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Articles 1 - 14 of 14
Full-Text Articles in Physical Sciences and Mathematics
Upper Bounds On The Low-Frequency Stochastic Gravitational Wave Background From Pulsar Timing Observations: Current Limits And Future Prospects, F. A. Jenet, G. B. Hobbs, W. Van Straten, R. N. Manchester, M. Bailes, J. P.W. Verbiest, R. T. Edwards, A. W. Hotan, J. M. Sarkissian, S. M. Ord
Upper Bounds On The Low-Frequency Stochastic Gravitational Wave Background From Pulsar Timing Observations: Current Limits And Future Prospects, F. A. Jenet, G. B. Hobbs, W. Van Straten, R. N. Manchester, M. Bailes, J. P.W. Verbiest, R. T. Edwards, A. W. Hotan, J. M. Sarkissian, S. M. Ord
Physics and Astronomy Faculty Publications and Presentations
Using a statistically rigorous analysis method, we place limits on the existence of an isotropic stochastic gravitational wave background using pulsar timing observations. We consider backgrounds whose characteristic strain spectra may be described as a power-law dependence with frequency. Such backgrounds include an astrophysical background produced by coalescing supermassive black-hole binary systems and cosmological backgrounds due to relic gravitational waves and cosmic strings. Using the best available data, we obtain an upper limit on the energy density per unit logarithmic frequency interval of ΩgSMBH[1/(8 yr)}h2 ≤ 1.9 × 10-8 for an astrophysical background that is 5 times more stringent than …
The P14 Fusion-Associated Small Transmembrane (Fast) Protein Effects Membrane Fusion From A Subset Of Membrane Microdomains, Jennifer A. Corcoran, Jayme Salsman, Roberto De Antueno, Ahmed Touhami, Manfred H. Jericho, Eileen K. Clancy, Roy Duncan
The P14 Fusion-Associated Small Transmembrane (Fast) Protein Effects Membrane Fusion From A Subset Of Membrane Microdomains, Jennifer A. Corcoran, Jayme Salsman, Roberto De Antueno, Ahmed Touhami, Manfred H. Jericho, Eileen K. Clancy, Roy Duncan
Physics and Astronomy Faculty Publications and Presentations
The reovirus fusion-associated small transmembrane (FAST) proteins are a unique family of viral membrane fusion proteins. These nonstructural viral proteins induce efficient cell-cell rather than virus-cell membrane fusion. We analyzed the lipid environment in which the reptilian reovirus p14 FAST protein resides to determine the influence of the cell membrane on the fusion activity of the FAST proteins. Topographical mapping of the surface of fusogenic p14-containing liposomes by atomic force microscopy under aqueous conditions revealed that p14 resides almost exclusively in thickened membrane microdomains. In transfected cells, p14 was found in both Lubrol WX-and Triton X-100-resistant membrane complexes. Cholesterol depletion …
Spinning-Black-Hole Binaries: The Orbital Hang-Up, Manuela Campanelli, Carlos O. Lousto, Y. Zlochower
Spinning-Black-Hole Binaries: The Orbital Hang-Up, Manuela Campanelli, Carlos O. Lousto, Y. Zlochower
Physics and Astronomy Faculty Publications and Presentations
We present the first fully-nonlinear numerical study of the dynamics of highly-spinning-black-hole binaries. We evolve binaries from quasicircular orbits (as inferred from post-Newtonian theory), and find that the last stages of the orbital motion of black-hole binaries are profoundly affected by their individual spins. In order to cleanly display its effects, we consider two equal-mass holes with individual spin parameters S/m2=0.757, both aligned and antialigned with the orbital angular momentum (and compare with the spinless case), and with an initial orbital period of 125M. We find that the aligned case completes three orbits and merges significantly after the antialigned case, …
Consequences Of Disk Scale Height On Lisa Confusion Noise From Close White Dwarf Binaries, M. Benacquista, K. Holley-Bockelmann
Consequences Of Disk Scale Height On Lisa Confusion Noise From Close White Dwarf Binaries, M. Benacquista, K. Holley-Bockelmann
Physics and Astronomy Faculty Publications and Presentations
Gravitational radiation from the Galactic population of close white dwarf binaries (CWDBs) is expected to produce a confusion-limited signal at the lower end of the sensitivity band of the Laser Interferometer Space Antenna (LISA). The canonical scale height of the disk population has been taken to be 90 pc for most studies of the nature of this confusion-limited signal. This estimate is probably too low, and the consequences of a more realistic scale height are investigated with a model of the LISA signal due to populations of CWDBs with different scale heights. If the local space density of CWDBs is …
