1 research outputs found
Location of Decimetric Pulsations in Solar Flares
This work investigates the spatial relation between coronal X-ray sources and
coherent radio emissions, both generally thought to be signatures of particle
acceleration. Two limb events were selected during which the radio emission was
well correlated in time with hard X-rays. The radio emissions were of the type
of decimetric pulsations as determined from the spectrogram observed by
Phoenix-2 of ETH Zurich. The radio positions were measured from observations
with the Nancay Radioheliograph between 236 and 432 MHz and compared to the
position of the coronal X-ray source imaged with RHESSI. The radio pulsations
originated at least 30 - 240 Mm above the coronal hard X-ray source. The
altitude of the radio emission increases generally with lower frequency. The
average positions at different frequencies are on a line pointing approximately
to the coronal hard X-ray source. Thus, the pulsations cannot be caused by
electrons trapped in the flare loops, but are consistent with emission from a
current sheet above the coronal source.Comment: Solar Physics, in pres