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
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 difference
WHAT IS THE “BEST”ELECTRON SPECTRUM
CORRESPONDING TO A GIVENPHOTON SPECTRUM?
Gordon Emslie
University of Alabama, Huntsville
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
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
Photon Fits and ResidualsRegularized Method; =2.45
Photon Fits and ResidualsThermal plus Double-Power-Law Forward Fit
Residuals - Matrix Inversion
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)
Smoothing the residuals
Smoothing the residuals
Results Comparison: 23 July 2003, 00:30:00 - 00:30:20
• White: Johns & Lin (1992)
• Red: Piana et al. 0th order regularization
Pileup Corrections:
Pileup Corrections:Pileup Corrections:
Note: not fully consistent as forward fit was not done to corrected photon spectrum
Effects of Albedo II:
Following Bai and Ramaty (1978)
No albedo correction
With albedo correction
Johns & Lin (1992) Cross Sections
• Koch & Motz 1959, Rev. Modern Physics, 31, 920
• See also erratum to Johns & Lin 1992, Sol. Phys., 142, 219
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
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
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
fit- = -0.30.4 [Eobs1,Eobs2] [10,100] E [5,125] [2.0,8.0]
Effects of Albedo and Non-constant Ionization Structure
„Kink“ model:
73, th
STDKIN
E
E
„Cutoff“ model:
35.1, th
STDKIN
E
E
Effects of Albedo and Non-constant Ionization Structure
Vilmer et al.
White: RHESSI 25-50 keV Hard X-rays
Black: RHESSI 12-25 keV Soft X-rays
NRH 327 MHzduring 4 burstsBetween 131120 and 131140
RHESSI25-50 keV