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

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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