Astrophysics, abstract
astro-ph/0608253

From: Sergei Y. Sazonov [view email]

Date: Fri, 11 Aug 2006 18:32:01 GMT (148kb)

Hard X-ray emission of Earth's atmosphere: Monte Carlo simulations

Authors: S. Sazonov, E. Churazov, R. Sunyaev, M. Revnivtsev

Comments: 11 pages, 15 figures, MNRAS submitted

We perform Monte Carlo simulations of cosmic-ray induced hard X-ray emission in the Earth's atmosphere. We find that the shape of the spectrum emergent from the atmosphere in the energy range ~25-300 keV is determined by Compton scattering and photoabsorption and is virtually independent of the incident cosmic ray spectrum. We provide a fitting formula for the spectral intensity as a function of energy, solar modulation level, geomagnetic cutoff rigidity and zenith angle. A recent measurement of the atmospheric hard X-ray emission together with the cosmic X-ray background by the INTEGRAL observatory agrees with our prediction within 10%. This suggests a possibility of using Earth observations 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 are expected to significantly differ from that emitted by the Earth's atmosphere.

http://arxiv.org/abs/astro-ph/0608253