Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 15 of 15
Full-Text Articles in Physical Sciences and Mathematics
Numerical Integration Of The Teukolsky Equation In The Time Domain, Enrique Pazos-Avalos, Carlos O. Lousto
Numerical Integration Of The Teukolsky Equation In The Time Domain, Enrique Pazos-Avalos, Carlos O. Lousto
Physics and Astronomy Faculty Publications and Presentations
We present a fourth-order convergent, (2+1)-dimensional, numerical formalism to solve the Teukolsky equation in the time domain. Our approach is first to rewrite the Teukolsky equation as a system of first-order differential equations. In this way we get a system that has the form of an advection equation. This is then used in combination with a series expansion of the solution in powers of time. To obtain a fourth-order scheme we kept terms up to fourth derivative in time and use the advectionlike system of differential equations to substitute the temporal derivatives by spatial derivatives. This scheme is applied to …
Α-Enhanced Integrated Lick/Ids Spectral Indices And Milky Way And M31 Globular Clusters And Early-Type Galaxies, Hyun Chul Lee, Guy Worthey
Α-Enhanced Integrated Lick/Ids Spectral Indices And Milky Way And M31 Globular Clusters And Early-Type Galaxies, Hyun Chul Lee, Guy Worthey
Physics and Astronomy Faculty Publications and Presentations
All 25 Lick/IDS spectral indices have been computed for the integrated light of simple stellar populations over broad ranges of age and metallicity and with effects from horizontal-branch stars fully implemented. Our models employ α-enhanced isochrones at the sub-solar metallicity regime, but solar-scaled ones at solar and super-solar metallicity. We have also employed the updated response functions of Houdashelt et al. at the solar and super-solar metallicity regime, so that we could assess the light-element enhancement phenomena seen from metal-rich early-type galaxies. For Balmer indices a significant response was noted for Hγ and Hδ when α-elements are enhanced, but Hβ …
Pulsar Timing And The Detection Of Black Hole Binary Systems In Globular Clusters, Fredrick A. Jenet, Teviet Creighton, Andrea Lommen
Pulsar Timing And The Detection Of Black Hole Binary Systems In Globular Clusters, Fredrick A. Jenet, Teviet Creighton, Andrea Lommen
Physics and Astronomy Faculty Publications and Presentations
The possible existence of intermediate-mass binary black holes (IMBBHs) in globular clusters (GCs) offers us a unique geometry in which to detect spacetime oscillations. For certain pulsar-IMBBH configurations possible within a GC, the usual far-field plane wave approximation for the IMBBH metric perturbation severely underestimates the induced pulse time-of-arrival (TOA) fluctuations. In this Letter, the expected TOA fluctuations induced by an IMBBH lying close to the line of sight between a pulsar and the Earth are calculated for the first time. For an IMBBH consisting of 10 and 103 M⊙ components, a 10 yr orbital period, and located 0.1 lt-yr …
Detecting The Stochastic Gravitational Wave Background Using Pulsar Timing, Fredrick A. Jenet, George B. Hobbs, K. J. Lee, Richard N. Manchester
Detecting The Stochastic Gravitational Wave Background Using Pulsar Timing, Fredrick A. Jenet, George B. Hobbs, K. J. Lee, Richard N. Manchester
Physics and Astronomy Faculty Publications and Presentations
The direct detection of gravitational waves is a major goal of current astrophysics. We provide details of a new method for detecting a stochastic background of gravitational waves using pulsar timing data. Our results show that regular timing observations of 40 pulsars each with a timing accuracy of 100 ns will be able to make a direct detection of the predicted stochastic background from coalescing black holes within 5 years. With an improved prewhitening algorithm, or if the background is at the upper end of the predicted range, a significant detection should be possible with only 20 pulsars. © 2005. …
Upper Limits On A Stochastic Background Of Gravitational Waves, B. P. Abbott, R. Abbott, Mario C. Diaz, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
Upper Limits On A Stochastic Background Of Gravitational Waves, B. P. Abbott, R. Abbott, Mario C. Diaz, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
The Laser Interferometer Gravitational-Wave Observatory has performed a third science run with much improved sensitivities of all three interferometers. We present an analysis of approximately 200 hours of data acquired during this run, used to search for a stochastic background of gravitational radiation. We place upper bounds on the energy density stored as gravitational radiation for three different spectral power laws. For the flat spectrum, our limit of Ω0
Upper Limits On Gravitational Wave Bursts In Ligo’S Second Science Run, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres
Upper Limits On Gravitational Wave Bursts In Ligo’S Second Science Run, 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 perform a search for gravitational wave bursts using data from the second science run of the LIGO detectors, using a method based on a wavelet time-frequency decomposition. This search is sensitive to bursts of duration much less than a second and with frequency content in the 100–1100 Hz range. It features significant improvements in the instrument sensitivity and in the analysis pipeline with respect to the burst search previously reported by LIGO. Improvements in the search method allow exploring weaker signals, relative to the detector noise floor, while maintaining a low false alarm rate, O ( 0.1 ) μ …
