Volume 411, Number 3, December I 2003
|Page(s)||329 - 334|
|Section||Cosmology (including clusters of galaxies)|
|Published online||17 November 2003|
The spectrum of the cosmic X-ray background observed by RTXE/PCA
Max-Planck-Institute für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching bei München, Germany
2 Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, 117810 Moscow, Russia
3 Laboratory for High Energy Astrophysics, Code 662, Goddard Space Flight Center, Greenbelt, MD 20771, USA
Corresponding author: M. Revnivtsev, email@example.com
Accepted: 29 August 2003
We have analyzed a large set of RXTE/PCA scanning and slewing observations performed between April 1996 and March 1999. We obtained the 3–20 keV spectrum of the cosmic X-ray background (CXB) by subtracting Earth-occulted observations from observations of the X-ray sky at high galactic latitude and far away from sources. The sky coverage is approximately ~ deg2. The PCA spectrum of CXB in 3–20 keV energy band is adequately approximated by a single power law with photon index and normalization at 1 keV phot/s/cm2/keV/sr. Instrumental background uncertainty precludes accurate RXTE/PCA measurements of the spectrum of cosmic X-ray background at energies above 15 keV and therefore we cannot detect the high energy cutoff observed by the HEAO-1 A2 experiment. Deep observations of the 6 high latitude points used to model the PCA background provide a coarse measure of the spatial variation of the CXB. The CXB variations are consistent with a fixed spectral shape and variable normalization characterized by a fractional rms amplitude of ~7% on angular scales of ~1 square deg.
Key words: cosmology: observations / diffuse radiation / X-rays: general
© ESO, 2003
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