Frequency rising sub-THz emission from solar flare ribbons

Kontar, E. P., Motorina, G. G., Jeffrey, Natasha, Tsap, Y. T., Fleishman, G. D. and Stepanov, A. V. (2018) Frequency rising sub-THz emission from solar flare ribbons. Astronomy & Astrophysics, 620. A95. ISSN 0004-6361

Preview

Text aa34124-18.pdf - Published Version Download (507kB) | Preview

Abstract

Observations of solar flares at sub-THz frequencies (millimetre and sub-millimetre wavelengths) over the last two decades often show a spectral component rising with frequency. Unlike a typical gyrosynchrotron spectrum decreasing with frequency or a weak thermal component from hot coronal plasma, the observations can demonstrate a high flux level (up to ∼104 solar flux units at 0.4 THz) and fast variability on sub-second timescales. Although, many models have been put forward to explain the puzzling observations, none of them has clear observational support. Here we propose a scenario to explain the intriguing sub-THz observations. We show that the model, based on free-free emission from the plasma of flare ribbons at temperatures 104 − 106 K, is consistent with all existing observations of frequency-rising sub-THz flare emission. The model provides a temperature diagnostic of the flaring chromosphere and suggests fast heating and cooling of the dense transition region plasma.

Actions (login required)

View Item

Downloads