Coronal hard x ray sources and associated radio emissions
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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

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

  • 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


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


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



RHESSI 25-50 keV images

grids from 7’’


Steep non-thermal emission

Above > 10 keV

(-6.7)


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)


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)


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)



Associated radio emissions
Associated radio emissions?? from the hot magnetic structures seen with TRACE?

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


Coherent radio emissions in dm/m wavelengths from the hot magnetic structures seen with TRACE?

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


3-6 keV from the hot magnetic structures seen with TRACE?

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


NRH 327 MHz from the hot magnetic structures seen with TRACE?

during 4 bursts

Between 131120 and 131140

RHESSI

25-50 keV


Double source at the from the hot magnetic structures seen with TRACE?

Time of the radio peak


Coronal hxr source for the 16 04 02 flare

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


  • 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


Rhessi 50 100 kev spectrograms
RHESSI in low-lying B loops 50-100 keVspectrograms

10/04/02 GOES M8.8

PHOENIX

OSRA

Radio

4 GHz to

1 MHz

WIND


RHESSI in low-lying B loops

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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