cme-driven interplanetary shocks
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Spectral Properties of Heavy Ions Spectral Properties of Heavy Ions Associated with Interplanetary Shocks Associated with Interplanetary Shocks
at 1 AUat 1 AU
SHINE 2004SHINE 2004Big Sky, Montana Big Sky, Montana
M. I. Desai M. I. Desai University of Maryland, College Park, MD 20742, USAUniversity of Maryland, College Park, MD 20742, USA
Co-Authors: Co-Authors: G. M. Mason: University of MarylandG. M. Mason: University of Maryland
C.M.S.Cohen & M. E. Wiedenbeck: SRL, Caltech, CA C.M.S.Cohen & M. E. Wiedenbeck: SRL, Caltech, CA J. E. Mazur: Aerospace CorpJ. E. Mazur: Aerospace Corp
J. R. Dwyer: Florida Institute of TechnologyJ. R. Dwyer: Florida Institute of TechnologyR.E. Gold & S. M. Krimigis: JHU/APLR.E. Gold & S. M. Krimigis: JHU/APL
C.W.Smith: University of New HampshireC.W.Smith: University of New HampshireQ. Hu: IGPP, UC Riverside, CAQ. Hu: IGPP, UC Riverside, CA
R. M. Skoug: Los Alamos National LaboratoryR. M. Skoug: Los Alamos National Laboratory
Spectral Properties of Heavy Ions Spectral Properties of Heavy Ions Associated with Interplanetary Shocks Associated with Interplanetary Shocks
at 1 AUat 1 AU
SHINE 2004SHINE 2004Big Sky, Montana Big Sky, Montana
M. I. Desai M. I. Desai University of Maryland, College Park, MD 20742, USAUniversity of Maryland, College Park, MD 20742, USA
Co-Authors: Co-Authors: G. M. Mason: University of MarylandG. M. Mason: University of Maryland
C.M.S.Cohen & M. E. Wiedenbeck: SRL, Caltech, CA C.M.S.Cohen & M. E. Wiedenbeck: SRL, Caltech, CA J. E. Mazur: Aerospace CorpJ. E. Mazur: Aerospace Corp
J. R. Dwyer: Florida Institute of TechnologyJ. R. Dwyer: Florida Institute of TechnologyR.E. Gold & S. M. Krimigis: JHU/APLR.E. Gold & S. M. Krimigis: JHU/APL
C.W.Smith: University of New HampshireC.W.Smith: University of New HampshireQ. Hu: IGPP, UC Riverside, CAQ. Hu: IGPP, UC Riverside, CA
R. M. Skoug: Los Alamos National LaboratoryR. M. Skoug: Los Alamos National Laboratory
CME-driven Interplanetary ShocksCME-driven Interplanetary Shocks
“Ambient”
(Desai et al. 2001, ApJ 553, L89 & 2003, ApJ, 588, 1149).
• Surveyed 72 shocks
between Oct. 1997-Oct.
2002
• 3He ions accelerated in
45 IP shocks
Pre-shock intervals provide a “proxy” for ambient particles in the IP medium
Intensity-time profiles Intensity-time profiles for an IP shockfor an IP shock
Ambient and SEP Ambient and SEP Abundances Abundances
Ambient and SEP Ambient and SEP Abundances Abundances
Ambient Ambient
material material
comprises comprises
~30% from ~30% from
impulsive impulsive
flares, and flares, and
~70% from ~70% from
large gradual large gradual
SEPsSEPs
Gradual SEPs
Impulsive SEPs
Upstream Material
10-2
10-1
100
C N O Ne MgSi S Ca Fe
12 1416 20 24 2832 40 56
Mass (AMU)
(Desai et al. 2003 ApJ, 588, 1149).
IP Shock compared with solar wind IP Shock compared with solar wind abundancesabundances
0
1
2
3
4
1 2 3 4 5 6Mass/Charge (AMU e-1)
m = 1.22 ± 0.23
c = 0.40 ± 0.22
cu
2 =3.34; =1.45 10P x-3
= 0.43; =0.13r p
4He C
Mg
Ne
N
O
Si
S
Fe
GI = + *[c m MIQO/MOQI]
(Desai et al. 2003 ApJ, 588, 1149).
