Statistical Uncertainties in Temperature Diagnostics for Hot Coronal Plasma Using the ASCA SIS
Abstract
Statistical uncertainties in determining the temperatures of hot (0.5 keV to 10 keV) coronal plasmas are investigated. The statistical precision of various spectral temperature diagnostics is established by analyzing synthetic ASCA Solidstate Imaging Spectrometer (SIS) CCD spectra. The diagnostics considered are the ratio of hydrogenlike to heliumlike line complexes of $Z\ge14$ elements, linefree portions of the continuum, and the entire spectrum. While fits to the entire spectrum yield the highest statistical precision, it is argued that fits to the linefree continuum are less susceptible to atomic data uncertainties but lead to a modest increase in statistical uncertainty over full spectral fits. Temperatures deduced from line ratios can have similar accuracy but only over a narrow range of temperatures. Convenient estimates of statistical accuracies for the various temperature diagnostics are provided which may be used in planning ASCA SIS observations.
 Publication:

The Astrophysical Journal
 Pub Date:
 November 1994
 DOI:
 10.1086/187616
 arXiv:
 arXiv:astroph/9408101
 Bibcode:
 1994ApJ...435L.149S
 Keywords:

 Galactic Clusters;
 Line Spectra;
 Plasma Temperature;
 Space Plasmas;
 Statistical Correlation;
 Stellar Coronas;
 Charge Coupled Devices;
 Data Reduction;
 Helium;
 Hydrogen;
 Ionization;
 SatelliteBorne Instruments;
 Statistical Analysis;
 Temperature Distribution;
 X Ray Telescopes;
 Astrophysics;
 METHODS: DATA ANALYSIS;
 XRAYS: GENERAL;
 GALAXIES: CLUSTERING;
 Astrophysics
 EPrint:
 postscript file of 8 pages+3 figures