The BeppoSAX 1-8 keV cosmic background spectrum

Abstract

The spectrum of the 1.0-8.0 keV cosmic X-ray background (CXB) at galactic latitudes > 25 degrees has been measured using the BeppoSAX LECS and MECS instruments. The spectrum is consistent with a power-law of photon index 1.40 +/- 0.04 and normalization 11.7 +/- 0.5 photon cm^{-2} s^{-1} keV^{-1} sr^{-1} at 1 keV. Our results are in good agreement with previous ROSAT PSPC (Georgantopuolos et al. 1996), ASCA GIS (Myaji et al. 1998) and rocket (McCammon & Sanders 1990) measurements. On the contrary, previous measurements with the HEAO1 A2 (Marshall et al. 1980) and the ASCA SIS (Gendreau et al. 1995) instruments, are characterized by normalizations which are respectively 35% and 25% smaller than ours.