62,385 research outputs found
Independent analysis of the orbits of Pioneer 10 and 11
Independently developed orbit determination software is used to analyze the
orbits of Pioneer 10 and 11 using Doppler data. The analysis takes into account
the gravitational fields of the Sun and planets using the latest JPL
ephemerides, accurate station locations, signal propagation delays (e.g., the
Shapiro delay, atmospheric effects), the spacecrafts' spin, and maneuvers. New
to this analysis is the ability to utilize telemetry data for spin, maneuvers,
and other on-board systematic effects. Using data that was analyzed in prior
JPL studies, the anomalous acceleration of the two spacecraft is confirmed. We
are also able to put limits on any secondary acceleration (i.e., jerk) terms.
The tools that were developed will be used in the upcoming analysis of recently
recovered Pioneer 10 and 11 Doppler data files.Comment: 22 pages, 5 figures; accepted for publication in IJMP
Feasibility of UV lasing without inversion in mercury vapor
We investigate the feasibility of UV lasing without inversion at a wavelength
of nm utilizing interacting dark resonances in mercury vapor. Our
theoretical analysis starts with radiation damped optical Bloch equations for
all relevant 13 atomic levels. These master equations are generalized by
considering technical phase noise of the driving lasers. From the Doppler
broadened complex susceptibility we obtain the stationary output power from
semiclassical laser theory. The finite overlap of the driving Gaussian laser
beams defines an ellipsoidal inhomogeneous gain distribution. Therefore, we
evaluate the intra-cavity field inside a ring laser self-consistently with
Fourier optics. This analysis confirms the feasibility of UV lasing and reveals
its dependence on experimental parameters.Comment: changes were made according to reviewer comments (accepted for
publication in JOSA B
Post-Newtonian Theory for Precision Doppler Measurements of Binary Star Orbits
The determination of velocities of stars from precise Doppler measurements is
described here using relativistic theory of astronomical reference frames so as
to determine the Keplerian and post-Keplerian parameters of binary systems. We
apply successive Lorentz transformations and the relativistic equation of light
propagation to establish the exact treatment of Doppler effect in binary
systems both in special and general relativity theories. As a result, the
Doppler shift is a sum of (1) linear in terms, which include the
ordinary Doppler effect and its variation due to the secular radial
acceleration of the binary with respect to observer; (2) terms proportional to
, which include the contributions from the quadratic Doppler effect
caused by the relative motion of binary star with respect to the Solar system,
motion of the particle emitting light and diurnal rotational motion of
observer, orbital motion of the star around the binary's barycenter, and
orbital motion of the Earth; and (3) terms proportional to , which
include the contributions from redshifts due to gravitational fields of the
star, star's companion, Galaxy, Solar system, and the Earth. After
parameterization of the binary's orbit we find that the presence of
periodically changing terms in the Doppler schift enables us disentangling
different terms and measuring, along with the well known Keplerian parameters
of the binary, four additional post-Keplerian parameters, including the
inclination angle of the binary's orbit, . We briefly discuss feasibility of
practical implementation of these theoretical results, which crucially depends
on further progress in the technique of precision Doppler measurements.Comment: Minor changes, 1 Figure included, submitted to Astrophys.
Lorentz Covariant Theory of Light Propagation in Gravitational Fields of Arbitrary-Moving Bodies
The Lorentz covariant theory of propagation of light in the (weak)
gravitational fields of N-body systems consisting of arbitrarily moving
point-like bodies with constant masses is constructed. The theory is based on
the Lienard-Wiechert presentation of the metric tensor. A new approach for
integrating the equations of motion of light particles depending on the
retarded time argument is applied. In an approximation which is linear with
respect to the universal gravitational constant, G, the equations of light
propagation are integrated by quadratures and, moreover, an expression for the
tangent vector to the perturbed trajectory of light ray is found in terms of
instanteneous functions of the retarded time. General expressions for the
relativistic time delay, the angle of light deflection, and gravitational red
shift are derived. They generalize previously known results for the case of
static or uniformly moving bodies. The most important applications of the
theory are given. They include a discussion of the velocity dependent terms in
the gravitational lens equation, the Shapiro time delay in binary pulsars, and
a precise theoretical formulation of the general relativistic algorithm of data
processing of radio and optical astrometric measurements in the non-stationary
gravitational field of the solar system. Finally, proposals for future
theoretical work being important for astrophysical applications are formulated.Comment: 77 pages, 7 figures, list of references is updated, to be published
in Phys. Rev. D6
Interference at quantum transitions: lasing without inversion and resonant four-wave mixing in strong fields at Doppler-broadened transitions
An influence of nonlinear interference processes at quantum transitions under
strong resonance electromagnetic fields on absorption, amplification and
refractive indices as well as on four-wave mixing processes is investigated.
Doppler broadening of the coupled transitions, incoherent excitation,
relaxation processes, as well as power saturation processes associated with the
coupled levels are taken into account. Both closed (ground state is involved)
and open (only excited states are involved) energy level configurations are
considered. Common expressions are obtained which allow one to analyze the
optical characteristics (including gain without inversion and enhanced
refractive index at vanishing absorption) for various V, Lambda and H
configurations of interfering transitions by a simple substitution of
parameters. Similar expressions for resonant four-wave mixing in Raman
configurations are derived too. Crucial role of Doppler broadening is shown.
The theory is applied to numerical analysis of some recent and potential
experiments.Comment: 12 pages, 9 eps figures, invited paper, Proceedings of the 11th
International Vavilov Conference on Nonlinear Optic
Interstellar travels aboard radiation-powered rockets
We model accelerated trips at high-velocity aboard light sails (beam-powered
propulsion in general) and radiation rockets (thrust by anisotropic emission of
radiation) in terms of Kinnersley's solution of general relativity and its
associated geodesics. The analysis of radiation rockets relativistic kinematics
shows that the true problem of interstellar travel is not really the amount of
propellant, nor the duration of the trip but rather its tremendous energy cost.
Indeed, a flyby of Proxima Centauri with an ultralight gram-scale laser sail
would require the energy produced by a 1 GW power plant during about one day,
while more than 15 times the current world energy production would be required
for sending a 100 tons radiation rocket to the nearest star system. The
deformation of the local celestial sphere aboard radiation rockets is obtained
through the null geodesics of Kinnersley's spacetime in the Hamiltonian
formulation. It is shown how relativistic aberration and Doppler effect for the
accelerated traveller differ from their description in special relativity for
motion at constant velocity. We also show how our results could interestingly
be extended to extremely luminous events like the large amount of gravitational
waves emitted by binary black hole mergers.Comment: 18 pages, 11 figures ; Open Acces
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