17,527 research outputs found
Bounding the mass of the graviton using binary pulsar observations
The close agreement between the predictions of dynamical general relativity
for the radiated power of a compact binary system and the observed orbital
decay of the binary pulsars PSR B1913+16 and PSR B1534+12 allows us to bound
the graviton mass to be less than 7.6 x 10^{-20} eV with 90% confidence. This
bound is the first to be obtained from dynamic, as opposed to static-field,
relativity. The resulting limit on the graviton mass is within two orders of
magnitude of that from solar system measurements, and can be expected to
improve with further observations.Comment: 16 pages, 1 figure. Added appendix on other choices for mass ter
Regression with strongly correlated data
This paper discusses linear regression of strongly correlated data that
arises, for example, in magnetohydrodynamic equilibrium reconstructions. We
have proved that, generically, the covariance matrix of the estimated
regression parameters for fixed sample size goes to zero as the correlations
become unity. That is, in this limit the estimated parameters are known with
perfect accuracy. Simple examples are shown to illustrate this effect and the
nature of the exceptional cases in which the estimate covariance does not go to
zero
Swift Pointing and Gravitational-Wave Bursts from Gamma-Ray Burst Events
The currently accepted model for gamma-ray burst phenomena involves the
violent formation of a rapidly rotating solar-mass black hole. Gravitational
waves should be associated with the black-hole formation, and their detection
would permit this model to be tested. Even upper limits on the
gravitational-wave strength associated with gamma-ray bursts could constrain
the gamma-ray burst model. This requires joint observations of gamma-ray burst
events with gravitational and gamma-ray detectors. Here we examine how the
quality of an upper limit on the gravitational-wave strength associated with
gamma-ray bursts depends on the relative orientation of the gamma-ray-burst and
gravitational-wave detectors, and apply our results to the particular case of
the Swift Burst-Alert Telescope (BAT) and the LIGO gravitational-wave
detectors. A result of this investigation is a science-based ``figure of
merit'' that can be used, together with other mission constraints, to optimize
the pointing of the Swift telescope for the detection of gravitational waves
associated with gamma-ray bursts.Comment: iop style, 1 figure, 6 pages, presented at GWDAW 200
Addressing LISA Science Analysis Challenges
The principal goal of the \emph{LISA Science Analysis Workshop} is to
encourage the development and maturation of science analysis technology in
preparation for LISA science operations. Exactly because LISA is a pathfinder
for a new scientific discipline -- gravitational wave astronomy -- LISA data
processing and science analysis methodologies are in their infancy and require
considerable maturation if they are to be ready to take advantage of LISA data.
Here we offer some thoughts, in anticipation of the LISA Science Analysis
Workshop, on analysis research problems that demonstrate the capabilities of
different proposed analysis methodologies and, simultaneously, help to push
those techniques toward greater maturity. Particular emphasis is placed on
formulating questions that can be turned into well-posed problems involving
tests run on specific data sets, which can be shared among different groups to
enable the comparison of techniques on a well-defined platform.Comment: 7 page
Recommended from our members
Addressing School Dropout in Texas: A Summary for Administrators and Policymakers of "Dropout Prevention: A Practice Guide"
This booklet summarizes the information from: Dropout Prevention: A Practice Guide, available on the Institute of Education Sciences web site at http://ies.ed.gov/ncee/wwc.Educatio
The Testbed for LISA Analysis Project
The Testbed for LISA Analysis (TLA) Project aims to facilitate the
development, validation and comparison of different methods for LISA science
data analysis, by the broad LISA Science Community, to meet the special
challenges that LISA poses. It includes a well-defined Simulated LISA Data
Product (SLDP), which provides a clean interface between the communities that
have developed to model and to analyze the LISA science data stream; a
web-based clearinghouse (at ) providing SLDP
software libraries, relevant software, papers and other documentation, and a
repository for SLDP data sets; a set of mailing lists for communication between
and among LISA simulators and LISA science analysts; a problem tracking system
for SLDP support; and a program of workshops to allow the burgeoning LISA
science community to further refine the SLDP definition, define specific LISA
science analysis challenges, and report their results. This note describes the
TLA Project, the resources it provides immediately, its future plans, and
invites the participation of the broader community in the furtherance of its
goals.Comment: 5 pages, no figure
- âŠ