Cosmological γ-ray bursts from a neutron star collapse induced by a primordial black hole

A detailed analysis is presented for a novel scenario in which gamma-ray bursts are of intergalactic origin and arise from the induced collapse of an isolated neutron star triggered by a primordial black hole. The energy released from the phase transition of accreted nucleon matter into a quark-gluon plasma is transferred by degenerate neutrinos to the star’s surface, where neutrinos annihilate into an electron-positron plasma and produce an inverted temperature layer that preserves a fire-ball from undue baryonic pollution. Possible observational tests include the absence of apparent cosmological time dilation, the location of γ-ray bursts primarily outside of galaxies, a specific shape of the log N-log S curve, with a large peak near red shift z∼10, the emission of ∼10⁻³ of the total energy in the form of 100-GeV photons, a bimodal distribution of durations, a very weak accompanying pulse of gravitational radiation, etc. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 10, 642–647 (25 November 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Parametric effect in a superradiant laser with self-mode-locking

Theoretical and Mathematical Physics - Based on numerical simulation of the nonstationary working of a CW superradiant laser with a low-Q combined Fabry-Perot cavity with distributed feedback of...     

Polariton-mode lasing and Bose condensate of dipolar excitons in heterostructures

The analysis of the polariton modes in 2D traps based on heterostructures with quantum wells for Bose-Einstein condensation of dipolar excitons is presented. The characteristic equation of such modes is derived with allowance for the polarization relaxation of excitons and radiative losses from the trap. The spectrum and structure of high-quality modes are analytically and numerically studied. It is demonstrated that several modes become unstable at a high enough density of excitons and a long relaxation time of the exciton polarization. In accordance with the estimations, such an instability can be reached in the experiments on the Bose-Einstein condensation of dipolar excitons and can be used to interpret the corresponding coherent emission.     

Mode interaction and dynamics features of class d lasers

We study a simple model of the class D laser with allowance for the spectral and spatial inhomogeneity of an active medium, whose polarization relaxation rate is much smaller than the field relaxation rate in a resonator. We consider the cases of one-, two-, and four-mode lasing for which the stationary, pulsed, self-modulation, and quasi-chaotic of laser dynamics are numerically studied. The laser parameters are chosen to correspond to the experiments on the Bose–Einstein condensation of dipolar excitons in semiconductor traps with quantum wells, which open up a possibility for creating class D lasers for the first time.     

Meissner effect in supercoducting cores of neutron stars

Evolution of the magnetic field of a neutron star (pulsar) under the influence of the superconductivity of a proton plasma in the stellar core is considered. The magnetic field expulsion from the core due to the Meissner effect for the second-type npe-superconductor is shown to be inefficient for the magnetic fields B ₀<10¹⁴ G. Therefore, neglecting other expulsion mechanisms (e.g., related to the buoyancy of the Abrikosov vortices or their pinning to the Onsager-Feynman vortices in the superfluid interior of the rotating star), such magnetic fields should be frozen into the core for>10¹⁰ years, i.e., during the entire lifetime of the star.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 1, pp. 26–33, January, 1996.In conclusion, authors wish to thank V. V. Kurin, Yu. V. Petukhov, D. A. Ryndyk, and V. Yu. Trakhtengerts for discussion of the problems of vortex dynamics and magnetic field evolution on neutron stars.     

Gamma-ray spectral features of neutron stars originating from photon splitting in a strong magnetic field

The spectral evolution of the soft (≲1 MeV) gamma-ray radiation of neutron stars in a strong magnetic field (B ≳ 6·10¹² G) is analyzed. It is shown that the radiation transfer equation for the photon splitting cascade has a one-parameter set of self-similar solutions whose integral expansion is an efficient method for study of the general solution. An arbitrary initial spectrum converges quickly to a self-similar solution provided that most of the radiation energy is concentrated in the hard spectral range. We consider the possible observational consequences of the photon splitting, including the polarization and softening of the output spectrum as well as the occurrence of a spectral break and condensation of all hard-energy radiation near that break. Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, radiofizika, Vol. 40, Nos. 1–2, pp. 146–160, January–February, 1997.     

Experimental study of nonlinear mode mixing in dual-wavelength semiconductor lasers

New schemes for the generation of the sum, difference, and double frequencies in dual-wavelength injection lasers, based on an intracavity nonlinear mode mixing owing to a bulk nonlinearity, are experimentally investigated. Namely, the operation of the dual-wavelength laser diodes at the TE₀ and TE₁ modes, butt-joint laser diodes, and interband cascade lasers with tunnel junction are described.     

Features of the generation of a collisionless electrostatic shock wave in a laser-ablation plasma

The appearance of a density bump is experimentally revealed in an electrostatic shock wave during the ablation of an aluminum foil by a femtosecond laser pulse. The numerical simulation shows that this phenomenon can be explained by the generation of a packet of ion acoustic waves under the action of high-energy electron flows in a collisionless plasma. It is found that, for the formation and maintenance of the dense plasma layer in the shock wave, the contributions of accelerated ions overtaking it and wave-captured ions of the background plasma formed by a nanosecond laser prepulse in the process of ablation are significant.     

Coherent radiation from neutral molecules moving above a grating

We predict and study the effect of parametric self-induced excitation of a molecule moving above the dielectric or conducting medium with periodic grating. In this case the radiation reaction force modulates the molecular transition frequency which results in a parametric instability of dipole oscillations even from the level of quantum or thermal fluctuations. The present mechanism of instability of electrically neutral molecules is different from that of the well-known Smith-Purcell and transition radiation in which a moving charge and its oscillating image create an oscillating dipole. We show that parametrically excited molecular bunches can produce an easily detectable coherent radiation flux of up to a microwatt.