paper

Detecting Intracluster Gas Motion in Galaxy Clusters: Mock Astro-E2 Observations

arXiv:astro-ph/0503281 · doi:10.1086/432608

Abstract

We explore the detectability of bulk motions in the X-ray emitting intracluster medium (ICM) using a catalog of 1,836 mock Astro-E2 observations of simulated clusters of galaxies. We generate high resolution mock spectra for two observing strategies: a four-pointing mosaic and a single central pointing. Normalizing to 200 (400) photons in the iron K-alpha region for the mosaic (central) study, we fit Poisson realizations of each simulated spectrum to a velocity broadened isothermal plasma emission model. We confirm that the velocity characteristics (mean and dispersion) returned by the spectral fittings are unbiased measures of the emission-weighted values within the observed region, with scatter 55 km/s. The maximum velocity difference between mosaic element pairs has ~ 6% likelihood of being transonic (), and the likelihood falls steeply, $p \spropto (Δv_{\rm max}/c_s)^{-4}$, at high Mach number. The velocity broadening parameter from the central pointing fit exceeds the thermal value in 49% of the cases, with again a tail at large dispersion. We present as case studies the clusters that yield the strongest signal for each observing strategy.

13 pages, 20 figures. Submitted to ApJ. Version with postscript figures embedded in the text available at http://www.umich.edu/~apawl/astroe2/. Version 2 includes changes in response to referee report and corrects an error in optical depth estimates

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