• Shock abundances are
poorly correlated with
solar wind abundances
• No clear dependence on
M/Q
• Difficult to understand in
terms of rigidity-
dependent acceleration of
solar wind ions
IP Shock compared with ambient suprathermal IP Shock compared with ambient suprathermal abundancesabundances
0.2
0.4
0.6
0.8
2.0
1.0
1 2 3 4 5 6Mass/Charge (AMU e-1)
m = -0.64 ± 0.05
c = 0.63 ± 0.04
=4.39;P=2.56x10-5
r = -0.92; p=7.8x10-5
cu
2
(logGI) = + *[c m MIQO/MOQI]
4He N
CO
Ne
MgSi
S
Ca Fe
(Desai et al. 2003 ApJ, 588, 1149).
• Shock abundances are
well correlated with
ambient suprathermal
abundances
• Exhibit a M/Q-dependent
depletion
• Consistent with rigidity-
dependent shock
acceleration of ambient
suprathermals
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
10-4
10-3
10-2
10-1
100
101
102
103
10-2
10-1
100
101
22 23 24 25 26 27 28 29
1999 June (UT)
10-1
100
101
ACE/ULEIS C, O, Fe Intensities
ACE/ULEIS C/O ratio
ACE/ULEIS Fe/O ratio
S2
0.16-0.23 MeV n-1 (x10)
0.91-1.28 MeV n-1
OCFe
0.2 MeV n-1
1.0 MeV n-1
0.2 MeV n-1
1.0 MeV n-1
Ambient
(a)
(b)
(c)
Shock
Fe/O at IP shocks is Fe/O at IP shocks is
depleted relative to depleted relative to
ambient values ambient values
Larger decrease at Larger decrease at
higher energy higher energy
Energy Spectra during an IP Energy Spectra during an IP shock: shock:
All Spectra fitted by All Spectra fitted by j = jj = j00EE--
exp(-E/Eexp(-E/E00))
Parameter Carbon Oxygen Iron
No. of Points 8 10 8
j0 4.64 0.87 9.32 1.21 3.17 1.49
1.36 0.11 1.33 0.09 1.08 0.27
E0 0.69 0.09 0.72 0.06 0.35 0.06
2 0.87 0.91 0.88
10-1 100 101
Energy (MeV n-1)
10-3
10-2
10-1
100
101
102
103 2001, day 98::0426-1719 UT
Carbon
Oxygen
IronACE/ULEIS
however and E0 are coupled; Use only 0.1-0.5 MeV n-1 to obtain the power-law indices
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
Spectral indices of C, O, & Fe Spectral indices of C, O, & Fe Spectral indices of C, O, & Fe Spectral indices of C, O, & Fe
ACE/ULEIS: 0.1-0.5 MeV n-1
N = 72; r = 0.98;p ~ 0% N = 72; r = 0.79;p = 4.4 x10 -14%
0
1
2
3
4
0 1 2 3 4
O Spectral Index
0
1
2
3
4
0 1 2 3 4
O Spectral Index
(a) (b)
ACE/ULEIS: 0.1-0.5 MeV n-1
Differences in Fe and O indices are at odds Differences in Fe and O indices are at odds with injection of a mono-energetic seed with injection of a mono-energetic seed populationpopulation
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
O e-folding energy vs. shock O e-folding energy vs. shock parameters parameters
O e-folding energy vs. shock O e-folding energy vs. shock parameters parameters
0.1
1.0
10
0.1
1.0
10
0 15 30 45 60 75 90
Shock Normal Angle [deg.]qBn
( ) [ Shock speed upstream km s-1]VS
10 100 1000
( )a ( )b
= 57; = -0.04; = 76%N r p = 51; = 0.09; = 52%N r p
E-folding energy is independent of local shock E-folding energy is independent of local shock parametersparameters
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
0 1 2 3 4 50
1
2
3
4
5
(M+2)/(2M-2)
N = 60; r ~ 0.09; p ~ 51%
ACE/ULEIS 0.1-0.5 MeV n-1
Spectral index is poorly correlated with compression ratio, M
Results are at odds with predictions of simple steady-state models
2-hr. av. O spectral index vs. 2-hr. av. O spectral index vs. (M+2)/(2M-2) (M+2)/(2M-2)
2-hr. av. O spectral index vs. 2-hr. av. O spectral index vs. (M+2)/(2M-2) (M+2)/(2M-2)
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
22 23 24 25 26 27
