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Aims. The properties of the Galactic supernova remnant (SNR) SN 1006 are theoretically reanalysed.

Aims. The consequences of a newly suggested value for the SN explosion energy Esn= 1.2 $\times$1051erg are explored for the case of Tycho's supernova remnant (SNR).

Aims.Nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to investigate the properties of Kepler's SNR and, in particular, to predict the γ-ray spectrum expected from this SNR.

We use nonlinear kinetic theory to study the remnant dynamics and the particle acceleration as well as the properties of the nonthermal emission from the supernova remnant SN 1006. The known range of astronomical parameters is examined to determine whether it encompasses the existing synchrotron emission data. Given the present-day spatial extent and expansion rate of the object, it is shown that the hadronic gamma-ray flux is very sensitive to the ambient gas density $N_{\mathrm H}$and that the existing HESS upper limit requires $N_{\mathrm H} < 0.1$cm-3. The strength of the amplified magnetic field downstream of the shock is about 150 μG.

It is shown that amplification of the magnetic field in supernova remnants (SNRs) occurs in all six objects where morphological measurements are presently available in the hard X-ray continuum at several keV. For the three archetypical objects (SN 1006, Cas Aand Tycho's SNR) to which nonlinear time-dependent acceleration theory has been successfully applied up to now, the global theoretical and the local observational field strengths agree very well, suggesting in addition that all young SNRs exhibit the amplification effect as a result of very efficient acceleration of nuclear cosmic rays (CRs) at the outer shock. Since this appears to be empirically the case, we may reverse the argument and consider field amplification as a measure of nuclear CR acceleration and it has indeed been argued that acceleration in the amplified fields allows the CR spectrum from SNRs to reach the knee in the spectrum or, in special objects, even beyond. The above results are furthermore used to investigate the time evolution of field amplification in young SNRs. Although the uncertainties in the data do not allow precise conclusions regarding this point, they rather clearly show that the ratio of the magnetic field energy density and the kinetic energy density of gas flow into the shock is of the order of a few percent if the shock speed is high enough $V_{\rm s}>10^3$km s-1, and this ratio remains nearly constant during the SNR evolution. The escape of the highest energy nuclear particles from their sources becomes progressively important with age, reducing also the cutoff in the $\pi^0$-decay gamma-ray emission spectrum with time after the end of the sweep-up phase. Simultaneously the leptonic gamma-ray channels will gain in relative importance with increasing age of the sources.

It is shown that the nonlinear kinetic model of cosmic ray (CR) acceleration in supernova remnants (SNRs) fits the shell-type nonthermal X-ray morphology, obtained in Chandra observations, in a satisfactory way. The set of empirical parameters is the same which reproduces the dynamical properties of the SNR and the spectral characteristics of the emission produced by CRs. The extremely small spatial scales of the observed X-ray distribution are due to the large effective magnetic field $B_{\rm d}\sim 100$µG in the interior, which is also required to give a good fit for the spatially integrated radio and X-ray synchrotron spectra. The only reasonably thinkable condition for the production of such a large effective field strength is an efficiently accelerated nuclear CR component. Therefore the Chandra data confirm the inference that SN 1006 indeed accelerates nuclear CRs with the high efficiency required for SNRs to be considered as the main Galactic CR sources.

We study the production of cosmic rays (CRs) in supernova remnants (SNRs), including the reacceleration of background galactic cosmic rays (GCRs) – thus refining the early considerations by Blandford & Ostriker (1980) and Wandel et al. (1987) – and the effects of the nuclear spallation inside the sources (the SNRs). This combines for the first time nuclear spallation inside CR sources and in the diffuse interstellar medium, as well as reacceleration, with the injection and subsequent acceleration of suprathermal particles from the postshock thermal pool. Selfconsistent CR spectra are calculated on the basis of the nonlinear kinetic model. It is shown that GCR reacceleration and CR spallation produce a measurable effect at high energies, especially in the secondary to primary (s/p) ratio, making its energy-dependence substantially flatter than predicted by the standard model. Quantitatively, the effect depends strongly upon the density of the surrounding circumstellar matter. GCR reacceleration dominates secondary CR production for a low circumstellar density. It increases the expected s/p ratio substantially and flattens its spectrum to an almost energy-independent form for energies larger than 100 GeV/n if the supernovae explode on average into a hot dilute medium with hydrogen number density $N_{\rm H}=0.003$cm-3. The contribution of CR spallation inside SNRs to the s/p ratio increases with increasing circumstellar density and becomes dominant for $N_{\rm H}\ga 1$cm-3, leading at high energies to a flat s/p ratio which is only by a factor of three lower than in the case of the hot medium. Measurements of the boron to carbon ratio at energies above 100 GeV/n could be used in comparison with the values predicted here as a consistency test for the supernova origin of the GCRs.

