or models that posit similar exciter velocities.« less

Authors:
; ;  [1]
  1. Center for Solar-Terrestrial Research, New Jersey Institute of Technology, University Heights, Newark, NJ 07102 (United States)
Publication Date:
OSTI Identifier:
22679748
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 848; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; DENSITY; EMISSION; EXCITATION SYSTEMS; EXTRAPOLATION; FINE STRUCTURE; FREQUENCY DEPENDENCE; GHZ RANGE; HARD X RADIATION; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; SOLAR FLARES; SOLAR RADIO BURSTS; SPECTROSCOPY; SUN; TRAPPING; WHISTLERS; X-RAY SOURCES

Citation Formats

Wang, Zhitao, Chen, Bin, and Gary, Dale E., E-mail: zw56@njit.edu. Dynamic Spectral Imaging of Decimetric Fiber Bursts in an Eruptive Solar Flare. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8EE5.
Wang, Zhitao, Chen, Bin, & Gary, Dale E., E-mail: zw56@njit.edu. Dynamic Spectral Imaging of Decimetric Fiber Bursts in an Eruptive Solar Flare. United States. doi:10.3847/1538-4357/AA8EE5.
Wang, Zhitao, Chen, Bin, and Gary, Dale E., E-mail: zw56@njit.edu. Fri . "Dynamic Spectral Imaging of Decimetric Fiber Bursts in an Eruptive Solar Flare". United States. doi:10.3847/1538-4357/AA8EE5.
@article{osti_22679748,
title = {Dynamic Spectral Imaging of Decimetric Fiber Bursts in an Eruptive Solar Flare},
author = {Wang, Zhitao and Chen, Bin and Gary, Dale E., E-mail: zw56@njit.edu},
abstractNote = {Fiber bursts are a type of fine structure that is often superposed on type IV radio continuum emission during solar flares. Although studied for many decades, its physical exciter, emission mechanism, and association with the flare energy release remain unclear, partly due to the lack of simultaneous imaging observations. We report the first dynamic spectroscopic imaging observations of decimetric fiber bursts, which occurred during the rise phase of a long-duration eruptive flare on 2012 March 3, as obtained by the Karl G. Jansky Very Large Array in 1–2 GHz. Our results show that the fiber sources are located near and above one footpoint of the flare loops. The fiber source and the background continuum source are found to be co-spatial and share the same morphology. It is likely that they are associated with nonthermal electrons trapped in the converging magnetic fields near the footpoint, as supported by a persistent coronal hard X-ray source present during the flare rise phase. We analyze three groups of fiber bursts in detail with dynamic imaging spectroscopy and obtain their mean frequency-dependent centroid trajectories in projection. By using a barometric density model and magnetic field based on a potential field extrapolation, we further reconstruct the 3D source trajectories of fiber bursts, for comparison with expectations from the whistler wave model and two MHD-based models. We conclude that the observed fiber burst properties are consistent with an exciter moving at the propagation velocity expected for whistler waves, or models that posit similar exciter velocities.},
doi = {10.3847/1538-4357/AA8EE5},
journal = {Astrophysical Journal},
number = 2,
volume = 848,
place = {United States},
year = {Fri Oct 20 00:00:00 EDT 2017},
month = {Fri Oct 20 00:00:00 EDT 2017}
}