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Effects on a Thermal Spectrum


Here we show the effects of using OLD and CURRENT calibrations on a thermal type spectrum by using AO3 data for the cluster Abell 2597 (z=0.0821). Results for 0.5-10 keV spectral fits using a Raymond-Smith model plus absorption (at z=0). We see that the absorbing column, temperature, and metal abundance are all consistent, within the errors, when measured with the OLD or CURRENT calibration. Again, these are early data (June 1995), so are not significantly affected by the low-energy efficiency degradation of the SIS. The measured column density is about four times the Galactic value (which is 2.49e20 cm-2). Once again note that the GIS cannot measure column densities as small as ~1e21 cm-2.

Note the larger fluxes and temperatures measured by GIS2 and GIS3 compared with SIS0 and SIS1. This is because the GIS extraction regions (6 arcmin radius) are larger than those for the SIS (4 arcmin radius) and the cluster is extended. The ARF files were all made using the `extended source' option in ASCAARF.

Table 3

0.5-10 keV RAYMOND-SMITH Spectral Fits to Abell 2597 (AO3)

(0.8-10 keV for GIS)

Error ranges are for 90% confidence, 1 parameter

    Parameter

    OLD

    CURRENT

    SIS0:

    -

    -

    NH (1e20 cm^-2)

    13.2 [11.4-14.7]

    12.1 [10.5-13.7]

    kT (keV)

    2.99 [2.85-3.17]

    3.08 [2.93-3.24]

    Abundance

    0.20 [0.14-0.25]

    0.27 [0.20-0.34]

    0.5-10 keV flux [1e-12 ergs/cm/cm/s]

    11.5

    12.4

    2-10 keV flux [1e-12 ergs/cm/cm/s]

    6.3

    6.8

    Chi-Square (d.o.f.)

    216.5(147)

    203.3(148)

    SIS1:

    -

    -

    NH (1e20 cm^-2)

    10.5 [8.8-12.1]

    10.5 [8.8-12.1]

    kT (keV)

    3.26 [3.10-3.46]

    3.28 [3.12-3.47]

    Abundance

    0.25 [0.19-0.31]

    0.33 [0.24-0.42]

    0.5-10 keV flux [1e-12 ergs/cm/cm/s]

    11.7

    12.8

    2-10 keV flux [1e-12 ergs/cm/cm/s]

    6.5

    7.2

    Chi-Square (d.o.f.)

    157.9(143)

    169.9(144)

    GIS2:

    -

    -

    NH (1e20 cm^-2)

    2.1 [0.0-5.7]

    0.0 [0.0-4.1]

    kT(keV)

    3.41 [3.23-3.58]

    3.58 [3.39-3.72]

    Abundance

    0.31 [0.23-0.40]

    0.30 [0.22-0.38]

    0.5-10 keV flux [1e-12 ergs/cm/cm/s]

    21.7

    27.5

    2-10 keV flux [1e-12 ergs/cm/cm/s]

    11.2

    14.3

    Chi-Square (d.o.f.)

    380.1(338)

    372.5(338)

    GIS3:

    -

    -

    NH (1e20 cm^-2)

    1.9 [0.0-5.4]

    0.0 [0.0-1.8]

    kT(keV)

    3.42 [3.24-3.60]

    3.53 [3.40-3.64]

    Abundance

    0.27 [0.20-0.35]

    0.30 [0.23-0.37]

    0.5-10 keV flux [1e-12 ergs/cm/cm/s]

    22.9

    28.7

    2-10 keV flux [1e-12 ergs/cm/cm/s]

    11.9

    14.7

    Chi-Square (d.o.f.)

    366.5(343)

    368.8(343)


Previous: Effects on Power-Law Slope and Absorbing Column
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This file was last modified on Monday, 30-Jul-2001 18:17:25 EDT
Curator: Michael Arida (SP Sys); arida@milkyway.gsfc.nasa.gov
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This file was last modified on Monday, 30-Jul-2001 18:17:25 EDT

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