Diapositive%201

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Diagnostics and constraints for relativistic
electron and ion acceleration in solar
flares N. Vilmer LESIA Observatoire
de Paris
Ascona_June 7-11 2005
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X/?? -ray spectrum
Thermal components
T 2 10 7 K T 4 10 7 K
Electron bremsstrahlung
Ultrarelativistic Electron Bremsstrahlung
?-ray lines (ions gt 3 MeV/nuc)
SMM/GRS Phebus/Granat Observations GAMMA1 GRO GONG
Pion decay radiation (ions gt 100
MeV/nuc) sometimes with neutrons
RHESSI Energy range
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?-ray and neutron event on 03/06/82

• (from Chupp et al, 1987) -Time extended neutron
  production at the Sun ( 600s)
• First GeV protons accelerated in ?t lt16s at the
  beginning of the flare
• Neutron Emissivity at the Sun 7.4 1031 E2.4
  Neutrons/MeV/sr for 100ltElt2000 MeV
• - Spectral slope in agreement with the one
  deduced from neutron decay proton measurements

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?-ray and neutron event on 24/05/90

• 24 May solar flare GOES X9.3, N36 W76
• One of the largest neutron event
• Ngt100 MeV 3.5 1030 n sr-1
• Impulsive phase ? 75 MeV (2nd peak)
• Extended phase, duration gt 8 minutes
• High-energy ? -rays ? 100 MeV
• Pion-decay radiation from 2nd peak of the
  impulsive phase

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?-ray and neutron event on 24/05/90
From Talon et al., 1993 Debrunner et al 1997
High Energy ?-rays Solar neutrons
PHEBUS/GRANAT observations
Deduced solar neutron production time
profile (i.e. pion time profile)
NM CLIMAX observations of solar neutrons and
prediction for a time extended neutron
production
Spectral evolution of high-energy ?-rays
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Background subtracted count spectra From
PHEBUS/GRANAT Full line one of the best fits
with electron and pion contributions Dotted
line electron contribution
?-ray lines
Background subtracted count spectrum From 300 keV
to 100 MeV Full line one of the best fits with
one electron bremsstrahlung component pion
contribution Dotted line electron
component Electron bremsstrahlung component Ae
1 10 5 ? 2 Eroll 40 MeV Proton
component ?2 Ntot 8 1031 Emax 750 MeV
Vilmer et al, 2003
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• Proton spectra and numbers from pion decay
  radiation and ?-ray line radiation and neutron
  observations?
• Do we have a single energetic ion population from
  a few MeV/nuc to a few GeV/nuc

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• Ion spectrum with ??2 from a few Mev to Emax
  no compatibility
• Ion spectrum with ??3 from a few Mev to Emax
  only with Emax 750 MeV BUT GeV neutron
  production!!
• Ion spectrum with ??4 from a few Mev to Emax
  OK if Emax gt 2 GeV for spectra 1 to 3 BUT not
  enough pion production for spectrum 4!!
• No single shape of energetic ions from MeV to GeV
• Evidence of spectral breaks? Other forms of
  accelerated energetic spectra?
• Also found for other events (e.g. Kocharov)
• (see some of the simulations of particle
  acceleration by Dauphin et al)

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X/?? -ray spectrum
Thermal components
T 2 10 7 K T 4 10 7 K
Electron bremsstrahlung
Ultrarelativistic Electron Bremsstrahlung
?-ray lines (ions gt 3 MeV/nuc)
Phebus/Granat observations
Pion decay radiation (ions gt 100
MeV/nuc) sometimes with neutrons
RHESSI Energy range
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Bremsstrahlung and Synchrotron Emitting Electrons
(I)

• Simple relationship between the spectral indexes
  of cm-mm and HXR/GR producing electrons
• Spectral index ? from X-ray obs
• Thick target production from electrons
• Electron flux F(E,t) ?x from X-ray obs
• Simple relationship between electron flux in the
  X-ray source and instantaneous number of
  electrons in the gyrosynchrotron emitting source
  (?r)
• F(E,t) N(E,t)/T(E) with T(E) escape time
• ?r ?x ? 1
• Gyrosynchrotron
• Note also ?obs  ?L2 ?B
• Higher frequencies from
  higher energy electrons

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Bremsstrahlung and Synchrotron Emitting Electrons
(II)

• Mm-wave emission (86 GHz) produced by high
  energy electrons (?1 MeV) with a flatter spectrum
  than 100 keV X-ray spectrum (e.g. Kundu et al,
  1994, White, 1999)
• Early in the flare production of relativistic
  electrons on short time scales
• 2 components of electron populations or result of
  acceleration process?