2001 November (UT)
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
101
102
103
0.14
0.27
0.55
1.09
2.19
4.37
8.55
14.35
25.20
51.35
ACE ULEIS + SIS Oxygen Intensities
MeV n-1
S
S15W34
Ambient
IP shock event measured by ULEIS & IP shock event measured by ULEIS & SISSIS
IP shock event measured by ULEIS & IP shock event measured by ULEIS & SISSIS
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
Energy spectra measured by ULEIS & Energy spectra measured by ULEIS & SISSIS
Energy spectra measured by ULEIS & Energy spectra measured by ULEIS & SISSIS
10-1
101
103
105
107
10-2
10-1
100
101
10-1 100 101 102
Kinetic Energy (MeV n-1)
10-1 100 101 102
Kinetic Energy (MeV n-1)
solid symbols = ULEISopen symbols = SIS
solid symbols = ULEISopen symbols = SIS
event #61 event #61
(a) (b)
O
C
Fe
C/O
Fe/O
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
10-1 100 101
Kinetic Energy (MeV n-1)
10-5
10-3
10-1
100
103
10-2
10-1
100
101
10-5
10-3
10-1
100
103
10-5
10-3
10-1
100
103
10-1 100 101
Kinetic Energy (MeV n-1)10-1 100 101
Kinetic Energy (MeV n-1)
10-1 100 101
Kinetic Energy (MeV n-1)10-1 100 101
Kinetic Energy (MeV n-1)10-1 100 101
Kinetic Energy (MeV n-1)
10-2
10-1
100
101
10-2
10-1
100
101
C
O
Fe
CO
FeC
O
Fe
(a) (b) (c)
(d) (e) (f)
event #13
event #13
event #18
event #18
event #37
event #37
C/O
Fe/O
C/O
Fe/O
C/O
Fe/O
3 Classes of Fe/O energy-dependence 3 Classes of Fe/O energy-dependence 3 Classes of Fe/O energy-dependence 3 Classes of Fe/O energy-dependence
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
Energy-dependence of Fe/OEnergy-dependence of Fe/O Energy-dependence of Fe/OEnergy-dependence of Fe/O
0.01 0.1 1.0
Fe/O (0.22 MeV n-1)
0.01
0.1
1.0
0.01
0.1
1.0
0.01 0.1 1.0
Fe/O (0.22 MeV n-1)
0.01 0.1 1.0
Fe/O (0.22 MeV n-1)
0.01
0.1
1.0
N = 68 N = 33 N = 12
ACE/ULEIS ACE/ULEIS ACE/ULEIS & ACE/SIS
(a) (b) (c)
Fe = Fe/O (0.62 MeV/n.)
Fe/O (0.22 MeV/n.)
(Adapted from Desai et al. 2004, To appear in ApJ. Aug. 20, 2004)
FeFe vs. vs. 33He/He/44He ratio; He ratio; 33He/He/44He ratio vs. He ratio vs. BnBn
Extreme Events Only Extreme Events OnlyFeFe vs. vs. 33He/He/44He ratio; He ratio; 33He/He/44He ratio vs. He ratio vs. BnBn
Extreme Events Only Extreme Events Only
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
10-3
10-2
10-1
100
0 30 60 90
Shock Normal Angle, qBn [ .]deg
10 -3 10 -2 10 -1 1003 /He 4 He ratio
( )b( )a
3He/4He > 2%
N= 43;r= 0.08; p = 63.7%
3He/4He > 2%
N= 43;r= 0.56; p = 1.2x10-2%
m = 0.19 ± 0.06
c = 2.05 ± 0.41
1.0
0.2
0.4
0.6
0.8
2.0
3.0
4.0
FeFe vs. vs. 33He/He/44He ratio; He ratio; 33He/He/44He ratio vs. He ratio vs. BnBn
All events All events
FeFe vs. vs. 33He/He/44He ratio; He ratio; 33He/He/44He ratio vs. He ratio vs. BnBn
All events All events
33He/He/44He ratio vs. Injection Threshold Speed, VHe ratio vs. Injection Threshold Speed, Vinjinj = = VVSS*sec(*sec(BnBn))
33He/He/44He ratio vs. Injection Threshold Speed, VHe ratio vs. Injection Threshold Speed, Vinjinj = = VVSS*sec(*sec(BnBn))
Most IP shocks including the 3 with rising Fe/O ratios have Vinj<2*Vsw
3He/4He ratio and Fe are
poorly correlated with Vinj
Vinj > 600 km s-1
3He/4He > 2%
Conclusion: Injection Conclusion: Injection threshold speeds do not threshold speeds do not appear to play a appear to play a significant role in the significant role in the energy-dependent energy-dependent behavior of Fe/Obehavior of Fe/O
