Abstract
The distribution maps of the circular polarization degree and radio brightness have been analyzed for more than 40 flares based on the Nobeyama Radioheliograph data. It has been shown that the observed microwave emission is polarized in the ordinary mode in some flaring loop parts in six events. Based on a joint analysis of the photospheric magnetic field maps obtained from the HMI/SDO and MDI/SOHO magnetograph’s and the radio emission dynamics in different source parts, it has been concluded that the ordinary mode predominance in all six selected events can be connected with implementation of the longitudinal pitch-angle anisotropy of emitting electrons.
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References
Alisandrakis, C.E., Nindos, A., and Kundu, M.R., Evidence for ordinary mode emission from microwave burst, Sol. Phys., 1993, vol. 147, pp. 343–358.
Bastian, T.S., Benz, A.O., and Gary, D.E., Radio emission from solar flares, Annu. Rev. Astron. Astrophys., 1998, vol. 36, pp. 131–188.
Cohen, M.H., Magnetoionic mode coupling at high frequencies, Astrophys. J., 1960, vol. 131, pp. 664–680.
Dulk, G.A., Radio emission from the Sun and stars, Annu. Rev. Astron. Astrophys., 1985, vol. 23, pp. 169–224.
Fleishman, G.D. and Melnikov, V.F., Gyrosynchrotron emission from electrons with anisotropic pitch-angle distribution, Astrophys. J., 2003, vol. 587, pp. 823–835.
Fleishman, G., Altyntsev, A., and Meshalkina, N., Microwave signature of relativistic positrons in solar flares, Publ. Astron. Soc. Jpn., 2013, vol. 65, no. S7, pp. 1–5.
Kuznetsov, S.A. and Melnikov, V.F., Modeling the effect of plasma density on the dynamics of the microwave spectrum of solar flaring loops, Geomagn. Aeron. (Engl. Transl.), 2012, vol. 52, no. 7, pp. 883–891.
Melnikov, V.F., Pyatakov, N.P., and Shibasaki, K., Constraints for electron acceleration models in solar flares from microwave observations with high spatial resolution, The 3rd Hinode Science Meeting, December 1–4, 2009, ASP Conf. Ser. 454, San Franciso: Astronomical. Soc. Pac., 2012, pp. 321–324.
Morgachev, A.S., Kuznetsov, S.A., and Melnikov, V.F., Radio diagnostics of the solar flaring loop parameters by the forward fitting method, Geomagn. Aeron. (Engl. Transl.), 2014, vol. 54, no. 7, pp. 933–942.
Su, Y.N. and Huang, G.L., Polarization of loop-top and footpoint sources in microwave bursts, Astrophys. J., 2004, vol. 219, pp. 159–168.
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Morgachev, A.S., Melnikov, V.F. & Kuznetsov, S.A. Search for accelerated electron anisotropy signatures based on observed polarization of the flaring loop microwave emission. Geomagn. Aeron. 56, 1045–1051 (2016). https://doi.org/10.1134/S001679321608017X
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DOI: https://doi.org/10.1134/S001679321608017X