Mon. Not. R. Astron. Soc., 422, 3503-3515 (2012/June-1)
X-ray observations of the galaxy cluster Abell 2029 to the virial radius.
WALKER S.A., FABIAN A.C., SANDERS J.S., GEORGE M.R. and TAWARA Y.
Abstract (from CDS):
We present Suzaku observations of the galaxy cluster Abell 2029, which exploit Suzaku's low particle background to probe the intracluster medium at radii beyond that which is possible with previous observations, and with better azimuthal coverage. We find significant anisotropies in the temperature and entropy profiles, with a region of lower temperature and entropy occurring to the south-east, possibly the result of accretion activity in this direction. Away from this cold feature, the thermodynamic properties are consistent with an entropy profile which rises, but less steeply than the predictions of purely gravitational hierarchical structure formation. Excess emission in the northern direction can be explained due to the overlap of the emission from the outskirts of Abell 2029 and nearby Abell 2033 (which is at slightly higher redshift). These observations suggest that the assumptions of spherical symmetry and hydrostatic equilibrium break down in the outskirts of galaxy clusters, which poses challenges for modelling cluster masses at large radii and presents opportunities for studying the formation and accretion history of clusters.
2012 The Author Monthly Notices of the Royal Astronomical Society2012 RAS