Issue |
A&A
Volume 410, Number 3, November II 2003
|
|
---|---|---|
Page(s) | 777 - 784 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20031319 | |
Published online | 17 November 2003 |
XMM-Newton discovery of an X-ray filament in Coma
1
Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
2
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, Hawaii 96822, USA
Corresponding author: A. Finoguenov, alexis@xray.mpe.mpg.de
Received:
12
January
2003
Accepted:
12
August
2003
XMM-Newton observations of the outskirts of the Coma cluster
of galaxies confirm the existence of a soft X-ray excess claimed
previously and show it comes from warm thermal emission. Our data
provide a robust estimate of its temperature (~0.2 keV) and
oxygen abundance (~0.1 solar). Using a combination of XMM-Newton
and ROSAT All-Sky Survey data, we rule out a Galactic origin of the
soft X-ray emission. Associating this emission with a 20 Mpc region
in front of Coma, seen in the skewness of its galaxy velocity
distribution, yields an estimate of the density of the warm gas of
∼50 , where fbaryon is the baryon
fraction and
is the critical density
needed to halt the expansion of the universe. Our measurement of the
gas mass associated with the warm emission strongly support its
nonvirialized nature, suggesting that we are observing the warm-hot
intergalactic medium (WHIM). Our measurements provide a direct
estimate of the O, Ne and Fe abundance of the WHIM. Differences with
the reported Ne/O ratio for some OVI absorbers hints at a different
origin of the OVI absorbers and the Coma filament. We argue that the
Coma filament has likely been preheated, but at a substantially lower
level compared to what is seen in the outskirts of groups. The
thermodynamic state of the gas in the Coma filament reduces the
star-formation rate in the embedded spiral galaxies, providing an
explanation for the presence of passive spirals observed in this and
other clusters.
Key words: galaxies: clusters: individual: Coma / cosmology: observations / intergalactic medium / large-scale structure of universe
© ESO, 2003
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