Mass Formula for a Stationary Axisymmetric Configuration and the Physical Realization of the Kerr Metric

We analyse the expression for the mass of a stationary axisymmetric configuration in general relativity obtained in our previous work [1]. From the generality of our formula and its incompatibility with the corresponding expression in Kerr space-time we argue that a stationary equilibrium distribution of a real matter cannot be a source of the Kerr metric.Comment: RevTex, 5 pages, no figure

Rigidity-dependent cosmic ray energy spectra in the knee region obtained with the GAMMA experiment

On the basis of the extensive air shower (EAS) data obtained by the GAMMA experiment, the energy spectra and elemental composition of the primary cosmic rays are derived in the 1-100 PeV energy range. The reconstruction of the primary energy spectra is carried out using an EAS inverse approach in the framework of the SIBYLL2.1 and QGSJET01 interaction models and the hypothesis of power-law primary energy spectra with rigidity-dependent knees. The energy spectra of primary H, He, O-like and Fe-like nuclei obtained with the SIBYLL interaction model agree with corresponding extrapolations of the balloon and satellite data to ~1 PeV energies. The energy spectra obtained from the QGSJET model show a predominantly proton composition in the knee region. The rigidity-dependent knee feature of the primary energy spectra for each interaction model is displayed at the following rigidities: ~2.5+/-0.2 PV (SIBYLL) and ~3.1-4.2 PV (QGSJET). All the results presented are derived taking into account the detector response, the reconstruction uncertainties of the EAS parameters, and fluctuations in the EAS development.Comment: 28 pages, 18 figures, accepted for publication in Astroparticle Physic