| Abstract
| - Abstract. I use ASCA data to investigate the 2-10 keV X-ray emission of active galactic nuclei (AGN) taken from the ROSAT International X-ray Optical Survey (RIXOS). I find that the integrated spectrum of these faint, soft X-ray-selected AGN in the 2-10 keV band is harder (best-fitting a = 0.8 ± 0.1) than the slope measured with ROSAT between 0.1 and 2 keV, but softer than the 2-10 keV X-ray background, and consistent with the average 2-10 keV spectrum of bright, nearby Seyfert galaxies. With this spectral slope and using measurements of the AGN contribution to the 1-2 keV X-ray background, I estimate that the AGN percentage contribution to the 2-10 keV background is 0.60+0.19+0.14 times the AGN percentage contribution to the 1-2 keV background. Hence AGN produce between 12 and 32 per cent of the 2-10 keV X-ray background. This is only the contribution from the types of AGN which are found in soft X-ray surveys; a population of absorbed AGN could represent an additional component of the 2-10 keV X-ray background.
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