Gravitational-wave bursts from the nuclei of distant galaxies and quasars: Proposal for detection using Doppler tracking of interplanetary spacecraft

Supermassive black holes which exist in the nuclei of many quasars and galaxies are examined along with the collapse which forms these holes and subsequent collisions between them which produce strong, broad-band bursts of gravitational waves. Such bursts might arrive at earth as often as 50 times per year--or as rarely as once each 300 years. The detection of such bursts with dual-frequency Doppler tracking of interplanetary spacecraft is considered

Magnetospheric electrons

Coupling of source, transport, and sink processes produces a fairly accurate model for the macroscopic structure and dynamics of magnetospheric electrons. Auroral electrons are controlled by convective transport from a plasma sheet source coupled with a precipitation loss due to whistler and electrostatic plasma turbulence. Outer and inner zone electrons are governed by radial diffusion transport from convection and acceleration sources external to the plasmapause and by parasitic precipitation losses arising from cyclotron and Landau interactions with whistler and ion cyclotron turbulence

On the structure of line-driven winds near black holes

A general physical mechanism of the formation of line-driven winds at the vicinity of strong gravitational field sources is investigated in the frame of General Relativity. We argue that gravitational redshifting should be taken into account to model such outflows. The generalization of the Sobolev approximation in the frame of General Relativity is presented. We consider all processes in the metric of a nonrotating (Schwarzschild) black hole. The radiation force that is due to absorbtion of the radiation flux in lines is derived. It is demonstrated that if gravitational redshifting is taken into account, the radiation force becomes a function of the local velocity gradient (as in the standard line-driven wind theory) and the gradient of $g_{00}$. We derive a general relativistic equation of motion describing such flow. A solution of the equation of motion is obtained and confronted with that obtained from the Castor, Abbott & Klein (CAK) theory. It is shown that the proposed mechanism could have an important contribution to the formation of line-driven outflows from compact objects.Comment: 20 pages, submitted to Ap

The geometry of a naked singularity created by standing waves near a Schwarzschild horizon, and its application to the binary black hole problem

The most promising way to compute the gravitational waves emitted by binary black holes (BBHs) in their last dozen orbits, where post-Newtonian techniques fail, is a quasistationary approximation introduced by Detweiler and being pursued by Price and others. In this approximation the outgoing gravitational waves at infinity and downgoing gravitational waves at the holes' horizons are replaced by standing waves so as to guarantee that the spacetime has a helical Killing vector field. Because the horizon generators will not, in general, be tidally locked to the holes' orbital motion, the standing waves will destroy the horizons, converting the black holes into naked singularities that resemble black holes down to near the horizon radius. This paper uses a spherically symmetric, scalar-field model problem to explore in detail the following BBH issues: (i) The destruction of a horizon by the standing waves. (ii) The accuracy with which the resulting naked singularity resembles a black hole. (iii) The conversion of the standing-wave spacetime (with a destroyed horizon) into a spacetime with downgoing waves by the addition of a ``radiation-reaction field''. (iv) The accuracy with which the resulting downgoing waves agree with the downgoing waves of a true black-hole spacetime (with horizon). The model problem used to study these issues consists of a Schwarzschild black hole endowed with spherical standing waves of a scalar field. It is found that the spacetime metric of the singular, standing-wave spacetime, and its radiation-reaction-field-constructed downgoing waves are quite close to those for a Schwarzschild black hole with downgoing waves -- sufficiently close to make the BBH quasistationary approximation look promising for non-tidally-locked black holes.Comment: 12 pages, 6 figure

Schwarzschild black holes as unipolar inductors: expected electromagnetic power of a merger

(Abridged) The motion of a Schwarzschild black hole with velocity $v_0 = \beta_0 c$ through a constant magnetic field $B_0$ in vacuum induces a component of the electric field along the magnetic field, generating a non-zero second Poincare electromagnetic invariant $^* F \cdot F \neq 0$. This will produce (e.g., via radiative effects and vacuum breakdown) an electric charge density of the order of $\rho_{\rm ind}= B_0 \beta_0 /(2 \pi e R_G)$, where $R_G = 2 G M/c^2$ is the Schwarzschild radius and $M$ is the mass of the black hole; the charge density $\rho_{\rm ind}$ is similar to the Goldreich-Julian density. The magnetospheres of moving black holes resemble in many respects the magnetospheres of rotationally-powered pulsars, with pair formation fronts and outer gaps, where the sign of the induced charge changes. As a result, the black hole will generate bipolar electromagnetic jets each consisting of two counter-aligned current flows (four current flows total), each carrying an electric current of the order $I \approx e B_0 R_G \beta_0$. The electromagnetic power of the jets is $L \approx (G M)^2 B_0^2 \beta_0^2/c^3$; for a particular case of merging black holes the resulting Poynting power is $L \approx {(G M)^3 B_0^2 /(c^5 R)}$, where $R$ is the radius of the orbit. In addition, in limited regions near the horizon the first electromagnetic invariant changes sign, so that the induced electric field becomes larger than the magnetic field, $E>B$. The total energy loss from a system of merging BHs is a sum of two components with similar powers, one due to the rotation of space-time within the orbit, driven by the non-zero angular momentum in the system, and the other due to the linear motion of the BHs through the magnetic field.Comment: Phys. Rev. D accepte

A unified theory of stable auroral red arc formation at the plasmapause

A theory is proposed that SAR-arcs are generated at the plasmapause as a consequence of the turbulent dissipation of ring current energy. During the recovery phase of a geomagnetic storm, the plasmapause expands outward into the symmetric ring current. When the cold plasma densities reach about 100/cu cm, ring current protons become unstable and generate intense ion cyclotron wave turbulence in a narrow region 1/2 earth radius wide (just inside the plasmapause). Approximately one-half of the ring current energy is dissipated into wave turbulence which in turn is absorbed through a Landau resonant interaction with plasma spheric electrons. The combined thermal heat flux to the ionosphere due to Landau absorption of the wave energy and proton-electron Coulomb dissipation is sufficient to drive SAR-arcs at the observed intensities. It is predicted that the arcs should be localized to a narrow latitudinal range just within the stormtime plasmapause. They should occur at all local times and persist for the 10 to 20 hour duration of the plasma-pause expansion

Domain Wall Depinning in Random Media by AC Fields

The viscous motion of an interface driven by an ac external field of frequency omega_0 in a random medium is considered here for the first time. The velocity exhibits a smeared depinning transition showing a double hysteresis which is absent in the adiabatic case omega_0 --> 0. Using scaling arguments and an approximate renormalization group calculation we explain the main characteristics of the hysteresis loop. In the low frequency limit these can be expressed in terms of the depinning threshold and the critical exponents of the adiabatic case.Comment: 4 pages, 3 figure