RHESSI Investigations of the Neupert Effect in Solar Flares Brian R. Dennis AAS/SPD Meeting 6 June 2002
Dec 14, 2015
RHESSI Investigations of the Neupert Effect in Solar Flares
Brian R. Dennis
AAS/SPD Meeting
6 June 2002
The Neupert Effect
• The time integral of the hard X-ray emission closely matches the temporal variation of the soft X-ray emission.
• Implies that accelerated electrons that produce the hard X-rays also heat the plasma that produces the soft X-rays.
RHESSI Contribution
• RHESSI observes both the soft X-rays (down to ~3 keV) and the hard X-rays with the same detectors.
• RHESSI also provides 2 arcsecond imaging capability in both soft and hard X-rays.
• RHESSI’s temporal resolution for images is 2 s for a complete set of spatial Fourier components.
• The spatially integrated time resolution is limited only by counting statistics.
RHESSI’s Limitations
• Suffers pulse pile up when the rates exceed ~10,000 counts per detector per second.
• Shutters moved into FOV when dead time reaches ~10%. Limits lower energy response below ~10 keV.
• K-escape photons contaminate low energy counts with higher energy emission.
10 April 2002
GOES 10 1 - 8 Å
Time derivative GOES 1 - 8 Å
RHESSI Light Curves6 – 12 keV12 – 25 keV25 – 50 keV50 – 100 keV
Start of X1.5 Flare on 21 April 2002TRACE images at 195 Å, RHESSI 12 – 25 keV contours
00:42:50 – 00:43:10 UT 00:48:54 – 00:49:14 UT
X1.5 Flare on 21 April 2002TRACE 195Å images and RHESSI contours at times of hard X-ray peaks
12-25 keV 50 – 100 keV
01:15:43 – 01:16:03 UT 01:23:27 – 01:23:47 UT