2006/08/31 by S. Sazonov, E. Churazov, R. Sunyaev +1 · 2 citations
Medicine · Physics and Astronomy · #Nuclear Physics and Applications #Radiation Detection and Scintillator Technologies #Radiation Therapy and Dosimetry #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2007.11746.x
published as Mon.Not.Roy.Astron.Soc.377:1726-1736,2007 · 12 pages, 16 figures, MNRAS accepted
arxiv created 2007/03/20 · openalex publication_date 2007/05/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We perform Monte Carlo simulations of cosmic ray-induced hard X-ray radiation from the Earth's atmosphere. We find that the shape of the spectrum emergent from the atmosphere in the energy range 25–300 keV is mainly determined by Compton scatterings and photoabsorption, and is almost insensitive to the incident cosmic ray spectrum. We provide a fitting formula for the hard X-ray surface brightness of the atmosphere as would be measured by a satellite-borne instrument, as a function of energy, solar modulation level, geomagnetic cut-off rigidity and zenith angle. A recent measurement by the INTEGRAL observatory of the atmospheric hard X-ray flux during the occultation of the cosmic X-ray background by the Earth agrees with our prediction within 10 per cent. This suggests that Earth observations could be used for in-orbit calibration of future hard X-ray telescopes. We also demonstrate that the hard X-ray spectra generated by cosmic rays in the crusts of the Moon, Mars and Mercury should be significantly different from that emitted by the Earth's atmosphere.