EDP Sciences
Free Access
Volume 421, Number 3, July III 2004
Page(s) 1021 - 1030
Section Interstellar and circumstellar matter
DOI https://doi.org/10.1051/0004-6361:20034554

A&A 421, 1021-1030 (2004)
DOI: 10.1051/0004-6361:20034554

Non-thermal X-ray emission from young supernova remnants

E. van der Swaluw1, 2 and A. Achterberg1

1  Astronomical Institute, Utrecht University, PO Box 80000, 3508 TA Utrecht, The Netherlands
2  FOM-Institute for Plasma Physics Rijnhuizen, PO Box 1207, 3430 BE Nieuwegein, The Netherlands

(Received 21 October 2003 / Accepted 8 March 2004)

The Galactic (nucleonic) cosmic-ray spectrum up to the knee ( $E\sim 10^{15}$ eV) is attributed to acceleration processes that take place near the external shocks around supernova remnants (SNRs). Theoretical predictions based on the theory of diffusive shock acceleration give a similar estimate for the maximum particle energy that can be reached at these shocks: $E \sim 10^{14}{-}10^{15}$ eV. Electrons with energies $E \sim 10^{14}$ eV radiate X-ray photons in the ~ $10{-}100 \; \mu$G magnetic fields present in many young SNRs. These electrons near the knee give rise to a non-thermal X-ray component in the spectrum of young supernova remnants. Recent observations of SN1006 and G347.3-0.5 confirm this prediction.

We have combined hydrodynamical calculations of the evolution of a young remnant with an algorithm that simultaneously calculates the acceleration of electrons, their radiation losses and the synchrotron spectrum of a young supernova remnant. The electrons are treated using a test-particle approximation.

We give a semi-analytical estimate of the maximum electron energy and typical synchrotron frequencies for young remnants at the end of the free-expansion stage of their evolution. We present spectra of the energy distribution of the electrons in a young supernova remnant, and construct a synchrotron map in the X-ray domain, assuming Bohm diffusion within the remnant and a shock-compressed magnetic field.

Key words: ISM: cosmic rays -- ISM: supernova remnants -- shock waves -- acceleration of particles

Offprint request: E. van der Swaluw, swaluw@rijnh.nl

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