Issue |
A&A
Volume 378, Number 3, November II 2001
|
|
---|---|---|
Page(s) | 735 - 739 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20011271 | |
Published online | 15 November 2001 |
Small-scale fluctuations of the soft X-ray background
1
Nicolaus Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland
2
MPI für extraterrestrische Physik, Giessenbachstr., 85748 Garching, Germany e-mail: mjf@mpe.mpg.de (MJF); jtrumper@mpe.mpg.de (JT)
Corresponding author: A. Soltan, soltan@camk.edu.pl
Received:
1
June
2001
Accepted:
6
September
2001
We report the detection of the X-ray background fluctuations at small angular scales.
ROSAT PSPC archive pointed observations are used to measure the autocorrelation
function (ACF) of the background at scales of -
. The pointings
have been selected from an area apparently free from galactic contamination and
the ACF signal is generated mostly by the extragalactic component of the XRB.
At separations below ~
known X-ray clusters of galaxies become
a substantial source of the background fluctuations. Assuming a power law,
the ACF for all the data has a slope of ~
, but is substantially flatter
(with slope of ~
) when pointings containing bright clusters are removed.
Flattening of the ACF at small separations could indicate existence of
a hot, nonuniformly distributed gas accumulating in wells of gravitational potential.
At separations
-
where the ACF estimates based on the
ROSAT pointings
and All-Sky Survey are available, both data sets give consistent results.
Key words: X-rays: general / diffuse radiation
© ESO, 2001
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