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Coronal hard X-ray sources and associated radio emissions

Coronal hard X-ray sources and associated radio emissions. N. Vilmer D. Koutroumpa (Observatoire de Paris- LESIA; Thessaloniki University) S.R Kane G. Hurford (Space Sciences Laboratory Berkeley). Background: CORONAL ABOVE THE LOOP TOP SOURCES

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Coronal hard X-ray sources and associated radio emissions

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  1. Coronal hard X-ray sources and associated radio emissions N. Vilmer D. Koutroumpa (Observatoire de Paris- LESIA; Thessaloniki University) S.R Kane G. Hurford (Space Sciences Laboratory Berkeley)

  2. Background: CORONAL ABOVE THE LOOP TOP SOURCES • YOHKOH/HXT coronal above the loop top > 30 keV X-ray sources in impulsive flares (Masuda, 1994; Masuda et al., 1998) (< 6 events) • Compact above the loop top source together with double footpoint sources • Located at slightly higher altitudes at higher X-ray energies. From Masuda et al 1998 cartoon from Masuda et al, 1998

  3. Do we have such observations with RHESSI? Are they consistent with such a cartoon? A complementary view of one of the event presented here by Sui

  4. Coronal HXR sources GOES M2.5 AR 9893 AR 9893 N21 W81 large part behind the limb H 1310-1320-1332 N23 W88 SF AR 9893 < 1323- 1338 N19 W67 SF AR9901 H 8 days earlier Coronal HXR source from 13:07 UT Vilmer, Koutroumpa, Kane, Hurford, EGS

  5. RHESSI images 12-25 keV • (30%,50%,70%,90%) • 10’’ above the limb • after 1307 UT

  6. RHESSI 25-50 keV images grids from 7’’

  7. Steep non-thermal emission Above > 10 keV (-6.7)

  8. Comparison of RHESSI images with TRACE images at 195 Å =flare plasma at 15 MK (coalignment between EIT and Trace during the flare) • TRACE and RHESSI 12-25 keV images before 13:07 UT • (no coronal HXR sources)

  9. TRACE and RHESSI 12-25 keV images after 13:07 UT(coronal HXR sources with most of the time no footpoints Most energetic part of the event)

  10. TRACE and RHESSI 25-50 keV images after 13:07 UT(coronal HXR sources with most of the time no footpoints Most energetic part of the event)

  11. Coronal HXR sources (> 10’’ ) above the limb, displaced from the hot magnetic structures seen with TRACE? • 25-50 keV predominant coronal sources above 12-25 keV sources (faint footpoints close to max) • (see previous YOHKOH/HXT obs but more dynamical and more complicated fields?)

  12. Associated radio emissions?? 6-12 keV RHESSI • Gyrosynchrotron emission from energetic flare associated electrons in the cm/mm domain Observations at 3  from Bern Similarity between durations of 30 keV HXR and cm emissions from energetic electrons (as usually observed) 12-25 keV 25-50 keV 19.6 GHz 11.8 GHz 8.4 GHz

  13. Coherent radio emissions in dm/m wavelengths Spectrum ETH Zürich Radio type III bursts e beams in the corona limited  range (< 350 MHz) limited time range (30 s) No emission in the IP Medium (no electron escape) NRH 327 MHz Flux at 3  in the flare region from the Nançay Radioheliograph + Images at 327 MHz NRH 236 MHz NRH 164 MHz

  14. 3-6 keV 6-12 keV 12-25 keV Limited duration of Associated dm emissions Consistent with the observations that 10 to 15 % of HXR producing electrons have no detectable emission at decimeter and longer wavelengths (e.g. Simnett and Benz, 1986). 25-50 keV 327 MHz

  15. NRH 327 MHz during 4 bursts Between 131120 and 131140 RHESSI 25-50 keV

  16. Double source at the Time of the radio peak

  17. In the most energetic part of the HXR event, predominant coronal HXR sources above 25 keV with no (permanent) footpoints Coronal HXR sources (> 10’’ ) above the limb, with 25-50 keV displaced (above) the hot magnetic structures seen with TRACE 25-50 keV coronal sources above 12-25 keV sources Consistent with the previous (~ 6 ) observations with YOHKOH/HXT but More dynamic behaviour: from TRACE observations, suggestion of loop-loop interactions between 2 loop systems with one system apparently connected to parts of the AR behind the limb? Appearance of the coronal sources and of the most energetic part of the event at the time of the interaction. No permanent footpoints: confined energetic electrons? Coronal HXR source for the 16/04/02 flare

  18. cm and HXR emission: gyrosynchrotron emission from electrons in low-lying B loops • Most of the event: no dm/m emissions • No electron access to high or open B field lines seen from the earth • Energetic electrons are only present in low lying loops as seen from the earth • At the time of the radio burst the B field reconfiguration may reach overlying open field lines seen from the earth : • possible acceleration sites for dm radio emitting electrons • Radio dm/m emissions at the time of appearance of second component of 25-50 keV source indicating displacement of energy release site and possible electron access to new B lines. e-beams X-rays Simple 2D sketch?? More complex at 3D with several loop systems as suggested by TRACE

  19. RHESSI50-100 keVspectrograms 10/04/02 GOES M8.8 PHOENIX OSRA Radio 4 GHz to 1 MHz WIND

  20. RHESSI 40-65 keV 432 MHz (black) 327 MHz (dashed-dotted white) 164 MHz (dotted white) No emission below 327 MHz before 122753 UT Extension towards 164 MHz at 122843 UT New radio positions after 123048 UT 2nd HXR peak Extension to 12 MHz (electron path to high corona)

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