13,755 research outputs found
The basics of gravitational wave theory
Einstein's special theory of relativity revolutionized physics by teaching us
that space and time are not separate entities, but join as ``spacetime''. His
general theory of relativity further taught us that spacetime is not just a
stage on which dynamics takes place, but is a participant: The field equation
of general relativity connects matter dynamics to the curvature of spacetime.
Curvature is responsible for gravity, carrying us beyond the Newtonian
conception of gravity that had been in place for the previous two and a half
centuries. Much research in gravitation since then has explored and clarified
the consequences of this revolution; the notion of dynamical spacetime is now
firmly established in the toolkit of modern physics. Indeed, this notion is so
well established that we may now contemplate using spacetime as a tool for
other science. One aspect of dynamical spacetime -- its radiative character,
``gravitational radiation'' -- will inaugurate entirely new techniques for
observing violent astrophysical processes. Over the next one hundred years,
much of this subject's excitement will come from learning how to exploit
spacetime as a tool for astronomy. This article is intended as a tutorial in
the basics of gravitational radiation physics.Comment: 49 pages, 3 figures. For special issue of New Journal of Physics,
"Spacetime 100 Years Later", edited by Richard Price and Jorge Pullin. This
version corrects an important error in Eq. (4.23); an erratum is in pres
Conserved charges of the extended Bondi-Metzner-Sachs algebra
Isolated objects in asymptotically flat spacetimes in general relativity are
characterized by their conserved charges associated with the
Bondi-Metzner-Sachs (BMS) group. These charges include total energy, linear
momentum, intrinsic angular momentum and center-of-mass location, and, in
addition, an infinite number of supermomentum charges associated with
supertranslations. Recently, it has been suggested that the BMS symmetry
algebra should be enlarged to include an infinite number of additional
symmetries known as superrotations. We show that the corresponding charges are
finite and well defined, and can be divided into electric parity "super
center-of-mass" charges and magnetic parity "superspin" charges.
The supermomentum charges are associated with ordinary gravitational-wave
memory, and the super center-of-mass charges are associated with total
(ordinary plus null) gravitational-wave memory, in the terminology of Bieri and
Garfinkle. Superspin charges are associated with the ordinary piece of spin
memory. Some of these charges can give rise to black-hole hair, as described by
Strominger and Zhiboedov. We clarify how this hair evades the no-hair theorems.Comment: 18 pages, 1 table, no figures; some corrections and generalizations
in v2; additional clarifications, corrections, and generalizations in v3; new
table and subsection in v
A power filter for the detection of burst sources of gravitational radiation in interferometric detectors
We present a filter for detecting gravitational wave signals from burst
sources. This filter requires only minimal advance knowledge of the expected
signal: i.e. the signal's frequency band and time duration. It consists of a
threshold on the total power in the data stream in the specified signal band
during the specified time. This filter is optimal (in the Neyman-Pearson sense)
for signal searches where only this minimal information is available.Comment: 3 pages, RevTeX, GWDAW '99 proceedings contribution, submitted to
Int. J. Modern Phys.
Perturbing forces in the lunar gravitational potential, part 3 Final report
Spherical harmonics for evaluating perturbing forces on lunar satellite due to nonsymmetric mass distribution of moo
Data analysis strategies for the detection of gravitational waves in non-Gaussian noise
In order to analyze data produced by the kilometer-scale gravitational wave
detectors that will begin operation early next century, one needs to develop
robust statistical tools capable of extracting weak signals from the detector
noise. This noise will likely have non-stationary and non-Gaussian components.
To facilitate the construction of robust detection techniques, I present a
simple two-component noise model that consists of a background of Gaussian
noise as well as stochastic noise bursts. The optimal detection statistic
obtained for such a noise model incorporates a natural veto which suppresses
spurious events that would be caused by the noise bursts. When two detectors
are present, I show that the optimal statistic for the non-Gaussian noise model
can be approximated by a simple coincidence detection strategy. For simulated
detector noise containing noise bursts, I compare the operating characteristics
of (i) a locally optimal detection statistic (which has nearly-optimal behavior
for small signal amplitudes) for the non-Gaussian noise model, (ii) a standard
coincidence-style detection strategy, and (iii) the optimal statistic for
Gaussian noise.Comment: 5 pages RevTeX, 4 figure
RTCC requirements for mission G - Landing site determination using onboard observations, part 2 Final report
Computer programs for evaluation of telemetered rendezvous radar tracking data of orbiting command module and lunar module landing site determinatio
Deep space network
Background, current status, and sites of Deep Space Network stations are briefly discussed
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