Bruno Deiss - Academia.edu (original) (raw)

Papers by Bruno Deiss

Astronomical observations indicate an accelerated cosmic expansion, the cause of which is explain... more Astronomical observations indicate an accelerated cosmic expansion, the cause of which is explained by the action of `dark energy'. Here we show that in discrete expanding space-time, only a tiny fraction of the vacuum fluctuations can become gravitationally effective and act as a driving `dark' agent. The analytically derived effective vacuum energy density is found to be closely related to the critical cosmic energy density, thus helping to solve the cosmological constant problem as well as the coincidence problem. The proposed model implies that in the present day universe only the vacuum field of the photon and that of the lightest neutrino contribute to the effective vacuum. This allows one to fix the neutrino masses within a narrow range. The model also implies that the (real) universe has to be considered as a thermodynamically open system which exchanges energy and momentum with the virtual reservoir of the vacuum.

Physica Scripta

Some general features of cosmic ray acceleration are summarized along with some inferences that c... more Some general features of cosmic ray acceleration are summarized along with some inferences that can be drawn concerning the origin of the UHE component. The UHE luminosity density is found to be similar to that derived for GeV cosmic rays and its slope suggests a distinct origin. Reports of clustering on small angular scale, if confirmed, would rule out most proposed source models. More generally, it is argued that the highest energy particles can only be accelerated in sites that can induce an EMF E > ∼ 3 × 10 20 V and an associated power L min > ∼ E 2 /Z ∼ 10 39 W, where Z is the characteristic, electrical impedance, typically < ∼ 100Ω. Shock acceleration, unipolar induction and magnetic flares are the three most potent, observed, acceleration mechanisms and radio jet termination shocks, γ-ray blast waves, dormant black holes in galactic nuclei and magnetars are the least implausible, "conventional" manifestations of these mechanisms that have been invoked to explain the UHE cosmic rays. Each of these models presents problems and deciding between these and "exotic" origins for UHE cosmic rays, including those involving new particles or defects will require improved statistical information on the energies, arrival times and directions, as should be provided by the Auger project.

Journal for the History of Astronomy

Astronomy and Astrophysics, Sep 29, 1990

Astronomy and Astrophysics, May 30, 1986

Proceedings of the International Astronomical Union, 1991

... H., Morfill, GE: 1990 ApJ 354400 [4] Lada, CJ, Margukis, M., Dearborn, D.: 1984 ApJ 285141 39... more ... H., Morfill, GE: 1990 ApJ 354400 [4] Lada, CJ, Margukis, M., Dearborn, D.: 1984 ApJ 285141 399 F. Combes and F. Casoli (eds.). ... of transient spiral waves and giant molecular clouds in heating stellar discs by solving the Fokker-Planck equation with a Monte Carlo simulation. ...

Unsolved Problems of the Milky Way, 1996

Astronomy and Astrophysics

The authors derive an equation describing the large-scale motion of the interstellar gas in the p... more The authors derive an equation describing the large-scale motion of the interstellar gas in the presence of small-scale fluctuations, which are considered to be due to the gravitational interaction of the ISM with the system of stars. Of particular interest is a friction term describing the momentum transfer between the interstellar gas and the stellar component due to the small-scale fluctuations.

Astronomy and Astrophysics

Equations for the large-scale energy balance of the gravitationally coupled system of stars and i... more Equations for the large-scale energy balance of the gravitationally coupled system of stars and interstellar gas are derived, including an expression representing the mechanical heating of the ISM by dissipation of turbulent kinetic energy. The mechanical heating rate of the interstellar gas and the dynamical friction between the gas and the stellar system are evaluated. Analytical expressions are derived in a quasi-linear approximation for the mechanical heating rate and the dynamical friction. In dense molecular clouds, with a rich population of young stars or prototstars embedded within the cloud, the resulting mechanical heating rate is of the order of the cosmic ray heating rate. The time scale of dynamical friction is of the order of the free-fall time of the clouds, indicating that the cloud collapse may be considerably delayed.

Astronomy and Astrophysics

The gravitational interaction between stars and interstellar gas is investigated under the influe... more The gravitational interaction between stars and interstellar gas is investigated under the influence of an interstellar magnetic field (IMF). In the present paper the interstellar matter (IM) is considered as a two-component gas consisting of plasma and neutrals. The velocity and density fluctuations of the IM, induced by the system of stars, are modified due to the influence of the IMF. One aspect of the influence of the IMF is, that there are also perturbations perpendicular to the wave propagation, in constrast to the case without the IMF. Because of these perturbations the mean square of the velocity fluctuations is twice what it is in the case without IMF. Equations for the fluctuations of an interacting two-component gas are derived in a framework of a linearized theory.

