Issue |
A&A
Volume 394, Number 1, October IV 2002
|
|
---|---|---|
Page(s) | 7 - 15 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20021104 | |
Published online | 04 October 2002 |
Warm-hot intergalactic baryons revealed
1
Dipartimento di Astronomia e Scienza dello Spazio, Largo E. Fermi 2, 50125 Firenze, Italy
2
Centro per l'Astronomia Infrarossa e lo studio del mezzo interstellare (CAISMI), CNR, Largo E. Fermi 5, 50125 Firenze, Italy
3
Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
4
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
5
Department of Physical Sciences, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK
Corresponding author: R. Maiolino, maiolino@arcetri.astro.it
Received:
6
June
2002
Accepted:
29
July
2002
Several popular cosmological models predict that most of the baryonic mass
in the local universe is located in filamentary and sheet-like structures
associated with galaxy overdensities.
This gas is expected to be gravitationally heated to ~106 K
and therefore emitting in the soft X-rays.
We have detected diffuse soft X-ray structures in a
high Galactic latitude ROSAT field after point source subtraction and
correction for Galactic absorption.
These diffuse structures have an X-ray
energy distribution that is much softer than expected from clusters, groups or
unresolved emission from AGNs, but are consistent with that
expected from a diffuse warm intergalactic medium.
To discriminate between a Galactic or extragalactic nature of the
diffuse gas we have correlated the soft X–map with multiband optical
images in this field. We have found a significant
overdensity of galaxies in correspondence with the strongest diffuse
X-ray structure. The
photometric redshift distribution of the galaxies over the X-ray peak has
an excess over field galaxies at . This result
strongly suggests that the diffuse X-ray flux is due to extragalactic
emission by
warm gas associated with an overdense galaxy region at
.
Key words: large-scale structure of Universe / X-rays: diffuse background
© ESO, 2002
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