SPEX User's Manual - SRON

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20 Syntax overview dem gene #i1 #i2 - Do DEM analysis using the genetic algorithm, using a population size given by #i1 (maximum value 1024) and #i2 is the number of generations (no limit, in practice after ∼100 generations not much change in the solution. Experiment with these numbers for your practical case. dem read #a - Read a DEM distribution from a file named #a which automatically gets the extension ”.dem”. It is an ascii file with at least two columns, the first column is the temperature in keV and the second column the differential emission measure, in units of 10 64 m −3 keV −1 . The maximum number of data points in this file is 8192. Temperature should be in increasing order. The data will be interpolated to match the temperature grid defined in the dem model (which is set by the user). dem save #a - Save the DEM to a file #a with extension ”.dem”. The same format as above is used for the file. A third column has the corresponding error bars on the DEM as determined by the DEM method used (not always relevant or well defined, exept for the regularization method). dem smooth #r - Smoothes a DEM previously determined by any DEM method using a block filter/ Here #r is the full width of the filter expressed in 10 log T. Note that this smoothing will in principle worsen the χ 2 of the solution, but it is sometimes useful to ”wash out” some residual noise in the DEM distribution, preserving total emission measure. Examples dem lib - create the DEM library dem reg auto - use the automatic regularization method dem reg 10. - use a regularization parameter of R = 10 in the regularization method dem chireg 1.e-5 1.e5 11 - do a grid search using 11 regularisation parameters R given by 10 −5 , 10 −4 , 0.001, 0.01, 0.1, 1, 10, 100, 1000, 10 4 , 10 5 . dem clean - use the clean method dem poly 7 - use a 7th degree polynomial method dem gene 512 128 - use the genetic algorithm with a population of 512 and 128 generations dem save mydem - save the current dem on a file named mydem.dem dem read modeldem - read the dem from a file named modeldem.dem dem smooth 0.3 - smooth the DEM to a temperature width of 0.3 in 10 log T (approximately a factor of 2 in temperature range). 2.8 Distance: set the source distance Overview One of the main principles of SPEX is that spectral models are in principle calculated at the location of the X-ray source. Once the spectrum has been evaluated, the flux received at Earth can be calculated. In order to do that, the distance of the source must be set. SPEX allows for the simultaneous analysis of multiple sky sectors. In each sector, a different spectral model might be set up, including a different distance. For example, a foreground object that coincides partially with the primary X-ray source has a different distance value. The user can specify the distance in a number of different units. Allowed distance units are shown in the table below.
2.8 Distance: set the source distance 21 Abbrevation spex m au ly pc kpc mpc z cz Table 2.3: SPEX distance units Unit internal SPEX units of 10 22 m (this is the default) meter Astronomical Unit, 1.49597892 10 11 m lightyear, 9.46073047 10 15 m parsec, 3.085678 10 16 m kpc, kiloparsec, 3.085678 10 19 m Mpc, Megaparsec, 3.085678 10 22 m redshift units for the given cosmological parameters recession velocity in km/s for the given cosmological parameters The default unit of 10 22 m is internally used in all calculations in SPEX. The reason is that with this scaling all calculations ranging from solar flares to clusters of galaxies can be done with single precision arithmetic, without causing underflow or overflow. For the last two units (z and cz), it is necessary to specify a cosmological model. Currently this model is simply described by H 0 , Ω m (matter density), Ω Λ (cosmological constant related density), and Ω r (radiation density). At startup, the values are: H 0 : 70 km/s/Mpc , Ω m : 0.3 , Ω Λ : 0.7 , Ω r : 0.0 i.e. a flat model with cosmological constant. However, the user can specify other values of the cosmological parameters. Note that the distance is in this case the luminosity distance. Note that the previous defaults for SPEX (H 0 = 50, q 0 = 0.5) can be obtained by putting H 0 = 50, Ω m = 1, Ω Λ = 0 and Ω r = 0. Warning: when H 0 or any of the Ω is changed, the luminosity distance will not change, but the equivalent redshift of the source is adjusted. For example, setting the distance first to z=1 with the default H 0 =70 km/s/Mpc results into a distance of 2.03910 26 m. When H 0 is then changed to 100 km/s/Mpc, the distance is still 2.16810 26 m, but the redshift is adjusted to 1.3342. Warning: In the output also the light travel time is given. This should not be confused with the (luminosity) distance in light years, which is simply calculated from the luminosity distance in m! Syntax The following syntax rules apply to setting the distance: distance [sector #i:] #r [#a] - set the distance to the value #r in the unit #a. This optional distance unit may be omittted. In that case it is assumed that the distance unit is the default SPEX unit of 10 22 m. The distance is set for the sky sector range #i:. When the optional sector range is omitted, the distance is set for all sectors. distance show - displays the distance in various units for all sectors. distance h0 #r - sets the Hubble constant H 0 to the value #r.