The injection rate of suprathermal protons into the diffusive shock acceleration process should vary strongly over the surface of supernova remnant shocks. These variations and the absolute value of the injection rate are investigated. In the simplest case, like for SN 1006, the shock can be approximated as spherical in a uniform large-scale magnetic field. The injection rate depends strongly on the shock obliquity and diminishes as the angle between the ambient field and the shock normal increases. Therefore efficient particle injection, which leads to conversion of a significant fraction of the kinetic energy at a shock surface element, arises only in relatively small regions near the “poles”, reducing the overall CR production. The sizes of these regions depend strongly on the random background field and the Alfvén wave turbulence generated due to the CR streaming instability. For the cases of SN 1006 and Tycho's SNR they correspond to about 20, and for Cas A to between 10 and 20 percent of the entire shock surface. In a first approximation, the CR production rate, calculated under the assumption of spherical symmetry, has therefore to be renormalized by this factor, while the shock as such remains roughly spherical.

A nonlinear kinetic model of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to describe the properties of Tycho's SNR. Observations of the expansion characteristics and of the nonthermal radio and X-ray emission spectra, assumed to be of synchrotron origin, are used to constrain the overall dynamical evolution and the particle acceleration parameters of the system, in addition to what is known from independent estimates of the distance and thermal X-ray observations. It is shown that a very efficient production of nuclear cosmic rays, leading to strong shock modification, and a large downstream magnetic field strength $B_\mathrm{d}\approx240$μG are required to reproduce the observed synchrotron emission from radio to X-ray frequencies. This field strength is still well within the upper bound for the effective magnetic field, consistent with the acceleration process. The $\pi^0$-decay γ-ray flux turns out to be somewhat greater than the inverse Compton (IC) flux off the Cosmic Microwave Background at energies below 1 TeV, dominating it strongly at 10 TeV. The predicted TeV γ-ray flux is consistent with but close to the very low upper limit recently obtained by HEGRA. A future detection at $\epsilon_{\gamma} \sim 10$TeV would clearly indicate hadronic emission.

The nonlinear kinetic model of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to describe the properties of the remnant of SN 1006. It is shown, that the theory fits the existing data in a satisfactory way within a set of parameters which is consistent with the idea that SN 1006 is a typical source of Galactic CR nucleons, although not necessarily of CR electrons. The adjusted parameters are those that are not very well determined by present theory or not directly amenable to astronomical observations. The calculated expansion law and the radio-, X-ray and γ-ray emissions produced by the accelerated CRs in SN 1006 agree quite well with the observations. A rather large interior magnetic field $B_\mathrm{d}\approx 100$μG is required to give a good fit for the radio and X-ray synchrotron emission. In the predicted TeV γ-ray flux from SN 1006, the $\pi^0$-decay γ-rays, generated by the nuclear CR component, dominate over the inverse Compton (IC) γ-rays, generated by the CR electrons in the cosmic microwave background. The predicted source morphology in high energy γ-rays roughly corresponds to that of the synchrotron emission. The predicted integral γ-ray flux $F_{\gamma}\propto \epsilon_{\gamma}^{-1}$extends up to energies ~100 TeV if CR diffusion is as strong as the Bohm limit. Only if the interior magnetic field is much lower in the SNR, $B_\mathrm{d}\approx 10$μG, then the observed γ-ray emission can be due to the accelerated electron component alone. In this case, not plausible physically in our view, the lowest permissible value of the electron to proton ratio is rather high, and the maximum individual energy and total energy content of accelerated nucleons so small, that SN 1006 can not be considered as a typical source of the nuclear Galactic CRs.