Proceedings of the International Astronomical Union

Astronomical observations indicate an accelerated cosmic expansion, the cause of which is explain... more Astronomical observations indicate an accelerated cosmic expansion, the cause of which is explained by the action of `dark energy'. Here we show that in discrete expanding space-time, only a tiny fraction of the vacuum fluctuations can become gravitationally effective and act as a driving `dark' agent. The analytically derived effective vacuum energy density is found to be closely related to the critical cosmic energy density, thus helping to solve the cosmological constant problem as well as the coincidence problem. The proposed model implies that in the present day universe only the vacuum field of the photon and that of the lightest neutrino contribute to the effective vacuum. This allows one to fix the neutrino masses within a narrow range. The model also implies that the (real) universe has to be considered as a thermodynamically open system which exchanges energy and momentum with the virtual reservoir of the vacuum.

Physica Scripta

Some general features of cosmic ray acceleration are summarized along with some inferences that c... more Some general features of cosmic ray acceleration are summarized along with some inferences that can be drawn concerning the origin of the UHE component. The UHE luminosity density is found to be similar to that derived for GeV cosmic rays and its slope suggests a distinct origin. Reports of clustering on small angular scale, if confirmed, would rule out most proposed source models. More generally, it is argued that the highest energy particles can only be accelerated in sites that can induce an EMF E > ∼ 3 × 10 20 V and an associated power L min > ∼ E 2 /Z ∼ 10 39 W, where Z is the characteristic, electrical impedance, typically < ∼ 100Ω. Shock acceleration, unipolar induction and magnetic flares are the three most potent, observed, acceleration mechanisms and radio jet termination shocks, γ-ray blast waves, dormant black holes in galactic nuclei and magnetars are the least implausible, "conventional" manifestations of these mechanisms that have been invoked to explain the UHE cosmic rays. Each of these models presents problems and deciding between these and "exotic" origins for UHE cosmic rays, including those involving new particles or defects will require improved statistical information on the energies, arrival times and directions, as should be provided by the Auger project.

Journal for the History of Astronomy

Astronomy and Astrophysics, Sep 29, 1990

Astronomy and Astrophysics, May 30, 1986

Proceedings of the International Astronomical Union, 1991

... H., Morfill, GE: 1990 ApJ 354400 [4] Lada, CJ, Margukis, M., Dearborn, D.: 1984 ApJ 285141 39... more ... H., Morfill, GE: 1990 ApJ 354400 [4] Lada, CJ, Margukis, M., Dearborn, D.: 1984 ApJ 285141 399 F. Combes and F. Casoli (eds.). ... of transient spiral waves and giant molecular clouds in heating stellar discs by solving the Fokker-Planck equation with a Monte Carlo simulation. ...

Unsolved Problems of the Milky Way, 1996

Astronomy and Astrophysics

The authors derive an equation describing the large-scale motion of the interstellar gas in the p... more The authors derive an equation describing the large-scale motion of the interstellar gas in the presence of small-scale fluctuations, which are considered to be due to the gravitational interaction of the ISM with the system of stars. Of particular interest is a friction term describing the momentum transfer between the interstellar gas and the stellar component due to the small-scale fluctuations.

Astronomy and Astrophysics

Equations for the large-scale energy balance of the gravitationally coupled system of stars and i... more Equations for the large-scale energy balance of the gravitationally coupled system of stars and interstellar gas are derived, including an expression representing the mechanical heating of the ISM by dissipation of turbulent kinetic energy. The mechanical heating rate of the interstellar gas and the dynamical friction between the gas and the stellar system are evaluated. Analytical expressions are derived in a quasi-linear approximation for the mechanical heating rate and the dynamical friction. In dense molecular clouds, with a rich population of young stars or prototstars embedded within the cloud, the resulting mechanical heating rate is of the order of the cosmic ray heating rate. The time scale of dynamical friction is of the order of the free-fall time of the clouds, indicating that the cloud collapse may be considerably delayed.

Astronomy and Astrophysics

The gravitational interaction between stars and interstellar gas is investigated under the influe... more The gravitational interaction between stars and interstellar gas is investigated under the influence of an interstellar magnetic field (IMF). In the present paper the interstellar matter (IM) is considered as a two-component gas consisting of plasma and neutrals. The velocity and density fluctuations of the IM, induced by the system of stars, are modified due to the influence of the IMF. One aspect of the influence of the IMF is, that there are also perturbations perpendicular to the wave propagation, in constrast to the case without the IMF. Because of these perturbations the mean square of the velocity fluctuations is twice what it is in the case without IMF. Equations for the fluctuations of an interacting two-component gas are derived in a framework of a linearized theory.

Proceedings of the International Astronomical Union