47 research outputs found
Annual modulation of the Galactic binary confusion noise bakground and LISA data analysis
We study the anisotropies of the Galactic confusion noise background and its
effects on LISA data analysis. LISA has two data streams of the gravitational
waves signals relevant for low frequency regime. Due to the anisotropies of the
background, the matrix for their confusion noises has off-diagonal components
and depends strongly on the orientation of the detector plane. We find that the
sky-averaged confusion noise level could change by a factor of 2
in three months, and would be minimum when the orbital position of LISA is
either around the spring or autumn equinox.Comment: 13 pages, 6 figure
Gravitational radiation from a particle in circular orbit around a black hole. V. Black-hole absorption and tail corrections
A particle of mass moves on a circular orbit of a nonrotating black
hole of mass . Under the restrictions and , where
is the orbital velocity, we consider the gravitational waves emitted by such a
binary system. We calculate , the rate at which the gravitational
waves remove energy from the system. The total energy loss is given by , where denotes that part of the
gravitational-wave energy which is carried off to infinity, while
denotes the part which is absorbed by the black hole. We show that the
black-hole absorption is a small effect: . We
also compare the wave generation formalism which derives from perturbation
theory to the post-Newtonian formalism of Blanchet and Damour. Among other
things we consider the corrections to the asymptotic gravitational-wave field
which are due to wave-propagation (tail) effects.Comment: ReVTeX, 17 page
Gravitational waveforms from a point particle orbiting a Schwarzschild black hole
We numerically solve the inhomogeneous Zerilli-Moncrief and Regge-Wheeler
equations in the time domain. We obtain the gravitational waveforms produced by
a point-particle of mass traveling around a Schwarzschild black hole of
mass M on arbitrary bound and unbound orbits. Fluxes of energy and angular
momentum at infinity and the event horizon are also calculated. Results for
circular orbits, selected cases of eccentric orbits, and parabolic orbits are
presented. The numerical results from the time-domain code indicate that, for
all three types of orbital motion, black hole absorption contributes less than
1% of the total flux, so long as the orbital radius r_p(t) satisfies r_p(t)> 5M
at all times.Comment: revtex4, 24 pages, 23 figures, 3 tables, submitted to PR
Graviton Mass from Close White Dwarf Binaries Detectable with LISA
The arrival times of gravitational waves and optical light from orbiting
binaries provide a mechanism to understand the propagation speed of gravity
when compared to that of light or electromagnetic radiation. This is achieved
with a measurement of any offset between optically derived orbital phase
related to that derived from gravitational wave data, at a specified location
of one binary component with respect to the other. Using a sample of close
white dwarf binaries (CWDBs) detectable with the Laser Interferometer Space
Antenna (LISA) and optical light curve data related to binary eclipses from
meter-class telescopes for the same sample, we determine the accuracy to which
orbital phase differences can be extracted. We consider an application of these
measurements involving a variation to the speed of gravity, when compared to
the speed of light, due to a massive graviton. For a subsample of 400
CWDBs with high signal-to-noise gravitational wave and optical data with
magnitudes brighter than 25, the combined upper limit on the graviton mass is
at the level of eV. This limit is two orders of
magnitude better than the present limit derived by Yukawa-correction arguments
related to the Newtonian potential and applied to the Solar-system.Comment: revised version, 8 pages, 5 figures, to appear in PR
Thorough assessment of DNA preservation from fossil bone and sediments excavated from a late Pleistocenee-Holocene cave deposit on Kangaroo Island, South Australia
Fossils and sediments preserved in caves are an excellent source of information for investigating impacts of past environmental changes on biodiversity. Until recently studies have relied on morphology-based palaeontological approaches, but recent advances in molecular analytical methods offer excellent potential for extracting a greater array of biological information from these sites. This study presents a thorough assessment of DNA preservation from late Pleistocene-Holocene vertebrate fossils and sediments from Kelly Hill Cave Kangaroo Island, South Australia. Using a combination of extraction techniques and sequencing technologies, ancient DNA was characterised from over 70 bones and 20 sediment samples from 15 stratigraphic layers ranging in age from >20 ka to ~6.8 ka. A combination of primers targeting marsupial and placental mammals, reptiles and two universal plant primers were used to reveal genetic biodiversity for comparison with the mainland and with the morphological fossil record for Kelly Hill Cave. We demonstrate that Kelly Hill Cave has excellent long-term DNA preservation, back to at least 20 ka. This contrasts with the majority of Australian cave sites thus far explored for ancient DNA preservation, and highlights the great promise Kangaroo Island caves hold for yielding the hitherto-elusive DNA of extinct Australian Pleistocene species
Zoom and whirl: Eccentric equatorial orbits around spinning black holes and their evolution under gravitational radiation reaction
A note on the role of phonological expectations in speech segmentation
Contains fulltext :
5953.pdf (publisher's version ) (Open Access
The nature of arsenic in uranium mill tailings by X-ray absorption spectroscopy
In order to understand the evolving world of environmental issues, the ability to characterize and predict the
stability and bioavailability of heavy métal contaminants in mine waste is becoming increasingly more important. X-ray
Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopies were
used to characterize a series of synthetic and natural samples associated with mine tailings processing. XANES was shown
to be excellent as a tool to rapidly differentiate oxidation states of arsenic within the samples. The EXAFS spectra
provided information on the mineralogy of the precipitated raffinate and tailings and showed that these samples are
composed of a mixture of amorphous ferric arsenates, adsorbed arsenates and a mixture of other poorly ordered arsenates.
Call-Based Dynamic Programming for the Precedence Constrained Line Traveling Salesman
International audienc