Page 1: SPEX User’s Manual Jelle Kaastra
Page 4 and 5: 4 CONTENTS 2.29 System . . . . . .
Page 6 and 7: 6 CONTENTS 5.8.3 ASCA SIS0 . . . .
Page 8 and 9: 8 Introduction 1.2.2 Sky sectors Fi
Page 10 and 11: 10 Introduction
Page 12 and 13: 12 Syntax overview Table 2.2: Abund
Page 14 and 15: 14 Syntax overview tcl: the continu
Page 16 and 17: 16 Syntax overview Examples calc -
Page 18 and 19: 18 Syntax overview by averaging the
Page 22 and 23: 22 Syntax overview distance om #r -
Page 24 and 25: 24 Syntax overview Examples elim 0.
Page 26 and 27: 26 Syntax overview This is strictly
Page 28 and 29: 28 Syntax overview Currently these
Page 30 and 31: 30 Syntax overview Syntax The follo
Page 32 and 33: 32 Syntax overview status, range an
Page 34 and 35: 34 Syntax overview par write mypar
Page 36 and 37: 36 Syntax overview plot box col #i
Page 38 and 39: 38 Syntax overview plot type data -
Page 40 and 41: 40 Syntax overview 2.26 Simulate: S
Page 42 and 43: 42 Syntax overview step axis 2 par
Page 44 and 45: 44 Syntax overview Examples use 100
Page 46 and 47: 46 Syntax overview width. On top of
Page 48 and 49: 48 Syntax overview
Page 50 and 51: 50 Spectral Models acronym pow delt
Page 52 and 53: 52 Spectral Models Finally, we have
Page 54 and 55: 54 Spectral Models where Q is the l
Page 56 and 57: 56 Spectral Models 3. set=3: for R
Page 58 and 59: 58 Spectral Models 3.14 Hot: collis
Page 60 and 61: 60 Spectral Models can be transform
Page 62 and 63: 62 Spectral Models The emission mea
Page 64 and 65: 64 Spectral Models 3.23 Refl: Refle
Page 66 and 67: 66 Spectral Models • type=3: b 1
Page 68 and 69: 68 Spectral Models 4.8, 4.9, 5.0 wi
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70 More about plotting Table 4.1: A
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72 More about plotting 4.4 Plot lin
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74 More about plotting Table 4.2: A
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76 More about plotting 4.6 Plot cap
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78 More about plotting 4.8 Plot axi
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80 More about plotting bin cou cs k
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82 More about plotting
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84 Response matrices models. Since
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86 Response matrices Table 5.1: Wei
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88 Response matrices Table 5.2: Sca
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90 Response matrices since the larg
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92 Response matrices Figure 5.1: Di
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94 Response matrices for the Cauchy
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96 Response matrices bin j of this
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98 Response matrices The approximat
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100 Response matrices particular bi
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102 Response matrices reduced by ab
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104 Response matrices where as befo
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106 Response matrices 5. Determine
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108 Response matrices practical pro
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110 Response matrices Table 5.10: T
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112 Response matrices Table 5.11: F
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114 Response matrices Figure 5.7: B
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116 Response matrices Table 5.15: R
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118 Response matrices
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120 Installation and testing
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122 Acknowledgements
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124 BIBLIOGRAPHY [2003] Peterson, J
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SPEX User's Manual - SRON

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