Issue |
A&A
Volume 446, Number 2, February I 2006
|
|
---|---|---|
Page(s) | 429 - 438 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20054025 | |
Published online | 13 January 2006 |
Structure and scaling of the entropy in nearby galaxy clusters
1
MPE Garching, Giessenbachstraße, 85748 Garching, Germany e-mail: gwp@mpe.mpg.de
2
CEA/Saclay, Service d'Astrophysique, L'Orme des Merisiers, Bât. 709, 91191 Gif-sur-Yvette Cedex, France
3
Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
Received:
10
August
2005
Accepted:
22
September
2005
Using XMM-Newton observations, we investigate the
scaling and structural properties of the ICM entropy in a sample of 10 nearby ()
morphologically relaxed galaxy clusters in the temperature range 2-9 keV. We derive the local entropy-temperature (
) relation at
and
. The logarithmic slope of the relation is
the same within the
error at all scaled radii. However, the
intrinsic dispersion about the best fitting relation is significantly
higher at
. The slope is
at
, in
excellent agreement with previous work. We also investigate the
entropy-mass relation at density contrasts
and
1000. We find a shallower slope than that expected in simple
self-similar models, which is in agreement with the observed
empirically-determined entropy-temperature and mass-temperature
scaling. The dispersion is smaller than for the
relation.
Once scaled appropriately, the entropy profiles appear
similar beyond ~
, with an intrinsic dispersion of ~15 per cent and a shape consistent with
gravitational heating (
). However, the scatter
in scaled entropy profiles increases with smaller scaled radius, to
more than 60 per cent at
. Our results are in
qualitative agreement with models which boost entropy production at
the accretion shock. However, localised entropy modification may be needed
to explain the dispersion in the inner regions.
Key words: cosmology: observations / galaxies: intergalactic medium / X-rays / galaxies: clusters
© ESO, 2006
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