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Using Multi-component Models

Example 1. 2-temperature plasma model 

*** PIMMS version 4.11 ***
    2020 Feb 27th Release
    Reading mission directory, please wait
* Current model is BREMSSTRAHLUNG, kT=  10.0000 keV; NH =  1.000E+21
   <--- Use 'MODEL' command to change
        and 'PLASMA' command to switch among APEC/mekal/RS
* By default, input rate is taken to be
 Flux (      2.000-     10.000 keV) in ergs/cm/cm/s
   <--- Use 'FROM' command to change the default
* Simulation product will be
 Count rate in CHANDRA ACIS-I
   <--- Use 'INSTRUMENT' command to switch to another instrument
PIMMS > mo plasma 6.6 logt 1.0 3e19 plasma 7.2 logt 1.0 3e19 0.5 1.0
PIMMS > output apec2t 0.1 4.0 0.002
PIMMS > inst rosat pspc open
PIMMS > from flux ergs 0.1-2.0 u
PIMMS > go 3e-11
* For PLASMA (APEC) model with
                        kT= 0.3431keV (logT= 6.60), Abund=1.0; NH =  3.000E+19
    + PLASMA (APEC) model with
                        kT= 1.3657keV (logT= 7.20), Abund=1.0; NH =  3.000E+19
             (  0.5000 times component 1 at     1.0000 keV)
   and an unabsorbed flux (    0.100-    2.000keV) of  3.000E-11 ergs/cm/cm/s
  (Internal model normalization =  1.474E-02)
* PIMMS predicts  3.987E+00 cps with ROSAT PSPC OPEN
PIMMS> quit

This first example illustrates the use of two-temperature plasma model. The absorption columns (to be specified explicitly for each component) are the same in this example. The second component has a flux at 1 keV which is 50% of the first component. Note, however, this is a tricky proposition for the line-rich plasma. It is best to check this via the output command, which allows the users to check the actual model spectrum.

Example 2. Partial covering absorber 

*** PIMMS version 4.11 ***
    2020 Feb 27th Release
    Reading mission directory, please wait
* Current model is BREMSSTRAHLUNG, kT=  10.0000 keV; NH =  1.000E+21
   <--- Use 'MODEL' command to change
        and 'PLASMA' command to switch among APEC/mekal/RS
* By default, input rate is taken to be
 Flux (      2.000-     10.000 keV) in ergs/cm/cm/s
   <--- Use 'FROM' command to change the default
* Simulation product will be
 Count rate in CHANDRA ACIS-I
   <--- Use 'INSTRUMENT' command to switch to another instrument
PIMMS > mo brems 15 3e23 brems 15 1e20 0.1 10 ga 6.5 0.1 250
PIMMS > output partial 0.1 10.0 0.005
PIMMS > inst xmm pn thin
PIMMS > go 0.5 asca sis
* For thermal Bremsstrahlung model with kT= 15.0000 keV; NH =  3.000E+23
    + thermal Bremsstrahlung model with kT= 15.0000 keV; NH =  1.000E+20
             (  0.1000 times component 1 at    10.0000 keV)
    + Gaussian model with E=  6.5000 keV; sigma= 0.1000 keV; NH =  3.000E+23
                          (Eq.W=250.0000 eV)
  and  5.000E-01 cps in ASCA SIS
%!% Integration over the entire chip (not just in the source region) assumed
  (Internal model normalization =  9.009E-03)
* PIMMS predicts  6.462E+00 cps with XMM PN THIN
  for on-axis observation, PATTERN=0-4, before dead time correction
  and assuming a 5 arcmin extraction radius enclosing ~100% of the PSF
  (The count rate within a more reasonable point source extraction region
   of ~15 arcsec radius would be roughly ~70% of this value)
WARNING: The pile-up estimate is approximate

% Pile-up and dead-time corrected count rates in 4 energy bands
  using various allowed window options are:

 Window    Pileup  Dead                Corrected Good Count Rates
   Option   frac.   Time    0.1-0.4   0.4-1.0   1.0-2.5  2.5-10.0     Total

 Full      7.883%   7.0%     0.5357    0.9250    1.0405    2.7705      5.5363
 FullExtd    >10%   7.0%     0.4295    0.7417    0.8343    2.2216      4.4394 ?
 Large     5.190%   9.0%     0.5395    0.9315    1.0479    2.7901      5.5756
 Small     0.482%  29.0%     0.4418    0.7629    0.8582    2.2850      4.5662

% Timing and Burst options are now only available for pn with the thick filter

% Any pile-up predictions over 10% are highly uncertain

PIMMS> quit
This example shows how to set up a spectrum suffering from partial covering absorption. In addition, a Gaussian is added which has a different syntax: the three parameters are the line energy (keV), the physical width (keV), and the equivalent width (eV). Absorbing column is assumed to be the same as the first component (it can be specified explicitly, as the third parameter before the equivalent width).

Example 3. A redshifte example 

*** PIMMS version 4.11 ***
    2020 Feb 27th Release
    Reading mission directory, please wait
* Current model is BREMSSTRAHLUNG, kT=  10.0000 keV; NH =  1.000E+21
   <--- Use 'MODEL' command to change
        and 'PLASMA' command to switch among APEC/mekal/RS
* By default, input rate is taken to be
 Flux (      2.000-     10.000 keV) in ergs/cm/cm/s
   <--- Use 'FROM' command to change the default
* Simulation product will be
 Count rate in CHANDRA ACIS-I
   <--- Use 'INSTRUMENT' command to switch to another instrument
PIMMS > mo pl 1.7 3e23 ga 6.4 0.2 150 plasma 1.2 1.0 0.0 1.0 2.5 z 0.01 8e19
NOTE: This version of PIMMS has a grid of  59x 5 grid of APEC models
      from kT= 0.034 keV (logT= 5.60) to kT=27.250 keV (logT= 8.50)
      and abundances from 0.20 to 1.00
         Selected temperature is  1.217 keV (log T is  7.15)
         and selected abundance is 1.0
PIMMS > output agn_sb 0.1 10.0 0.01
PIMMS > inst chandra acis-s
PIMMS > go 1e-11
* For power law model with photon index = 1.7000; NH =  3.000E+23
    + Gaussian model with E=  6.4000 keV; sigma= 0.2000 keV; NH =  3.000E+23
                          (Eq.W=150.0000 eV)
    + PLASMA (APEC) model with
                        kT= 1.2172keV (logT= 7.15), Abund=1.0; NH =  0.000E+00
             (  1.0000 times component 1 at     2.5000 keV)
 ...redshifted with z=  0.0100 and a Galactic Nh= 8.000E+19
   and a flux (      2.000-     10.000keV) of  1.000E-11 ergs/cm/cm/s
  (Internal model normalization =  5.883E-03)
* PIMMS predicts  2.000E-01 cps with CHANDRA ACIS-S
% Pileup estimate for ACIS:
  Pile-up is generally tolerable (10.0 %) at a frame-time of  1.324 s
PIMMS > quit
In this example, the entire composite model is to be redshifted with z=0.01. Absorption specified with each component is taken to be intrinsic (i.e., also redshifted). Additionally, a Galactic (unredshifted) absorption is specified. For "unabsorbed" flux, both intrinsic and Galactic absorption will temporarily be set to 0.
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This file was last modified on Wednesday, 14-May-2025 11:55:19 EDT