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Title: TEMPORAL AND SPATIAL ANALYSES OF SPECTRAL INDICES OF NONTHERMAL EMISSIONS DERIVED FROM HARD X-RAYS AND MICROWAVES
Authors: Asai, Ayumi  kyouindb  KAKEN_id  orcid https://orcid.org/0000-0002-5279-686X (unconfirmed)
Kiyohara, Junko
Takasaki, Hiroyuki
Narukage, Noriyuki
Yokoyama, Takaaki
Masuda, Satoshi
Shimojo, Masumi
Nakajima, Hiroshi
Author's alias: 浅井, 歩
Keywords: acceleration of particles
Sun: corona
Sun: flares
Sun: radio radiation
Sun: X-rays, gamma rays
Issue Date: 1-Feb-2013
Publisher: IOP Publishing
Journal title: The Astrophysical Journal
Volume: 763
Issue: 2
Thesis number: 87
Abstract: We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and microwaves. We analyzed 12 flares observed by the Hard X-Ray Telescope aboard Yohkoh, Nobeyama Radio Polarimeters, and the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived from total fluxes of HXRs and microwaves. Except for four events, which have very soft HXR spectra suffering from the thermal component, these flares show a gap Δδ between the electron spectral indices derived from HXRs δ X and those from microwaves δμ (Δδ = δ X – δμ) of about 1.6. Furthermore, from the start to the peak times of the HXR bursts, the time profiles of the HXR spectral index δ X evolve synchronously with those of the microwave spectral index δμ, keeping the constant gap. We also examined the spatially resolved distribution of the microwave spectral index by using NoRH data. The microwave spectral index δμ tends to be larger, which means a softer spectrum, at HXR footpoint sources with stronger magnetic field than that at the loop tops. These results suggest that the electron spectra are bent at around several hundreds of keV, and become harder at the higher energy range that contributes the microwave gyrosynchrotron emission.
Rights: © 2013. The American Astronomical Society.
This is not the published version. Please cite only the published version.
この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。
URI: http://hdl.handle.net/2433/169957
DOI(Published Version): 10.1088/0004-637X/763/2/87
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