Measurement Of Orbital Decay In The Double Neutron Star Binary Psr B2127+11c, B. A. Jacoby, P. B. Cameron, F. A. Jenet, S. B. Anderson, R. N. Murty, S. R. Kulkarni
Measurement Of Orbital Decay In The Double Neutron Star Binary Psr B2127+11c, B. A. Jacoby, P. B. Cameron, F. A. Jenet, S. B. Anderson, R. N. Murty, S. R. Kulkarni
Physics and Astronomy Faculty Publications and Presentations
We report the direct measurement of orbital period decay in the double neutron star pulsar system PSR B2127 + 11C in the globular cluster M15 at the rate of (-3.95 ± 0.13) × 10-12, consistent with the prediction of general relativity at the ∼3% level. We find the pulsar mass to be mp = 1.358 ± 0.010 M⊙ and the companion mc = 1.354 ± 0.010 M⊙. We also report long-term pulse timing results for the pulsars PSR B2127+11A and PSR B2127+11B, including confirmation of the cluster proper motion.
Joint Ligo And Tama300 Search For Gravitational Waves From Inspiralling Neutron Star Binaries, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Cristina V. Torres
Joint Ligo And Tama300 Search For Gravitational Waves From Inspiralling Neutron Star Binaries, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an intercollaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3M⊙ of 49 per year per Milky Way equivalent galaxy at a 90% confidence level. The methods developed during this search will find application in …
Tomographic Approach To Resolving The Distribution Of Lisa Galactic Binaries, Soumya Mohanty, Rajesh K. Nayak
Tomographic Approach To Resolving The Distribution Of Lisa Galactic Binaries, Soumya Mohanty, Rajesh K. Nayak
Physics and Astronomy Faculty Publications and Presentations
The space based gravitational wave detector LISA (Laser Interferometer Space Antenna) is expected to observe a large population of Galactic white dwarf binaries whose collective signal is likely to dominate instrumental noise at observational frequencies in the range 10−4 to 10−3 Hz. The motion of LISA modulates the signal of each binary in both frequency and amplitude—the exact modulation depending on the source direction and frequency. Starting with the observed response of one LISA interferometer and assuming only Doppler modulation due to the orbital motion of LISA, we show how the distribution of the entire binary population in frequency and …
Accurate Evolutions Of Orbiting Black-Hole Binaries Without Excision, M. Campanelli, C. O. Lousto, P. Marronetti, Z. Zlochower
Accurate Evolutions Of Orbiting Black-Hole Binaries Without Excision, M. Campanelli, C. O. Lousto, P. Marronetti, Z. Zlochower
Physics and Astronomy Faculty Publications and Presentations
We present a new algorithm for evolving orbiting black-hole binaries that does not require excision or a corotating shift. Our algorithm is based on a novel technique to handle the singular puncture conformal factor. This system, based on the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein’s equations, when used with a ‘‘precollapsed’’ initial lapse, is nonsingular at the start of the evolution and remains nonsingular and stable provided that a good choice is made for the gauge. As a test case, we use this technique to fully evolve orbiting black-hole binaries from near the innermost stable circular orbit regime. We show fourth-order convergence …
Relativistic Binaries In Globular Clusters, Matthew J. Benacquista
Relativistic Binaries In Globular Clusters, Matthew J. Benacquista
Physics and Astronomy Faculty Publications and Presentations
The galactic population of globular- cluster's are old, dense star systems, with a typical cluster containing 104 -107 stars. As an old population of stars, globular clusters contain many collapsed and degenerate objects. As a dense population of stars, globular clusters are the scene of many interesting close dynamical interactions between stars. These dynamical interactions can alter the evolution of individual stars and can produce tight binary systems containing one or- two compact objects. In this review, we discuss the theoretical models of globular cluster evolution and binary evolution, techniques for simulating this evolution which lead to relativistic binaries, and …
Search For Gravitational Waves From Binary Black Hole Inspirals In Ligo Data, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres
Search For Gravitational Waves From Binary Black Hole Inspirals In Ligo Data, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20M⊙. Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that could be identified as gravitational waves in the 385.6 hours of data that we searched.
