1 / 15

Coronal hard X-ray sources and associated decimetric/metric radio emissions

Coronal hard X-ray sources and associated decimetric/metric radio emissions. N. Vilmer D. Koutroumpa (Observatoire de Paris- LESIA) S.R Kane G. Hurford (Space Sciences Laboratory Berkeley). HXR in solar flares  acceleration and propagation of energetic electrons interacting at the Sun

ganya
Download Presentation

Coronal hard X-ray sources and associated decimetric/metric radio emissions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. HXR in solar flares  acceleration and propagation of energetic electrons • interacting at the Sun • Bulk of HXR emission from footpoints of flaring B loops by electrons accelerated • in the low corona (109-1010 cm-3) near the loop top • 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 • 10’’ above the SXR loop apex • Relatively hard spectrum • Located at slightly higher altitudes at higher X-ray energies. • 1 event (Sato, 2001) without footpoints • Extended source above 30 keV at h> 5104km From Masuda et al 1998

  3. Interpretation in the scheme of magnetic reconnection above (outside the bright soft X-ray loop) the loop top: • energization of electrons in the • reconnection site itself or • at the place where the downward hot plasma from the reconnection site collides with underlying closed B loops • Different types of interpretation for reconnection sites: • Loop with a cusp configuration (Masuda) • Emerging flux type configuration • Loop-loop reconnection cartoon from Masuda et al, 1998 • Here observations of coronal above the loop top HXR sources with • RHESSI and time evolution in the flare

  4. 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

  5. RHESSI images 12-25 keV • 10’’ above the limb • after 1307 UT

  6. movie_trace+hessi1225.htmlmovie_trace+hessi2550.html Comparison of RHESSI images with TRACE images at 195 Å =flare plasma at 15 MK • TRACE and RHESSI 12-25 keV images before 13:07 UT • (no coronal HXR sources) • movie_trace+hessi1225_125500.html • TRACE and RHESSI 12-25 keV and 25-50 keV images • after 13:07 UT • (coronal HXR of the event sources with most of the time no footpoints Most energetic part )

  7. RHESSI 25-50 keV images

  8. 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

  9. 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) NRH 327 MHz Flux at 3  in the flare region from the Nançay Radioheliograph + Images at 327 MHz NRH 236 MHz NRH 164 MHz

  10. 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).t 25-50 keV 327 MHz

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

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

  13. In the most energetic part of the HXR event, coronal HXR sources with no (permanent) footpoints Coronal HXR sources (> 10’’ ) above the limb, 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 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 footpoints: most of the loop structures connected to parts behind the limb. Only the emission from the region close to the reconnection sites(s) but rather loop-loop reconnections. Summary/discussion

  14. 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 small scale loops as seen from the earth • After abrupt reformation of low lying B field lines through sequence of loop-loop interactions, the B field reconfiguration may extend over larger distances and reach overlying open field lines seen from the earth : • possible acceleration sites for 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

More Related