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
FeFe vs. O spectral index & O fluence vs. O spectral index & O fluenceFeFe vs. O spectral index & O fluence vs. O spectral index & O fluence
0 1 2 3 4
Oxygen Spectral Index(0.1-0.5 MeV n-1)
101 102 103 104 105 106 107
Oxygen Fluence (#/cm2 sr MeV n-1)(0.5-2.0 MeV n-1)
1.0
0.2
0.4
0.6
0.8
2.0
3.0
4.0
1.0
0.2
0.4
0.6
0.8
2.0
3.0
4.0
N= 68;r=0.58; p = 2.4 x10-5%
m = 0.39 ± 0.05
c =-0.94 ± 0.26
N= 61;r=-0.46; p =2.0 x10-2%
m = -0.09 ± 0.02
c = 1.81 ± 0.78
(a) (b)
Fe/O at IP shocks vs. ambientFe/O at IP shocks vs. ambientFe/O at IP shocks vs. ambientFe/O at IP shocks vs. ambient
10-2
10-1
100
Fe/O (Upstream)10-2 10-1 100
log(Fe/OShock) = c + m*log(Fe/OUpstream)
cu2 =0.53; =1.0P
=62; =0.51; =1.0 10N r p x -5
= 0.40 m ± 0.02 = 0.26 c ± 0.05
#29event
(Desai et al. 2003 ApJ, 588, 1149).
Fe/O ratios at IP Fe/O ratios at IP
shocks and ambient shocks and ambient
are well correlatedare well correlated
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
Shock C/O & Fe/O normalized to ambient Shock C/O & Fe/O normalized to ambient values values
Shock C/O & Fe/O normalized to ambient Shock C/O & Fe/O normalized to ambient values values
• Fe/O ratios are depleted by ~30% relative to ambient values
• Energy-dependence of Fe/O is diminished when compared with ambient Fe/O - not expected from mono-energetic injection
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
O Spectral index & Fe/O O Spectral index & Fe/O dependence at IP shocks vs. dependence at IP shocks vs.
Ambient Ambient
O Spectral index & Fe/O O Spectral index & Fe/O dependence at IP shocks vs. dependence at IP shocks vs.
Ambient Ambient
SummarySummarySummarySummary
• Spectral parameters and energy-dependence of Fe/O are independent of local shock parameters
• 5 out of 72 events (~7%) have rising Fe/O with energy; Fe/O in other events are constant or decrease with energy
• Fe/O at IP shocks are typically ~30% lower than in the ambient population
• The O spectra and energy-dependence of Fe/O are similar at IP shocks and in the ambient population
(Desai et al. To appear in ApJ.Aug. 20, 2004 issue)
Sketch of Re-acceleration of Seed spectra at IP Sketch of Re-acceleration of Seed spectra at IP shocks shocks
Sketch of Re-acceleration of Seed spectra at IP Sketch of Re-acceleration of Seed spectra at IP shocks shocks
10-1 100 101
Kinetic Energy (MeV n -1)
10-5
10-3
10-1
100
103
OFe
Seed SpectraShock Spectra
ConclusionConclusionConclusionConclusion
IP shocks accelerate seed spectra composed of
suprathermal ions from gradual and impulsive SEP
events by a systematic rigidity-dependent mechanism
where ions with higher M/Q are accelerated less
efficiently than those with lower M/Q
Relevant IssuesRelevant IssuesRelevant IssuesRelevant Issues
• How common are IP shock events with rising Fe/O ratios? ~7% of events have rising Fe/O with energy
• What are the key differences between IP shocks with rising and decreasing Fe/O ratios? No appreciable differences in shock properties
• Does any particular local shock parameter play a role in determining the energy-dependent behavior of Fe/O? Cannot rule this out completely, but no
evidence that local shock properties are important
• The primary cause of rising Fe/O in IP shocks Re-acceleration of energetic ion seed spectra
that themselves have rising Fe/O with energy