After extraction, all spectra were rebinned requiring a minimum of 20 and 30 counts per bin and selecting energy channels in the ranges 0.7 < E < 10 keV and 0.5 < E < 10 keV for the GIS and SIS spectra respectively. We fitted a Raymond-Smith spectrum attenuated by photoelectric absorption from the Galaxy, the only fixed parameter being the cluster redshifts. However, to allow for uncertainties in the calibration of the different instruments, the normalizing constants were fitted independently for each instrument. The spectra are presented in Figs. 3 and 4 and results from the spectral fitting summarized in Table 4.
|Figure 3: Upper panel: Individual SIS0, SIS1, GIS2, GIS3 and PSPC spectra of A 1300, together with the best fitting model. Lower panel: Residual (observed - fitted) spectrum|
|Figure 4: Upper panel: Individual SIS0, SIS1, GIS2 and GIS3 spectra of A 1732, together with the best fitting model. Lower panel: Residual (observed - fitted) spectrum|
The hydrogen column density is poorly constrained by the ASCA detectors in the low energy range. However, when the PSPC data for A 1300 are added in, the agreement with the radio measurement is excellent.
Luminosities (Table 4)
were calculated by circular integration on the GIS images within a
radius of corresponding to 2.8 Mpc for A 1300 and 2.1 Mpc for
A 1732. We used temperatures and abundances determined from the spectral
analysis whereas was fixed at its radio value. The agreement
with the ROSAT measurements (Table 2) is excellent for
A 1732. For A 1300, the PSPC measurement is about 15% lower than the ASCA
one; this can be readily understood as the PSPC luminosity has been
calculated from the fitted King profile, whereas the ASCA luminosity,
obtained by simple circular integration, is probably contaminated by unresolved point sources conspicuous in the PSPC image.
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