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Problem #1. MOS spectral redistribution function has evolved temporarily and spatially whilst in orbit. We do not have an accurate physical description of the effect which can be used to model the observed changes. Solution #1. - PowerPoint PPT Presentation
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XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
MOS spectral redistribution function has evolved temporarily and spatially
whilst in orbit. We do not have an accurate physical description of the effect
which can be used to model the observed changes.
Problem #1
Observations of astronomical objects with known spectral parameters can
be used analytically to adjust the parameters of the rmf for all
detector/epoch/region/pattern combinations.
Solution #1
Problem #2
Extremely time consuming as this is largely a manual process requiring analysis of
potentially hundreds of spectral fits to fully characterise the rmf evolution.
Automated Spectral Response FittingSolution #2
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
function myfunct, p ; p(n)
newccf = rmf_param_adjust(p, oldccf)
rmf = rmfgen(newccf)
chisq = xspec_fit(spectrum, model, rmf)
return, chisq
end
pro rmfmin, p, chimin
result = tnmin(‘myfunct’, p, bestmin=chimin, /autoderivative)
newccf = rmf_param_adjust(result, oldccf)
return
end
E = 1.49 keV
model ga σ = 0.0
N = free
σnew(1.49) = p x σold(1.49)
Code development by Jenny
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
;+ ; NAME: ; TNMIN ; ; AUTHOR: ; Craig B. Markwardt, NASA/GSFC Code 662, Greenbelt, MD 20770 ; [email protected] ; UPDATED VERSIONs can be found on my WEB PAGE: ; http://cow.physics.wisc.edu/~craigm/idl/idl.html; ; PURPOSE: ; Performs function minimization (Truncated-Newton Method) ; ; MAJOR TOPICS: ; Optimization and Minimization ;; CALLING SEQUENCE:; parms = TNMIN(MYFUNCT, X, FUNCTARGS=fcnargs, NFEV=nfev, ; MAXITER=maxiter, ERRMSG=errmsg, NPRINT=nprint, ; QUIET=quiet, XTOL=xtol, STATUS=status,; FGUESS=fguess, PARINFO=parinfo, BESTMIN=bestmin, ; ITERPROC=iterproc, ITERARGS=iterargs, niter=niter) ;; DESCRIPTION:; ; TNMIN uses the Truncated-Newton method to minimize an arbitrary IDL ; function with respect to a given set of free parameters. Blah…….
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
function myfunct, p ; p(n)
newccf = rmf_param_adjust(p, oldccf)
rmf = rmfgen(newccf)
chisq = xspec_fit(spectrum, model, rmf)
return, chisq
end
pro rmfmin, p, chimin
result = tnmin(‘myfunct’, p, bestmin=chimin, /autoderivative)
newccf = rmf_param_adjust(result, oldccf)
return
end
Slow ~ secs to mins
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Results from 3 sets of tests:
1) Fitting the Al calibration line(s) at epoch Rev 110-169
2) Fitting the low energy continuum of 3C273 at epoch 0-109
3) Fitting the continuum of RXJ1856 at epoch 744+
Mono-pixel spectra used throughout
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #1: Resolution at Al Kα
“Red” wing is due to incomplete charge collection rather than intrinsic broadening
Al Kα = Kα1(1.4867) + 0.5 x Kα2(1.4863)
In our analytic rmf model we model this by splitting the profile
“Red” side = Gaussian(σ) + Gaussian(R x σ)
“Blue” side = Gaussian(σ)
Normalisations
match at join
In our automatic fitting we adjust the values of σ (~30) and
R (~1.5) at 1.487 keV by “fudge” factors, p, such that
σnew = p1 x σold
Rnew = p2 x Rold
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
E = 1.5574, σ = 0.0, N = 0.01N0
