| Issue |
A&A
Volume 414, Number 2, February I 2004
|
|
|---|---|---|
| Page(s) | 429 - 443 | |
| Section | Cosmology (including clusters of galaxies) | |
| DOI | https://doi.org/10.1051/0004-6361:20031662 | |
| Published online | 19 January 2004 | |
Temperature map computation for X-ray clusters of galaxies
1
Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
2
CEA/DSM/DAPNIA, Service d'Astrophysique, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
3
NIC Consortium (Numerical Investigations in Cosmology, CEA Saclay)
Corresponding author: H. Bourdin, bourdin@obs-nice.fr
Received:
16
April
2003
Accepted:
19
September
2003
Recent numerical simulations have
shown that the variations of the gas temperature in clusters of
galaxies are indicative of the dynamical state of these
clusters. Maps of the temperature variation show complex structures
with different shapes at different spatial scales, such as hot
compression regions, filaments, cooling flows, or large-scale
temperature profiles. A new multiscale spectro-imagery algorithm
for restoring the spatial temperature variations within clusters of
galaxies is presented here. It has been especially developed to work
with the EPIC MOS1, MOS2 and PN spectro-imagers on board the
XMM-Newton satellite. The temperature values are fitted to an emission
model that includes the source, the cosmic X-ray background and
cosmic-ray induced particle background. The spatial temperature
variations are coded at different scales in the wavelet space using
the Haar wavelet and denoised by thresholding the wavelet
coefficients. Our local temperature estimator behaves asymptotically
like an optimal mininum variance bound estimator. But it is highly
sensitive to the instrumental and astrophysical backgrounds, so that a
good knowledge of each component of the emission model is required.
Our algorithm has been applied to a simulated 60 ks observation of a
merging cluster at 
. The cluster at different stages of
merging has been provided by 3-D hydrodynamical simulations of
structure formation (AMR). The multiscale approach has enabled us to
restore the faint structures within the core of the merging subgroups
where the gas emissivity is high, but also the temperature decrease at
large scale in their external regions.
Key words: galaxies: clusters: general / galaxies: interactions
© ESO, 2004
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