Biases in Spectral Fits of Unresolved Non-Isothermal X-ray Clusters and Groups of Galaxies
Abstract
Using simulated spectra, we estimate the biases in the parameters describing the intra-cluster plasma, as obtained from spectral fits of spatially unresolved, polytropic non-isothermal X-ray clusters and group s of galaxies for various spectro-imaging instruments on X-ray telescopes (with an emphasis on XMM-Newton). We find that for typical observational parameters, the temperature obtained from single-temperature fits is equal, within simeq 10% to the emission-weighted temperature, but underestimated but up to 20% when a cooling flow is present (high temperature clusters). These results are little affected by the metal abundance of the plasma, the signal-to-noise ratio of the observations (above some minimum, rarely reached by ROSAT/PSPC or Asca) and the spectral resolution of the instrument. Estimations of metal abundances and hydrogen absorptions are little biased , excepted in presence of a cooling flow. The residual of single temperature fits tend to be largest near 1keV and we suggest a chi2 analysis on grouped energy channels in the range 0.7 - 1.3 keV
- Publication:
-
Constructing the Universe with Clusters of Galaxies
- Pub Date:
- 2000
- Bibcode:
- 2000cucg.confE..23M