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Electron-Dominated Events

• First observed with SMM (Rieger et al, 1993)
• Short duration (s to 10 s)
• high energy (gt 10 MeV) bremsstrahlung emission
• No detectable GRL flux
• Photon spectrum gt 1 MeV (?X?-1.52.0)
• For 2 PHEBUS events
• if Wigt1MeV/nuc ? Wegt20 keV
• No detectable GRL above continuum
• Weak GRL flares?

Vilmer et al (1999)
BATSE
PHEBUS
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Bremsstrahlung and Synchrotron Emitting Electrons
(III) Electron  broken  energy spectra

• Many evidence from HXR/GR observations that
  hardening of electron spectra above a few hundred
  keV (i.e. electron dominated disk event but also
  GRL events)
• Evolution of the break energy in the course
• of the event
• Relation between mm/cm emitting electrons and
  electrons above Eb

PHEBUS Bern Trottet et al (1998)
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Trottet, Vilmer et al. 1998
Bern and PHEBUS/GRANAT observations
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Trottet, Vilmer et al. 1998

• ? radio spectral index
• Peak c
• - from HXR/GR
• ? 4.1 for EltEb
• ? 1.5 for EgtEb
• observed
• ? 1.5
• Peak d
• - from HXR/GR
• ? 2.7 for EltEb
• ? 1.2 for EgtEb
• observed
• ? 1.3

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Bremsstrahlung and Synchrotron Emitting Electrons
(IV) Production of submm emissions by
ultrarelativistic electrons?
First detection at 212 GHz Now also at 405
GHZ (Kaufman et al, 2002,2004)
Gyrosynchrotron emission From power law energy
distribution with ?? 2.7 Corresponding to a mid
size electron-dominated event above gt 100 kev (no
observations)
From Trottet, Raulin, Kaufman et al, 2002
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Bremsstrahlung and Synchrotron Emitting Electrons
(V) Production of submm emissions by
ultrarelativistic electrons?
II
Rise?
spectre
III
Radio emitting electron spectra harder than the
X-ray observed one Consistent with ? 2.3 in II
and ? 3.5 in III and B500G But electrons of
energies around 10 MeV needed Breaks? (from Lüthi
et al, 2004) To be further investigated with
flares also observed above a few MeV
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3 November 2003 event
ltagt -1.2 (centimétrique) ? d -2.7 (électrons)
From Dauphin et al, 2005
?1.22-0.9? (Dulk et March, 1982)
Analyse spectrale X/centimétrique
094910-095000
095810-095840
095740-095800
095840-095950
095700-095730
ltagt2eme phase -1.2
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Hypothèse électrons rayonnent dans les X en
cible épaisse (Brown, 1971) propagation libre
entre sources X et centimétrique
?d1(photons) -1.7
Analyse spectrale de RHESSI ? Indice spectral des
photons -1.6
Rear detectors (2 and 7 excluded) no pulse pile
up correction  Binning code 12  1 keV 3 to 60
keV 2 keV to 120 keV 5 keV to 250 keV 10 keV to
2250 keV 50 keV 2250 keV to 7200 keV 200 keV 7.2
MeV to 17 MeV special binning around 511 keV
and 2.2 MeV line     2003/11/03 095849.999
2003/11/03 100129.999 4.00969 3.26291
581.398 1.61146 1.4129 0  
Flux total observé
Flux du bruit de fond
raie du bruit de fond
Population délectrons énergétique émettant le
rayonnement X gt 500 keV compatible avec le
rayonnement centimétrique
Fit reproduisant le mieux le flux total le flux
du bruit de fond
-1.6
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November 4, 2003 flare spectra
SST
OVSA
Itapetinga
A new component Starting from 200 GHz? In
relationship with High frequency radiations
Kaufmann et al, 2004)
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Observations Of high energy radiation By
SONG/CORONAS Myagkova et al, 2004
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2003 October 28
Also for the 28 October flare See Trottet et al
Koronas
Trottet et al. 2005 in prep.