team ii summary
DESCRIPTION
Team II Summary. From Photons to Particles and Beyond RHESSI-NESSI: June 4-6, 2003. Motivation: 23 July 2003, 00:30:00 - 00:30:20. Solid: Holman et al. forward fit Boxes: Piana et al. 0th order regularization. 5.5 r difference. Qualities of a “good” electron spectrum. - PowerPoint PPT PresentationTRANSCRIPT
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Team II Summary
From Photons to Particles and Beyond
RHESSI-NESSI: June 4-6, 2003
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Motivation: 23 July 2003, 00:30:00 - 00:30:20
• Solid: Holman et al. forward fit
• Boxes: Piana et al. 0th order regularization
5.5 difference
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WHAT IS THE “BEST”ELECTRON SPECTRUM
CORRESPONDING TO A GIVENPHOTON SPECTRUM?
Gordon Emslie
University of Alabama, Huntsville
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Qualities of a “good” electron spectrum
• Must correspond to a “good” fit to the photon spectrum
• Should contain as little a priori “information” as possible consistent with what is known about the physics of the emission process
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Examples of “Information” in an F(E)form
• Forward-fit (Holman et al.)– Few parameters but much information
• Ratio of fluxes at all pairs of points with same energy ratio is constant
• Forward-fit to nonuniform ionization model (Kontar et al.)– One extra parameter (depth of transition region)
• Matrix Inversion (Johns & Lin)– No parameters but requires smoothing
• Regularized Inversion (Piana et al.)– Smoothing parameter and type of norm used in constraining
recovered solution
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Photon Fits and ResidualsRegularized Method; =2.45
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Photon Fits and ResidualsThermal plus Double-Power-Law Forward Fit
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Residuals - Matrix Inversion
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R_TEST results
• Number of positive (negative) residuals = N+ (N_)• Number (fraction) of runs = N_r (f_r)
• Negative Z implies more clustering (fewer “runs”) than expected byrandom chance
• Although fractional +/- split of residuals is very similar, forward-fitresiduals have a higher probability (1/6) of being random thanregularized residuals (1/10) or residuals from nonuniform ionization fit(1/1000)
• Very low number of runs for nonuniform ionization implies highdegree of residual clustering!
N N_ (f_) N+ (f+) N_r (f_r) E_r _r Z p
Regularized Inversion 146 69 (0.473) 77 (0.527) 66 (0.452) 74 6.0 -1.30 0.10Forward-Fit 70 37 (0.529) 33 (0.471) 32 (0.457) 36 4.1 -0.94 0.17Nonuniform Ionization 282 128 (0.454) 154 (0.546) 116 (0.411) 141 8.3 -2.98 0.001
(R_TEST is an IDL procedure)
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Smoothing the residuals
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Smoothing the residuals
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Results Comparison: 23 July 2003, 00:30:00 - 00:30:20
• White: Johns & Lin (1992)
• Red: Piana et al. 0th order regularization
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Pileup Corrections:
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Pileup Corrections:Pileup Corrections:
Note: not fully consistent as forward fit was not done to corrected photon spectrum
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Effects of Albedo II:
Following Bai and Ramaty (1978)
No albedo correction
With albedo correction
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Johns & Lin (1992) Cross Sections
• Koch & Motz 1959, Rev. Modern Physics, 31, 920
• See also erratum to Johns & Lin 1992, Sol. Phys., 142, 219
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Action Items:
• Re-write bremspec in SSW - most accurate cross-section, e-n, e-i, e-e
• Optimize binning of Johns & Lin and translate to IDL with user friendly interface in SSW
• Implement rectangular form of regularization
• Put regularized inversions in SSW
• Mote Carlo simulations to evaluate significance of clustering in fit residuals
• Analyze more sources and times
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PHASE SHIFTS OF ALBEDO PATCH? Single-SC back-projection maps vs energy band 2002 J uly 03
Note that the SC-9 maps shift with energy. Is thisa signature of albedo?
12-25
6-12
50-100
25-50
LIMB
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Exponential + Gaussian Fits vs. Energy
Note the increasing exponential component with increasing energy.
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Polarization ResultsPolarization ResultsX4.8 Flare, 23 July 2002, 00:26 - 00:42 UT
-2 0 0 0
-1 0 0 0
0
1 0 0 0
2 0 0 0
Co
un
ts
3 6 03 2 02 8 02 4 02 0 01 6 01 2 08 04 00
A zimu th al Scatter A n g le (d eg s)
2 3 Ju ly 2 0 0 2 , 0 0:2 6 - 0 0 :4 2 U T
M ea sured Po la riza tion C o mpo nent4 0 -6 0 keV
-2 0 0 0
-1 0 0 0
0
1 0 0 0
2 0 0 0
Co
un
ts
3 6 03 2 02 8 02 4 02 0 01 6 01 2 08 04 00
A zimu th al Scatter A n g le (d eg s)
2 3 Ju ly 2 0 0 2 , 0 0 :2 6 - 0 0:4 2 U T
M ea sured Po la riza tio n C o mpo nent6 0-8 0 keV
-2000
-1000
0
1000
2000
Co
un
ts
36032028024020016012080400
Azimuthal Scatter Angle (degs)
2 3 Ju ly 2 0 0 2 , 0 0 :2 6 - 0 0 :4 2 U T
M ea sured Po la riza tio n C o mpo nent8 0 -1 0 0 keV
10000
8000
6000
4000
2000
0
Co
unt
s
350300250200150100500
Azimuthal Scatter Angle (degs)
M ea sured Po la riza tio n C o mp o nent2 0 - 4 0 keV
2 3 Ju ly 2 0 0 2 , 0 0 :2 6 - 0 0 :4 2 U T
µP = 0.18±0.05
µ100 = 0.66
P = 27(±7)%
=(100,280)o
µP = 1.95±0.33
µ100 " 0.45
P = ?!?
=(110,290)o
µP = 0.90±0.26
µ100 " 0.35
P = ?!?
=(110,290)o
µP = 1.24±0.55
µ100 " 0.25
P = ?!?
=(90,270)o
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Polarization Direc tionPolarization Direc tion
RadialDirection
Polarizationdirection
Location of Flare
Polarizationdirection isalmosttransverse –perpendicularto radialdirection!
100o
Direction inconsistent with bulk motion on vertical magnetic fields, but is consistent with albedo contribution
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fit- = -0.30.4 [Eobs1,Eobs2] [10,100] E [5,125] [2.0,8.0]
Effects of Albedo and Non-constant Ionization Structure
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„Kink“ model:
73, th
STDKIN
E
E
„Cutoff“ model:
35.1, th
STDKIN
E
E
Effects of Albedo and Non-constant Ionization Structure
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Vilmer et al.
White: RHESSI 25-50 keV Hard X-rays
Black: RHESSI 12-25 keV Soft X-rays
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NRH 327 MHzduring 4 burstsBetween 131120 and 131140
RHESSI25-50 keV