Ferromagnetic Resonance Investigations On Ga0.965mn0.035as Film, S. Balascuta, X. Liu, D. V. Baxter, J. Carini, T. Wojtowicz, Y. Sasaki, J. Furdyna, Mircea Chipara
Ferromagnetic Resonance Investigations On Ga0.965mn0.035as Film, S. Balascuta, X. Liu, D. V. Baxter, J. Carini, T. Wojtowicz, Y. Sasaki, J. Furdyna, Mircea Chipara
Physics and Astronomy Faculty Publications and Presentations
Ferromagnetic resonance studies of the temperature dependence of magnetic anisotropies in a Ga0.965Mn0.035As film between 5 and 40K are reported. The in-plane and out-of-the-plane angular dependences of the resonance field were analyzed within the Landau-Lifshitz-Gilbert approach. The second- and fourth-order magnetic anisotropy energies were derived. The temperature dependence of magnetization and of magnetic anisotropy were studied by superconducting quantum interference device and ferromagnetic resonance.
Electrical Pulse Formation During High Temperature Reaction Between Ni And Al, Mona Setoodeh, Karen S. Martirosyan, Dan Luss
Electrical Pulse Formation During High Temperature Reaction Between Ni And Al, Mona Setoodeh, Karen S. Martirosyan, Dan Luss
Physics and Astronomy Faculty Publications and Presentations
An electric voltage pulse (duration of about 2ms) with an amplitude of up to 0.6V was generated during the reaction between nickel and aluminum powders by a high temperature moving reaction front. The electrical signal formed during the initial stages of the combustion was annihilated before the moving front attained its maximum temperature. The voltage amplitude and combustion temperature depended on the particle size of the reactants as well as the Al to Ni ratio in the reactant mixture, and their largest values were attained for a mixture containing 27–31.5wt% Al. The combustion temperature increased when smaller Al particles were …
The Lazarus Project. Ii. Spacelike Extraction With The Quasi-Kinnersley Tetrad, Manuela Campanelli, Bernard Kelly, Carlos O. Lousto
The Lazarus Project. Ii. Spacelike Extraction With The Quasi-Kinnersley Tetrad, Manuela Campanelli, Bernard Kelly, Carlos O. Lousto
Physics and Astronomy Faculty Publications and Presentations
The Lazarus project was designed to make the most of limited 3D binary black-hole simulations, through the identification of perturbations at late times, and subsequent evolution of the Weyl scalar Ψ4 via the Teukolsky formulation. Here we report on new developments, employing the concept of the “quasi-Kinnersley” (transverse) frame, valid in the full nonlinear regime, to analyze late-time numerical space-times that should differ only slightly from Kerr. This allows us to extract the essential information about the background Kerr solution, and through this, to identify the radiation present. We explicitly test this procedure with full-numerical evolutions of Bowen-York data for …
Relativistic Three-Body Effects In Black Hole Coalescence, Manuela Campanelli, Miranda Dettwyler, Mark Hannam, Carlos O. Lousto
Relativistic Three-Body Effects In Black Hole Coalescence, Manuela Campanelli, Miranda Dettwyler, Mark Hannam, Carlos O. Lousto
Physics and Astronomy Faculty Publications and Presentations
Three-body interactions are expected to be common in globular clusters and in galactic cores hosting supermassive black holes. We consider an equal-mass binary black hole system in the presence of a third black hole. Using numerically generated binary black hole initial data sets, and first and second-order post-Newtonian (1PN and 2PN) techniques, we find that the presence of the third black hole has nonnegligible relativistic effects on the location of the binary’s innermost stable circular orbit (ISCO), and that these effects arise at 2PN order. For a stellar-mass black hole binary in orbit about a supermassive black hole, the massive …