Spectral Model: (ga + ga + ga) Fit Range: 1.4-1.56 keV
Test #1: Resolution at Al Kα
E = 1.4863, σ = 0.0, N = 0.5N0
E = 1.4867, σ = 0.0, N0 = free
P1 = 1.0
P2 = 1.0
Χ2ν = 18.4
P1 = 1.047
P2 = 0.894
Χ2ν = 7.74
Proc. Time = 1.72 hrs
α1
α2
β1
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #1: Resolution at Al Kα
MOS1 Mg XI line in Zeta Puppis, Rev 0156, RGS Model
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
MOS1 ratio imageEnergy
Epoch
TU Mode
TU Mode
Test #2: Low energy continuum of 3C 273 (Rev 0094)Continuum (“hard power law + soft excess”) fits to 3c 273
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #2: Low energy continuum of 3C 273 (Rev 0094)
1.0
0.0
f(d)
d
f(d) = α + βd d < d0
= 1.0 d ≥ d0
d0
α
Eobs(d) = Ein(d) x f(d)
Integrate over d to get profile α
β
Surface Loss Function
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #2: Low energy continuum of 3C 273 (Rev 0094)
Alpha Parameter v Energy, Epoch Rev 0-109
Fudge factor defined at 350, 500, 650 eV
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #2: Low energy continuum of 3C 273 (Rev 0094)
nH = 1.79 x 1020 cm-2
Γ = 1.644, N0 = 0.0194
Γ = Free, N0 = Free
Spectral Model: phabs * (po + po) Fit Range: 0.1-1.0 keV
Rev 0094
Χ2ν = 3.01 Χ2
ν = 1.97
Proc. Time: 3.9 Hrs
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #2: Low energy continuum of 3C 273 (Rev 0094)
Alpha Parameter v Energy, Epoch Rev 0-109
Fudge factor defined at 350, 500, 650 eV
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Fit model to PN and fold through MOS1 (old and new rmf)
Test #2: Low energy continuum of 3C 273 (Rev 0094)
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
RGS model (renormalised) fit to MOS1 in 0.1-0.55 keV band
Test #2: Low energy continuum of 3C 273 (Rev 0094)
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #3: BB fits to RXJ1856 (Rev 0798)
MOS1 Core
nH = 1.4(0.1)E20
kT = 61.4(0.2) eV
MOS1 Wings
nH = 1.1(0.2)E20
kT = 60.3(0.4) eV
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #3: BB fits to RXJ1856 (Rev 0798)
MOS2 Core
nH = 0.93(0.1)E20
kT = 62.0(0.3) eV
MOS2 Wings
nH = 0.98(0.2)E20
kT = 59.7(0.5) eV
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #3: BB fits to RXJ1856 (Rev 0798)
nH = 0.75 x 1020 cm-2
kT = 62 eV, N0 = Free
Spectral Model: phabs * bb Fit Range: 0.1-1.0 keV
Fudge Factors:
alpha surface loss parameters at…..250, 350, 450, 550 eV
Parameters reported by Vadim/Frank
for pn at previous Cal. meeting
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #3: BB fits to RXJ1856 (Rev 0798)
Fit to MOS1 data with new rmf
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #3: BB fits to RXJ1856 (Rev 0798)
Fit to MOS2 data with new rmf
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #3: BB fits to RXJ1856 (Rev 0798)
Fit to MOS1 3c 273 data with old/new rmf
nH = 2.6(0.2)e20 cm-2
nH = 2.1(0.2)e20 cm-2
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #3: BB fits to RXJ1856 (Rev 0798)
Fit to MOS2 3c 273 data with old/new rmf
nH = 2.4(0.2)e20 cm-2
nH = 1.9(0.2)e20 cm-2
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Conclusions
• Algorithm works!
• Timely results can be gained even using a single
CPU, but we intend to port code to the multi(250) processor
central computing facility at Leicester
• Smoothing out the residuals in early MOS 3c 273 data
improves cross-calibration with pn and probably rgs
• Forcing spectral agreement between MOS and pn in
RXJ1856 improves residuals in contemporary
MOS2 3c 273 data
XMMEPICMOS
Steve Sembay ([email protected])Mallorca 26/10/06
Test #2: Low energy continuum of 3C 273