Mon. Not. R. Astron. Soc., 449, 199-219 (2015/May-1)
Cosmology and astrophysics from relaxed galaxy clusters - I. Sample selection.
MANTZ A.B., ALLEN S.W., MORRIS R.G., SCHMIDT R.W., VON DER LINDEN A. and URBAN O.
Abstract (from CDS):
This is the first in a series of papers studying the astrophysics and cosmology of massive, dynamically relaxed galaxy clusters. Here we present a new, automated method for identifying relaxed clusters based on their morphologies in X-ray imaging data. While broadly similar to others in the literature, the morphological quantities that we measure are specifically designed to provide a fair basis for comparison across a range of data quality and cluster redshifts, to be robust against missing data due to point source masks and gaps between detectors, and to avoid strong assumptions about the cosmological background and cluster masses. Based on three morphological indicators - symmetry, peakiness, and alignment - we develop the symmetry-peakiness-alignment (SPA) criterion for relaxation. This analysis was applied to a large sample of cluster observations from the Chandra
archives. Of the 361 clusters which received the SPA treatment, 57 (16 per cent) were subsequently found to be relaxed according to our criterion. We compare our measurements to similar estimators in the literature, as well as projected ellipticity and other image measures, and comment on trends in the relaxed cluster fraction with redshift, temperature, and survey selection method. Code implementing our morphological analysis will be made available on the web (http://www.slac.stanford.edu/amantz/work/morph14/
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
galaxies: clusters: general - X-rays: galaxies: clusters
VizieR on-line data:
<Available at CDS (J/MNRAS/449/199): table1.dat tablea1.dat tablea2.dat>
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