Search For Gravitational Waves From Primordial Black Hole Binary Coalescences In The Galactic Halo, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
Search For Gravitational Waves From Primordial Black Hole Binary Coalescences In The Galactic Halo, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole binary coalescence with component masses in the range 0.2–1.0M⊙. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing nonspinning black holes with masses in the range 0.2–1.0M⊙, we place an observational upper limit on the rate of primordial black hole coalescence of 63 per year …
Search For Gravitational Waves Associated With The Gamma Ray Burst Grb030329 Using The Ligo Detectors, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres
Search For Gravitational Waves Associated With The Gamma Ray Burst Grb030329 Using The Ligo Detectors, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We have performed a search for bursts of gravitational waves associated with the very bright gamma ray burst GRB030329, using the two detectors at the LIGO Hanford Observatory. Our search covered the most sensitive frequency range of the LIGO detectors (approximately 80–−2048 Hz), and we specifically targeted signals shorter than ≃150 ms. Our search algorithm looks for excess correlated power between the two interferometers and thus makes minimal assumptions about the gravitational waveform. We observed no candidates with gravitational-wave signal strength larger than a predetermined threshold. We report frequency-dependent upper limits on the strength of the gravitational waves associated with …
Upper Limits From The Ligo And Tama Detectors On The Rate Of Gravitational-Wave Bursts, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Cristina V. Torres
Upper Limits From The Ligo And Tama Detectors On The Rate Of Gravitational-Wave Bursts, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We report on the first joint search for gravitational waves by the TAMA and LIGO collaborations. We looked for millisecond-duration unmodeled gravitational-wave bursts in 473 hr of coincident data collected during early 2003. No candidate signals were found. We set an upper limit of 0.12 events per day on the rate of detectable gravitational-wave bursts, at 90% confidence level. From software simulations, we estimate that our detector network was sensitive to bursts with root-sum-square strain amplitude above approximately 1–3×10−19 Hz−1/2 in the frequency band 700-2000 Hz. We describe the details of this collaborative search, with particular emphasis on its advantages …
Search For Gravitational Waves From Galactic And Extra-Galactic Binary Neutron Stars, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
Search For Gravitational Waves From Galactic And Extra-Galactic Binary Neutron Stars, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We use 373 hours (≈15 days) of data from the second science run of the LIGO gravitational-wave detectors to search for signals from binary neutron star coalescences within a maximum distance of about 1.5 Mpc, a volume of space which includes the Andromeda Galaxy and other galaxies of the Local Group of galaxies. This analysis requires a signal to be found in data from detectors at the two LIGO sites, according to a set of coincidence criteria. The background (accidental coincidence rate) is determined from the data and is used to judge the significance of event candidates. No inspiral gravitational-wave …
Response Of Test Masses To Gravitational Waves In The Local Lorentz Gauge, Malik Rakhmanov
Response Of Test Masses To Gravitational Waves In The Local Lorentz Gauge, Malik Rakhmanov
Physics and Astronomy Faculty Publications and Presentations
The local Lorentz gauge represents a natural coordinate frame for an observer to analyze the effect of gravitational waves on detectors, and has been widely used to describe the response of resonant bars. Its application to laser interferometers has thus far been restricted to the long-wavelength regime, in which the separation between the test masses is much less than the wavelength of the gravitational waves. In this paper we show that the local Lorentz gauge can be used for calculations of geodesic deviations of the masses even when their separation is comparable to or greater than the wavelength of the …
Phase Effects In The Diffraction Of Light: Beyond The Grating Equation, Stacy Wise, V. Quetschke, A. J. Deshpande, G. Mueller, D. H. Reitze, D. B. Tanner, B. F. Whiting, Y. Chen
Phase Effects In The Diffraction Of Light: Beyond The Grating Equation, Stacy Wise, V. Quetschke, A. J. Deshpande, G. Mueller, D. H. Reitze, D. B. Tanner, B. F. Whiting, Y. Chen
Physics and Astronomy Faculty Publications and Presentations
Diffraction gratings affect the absolute phase of light in a way that is not obvious from the usual derivation of optical paths using the grating equation. For example, consider light which encounters first one and then the second of two parallel gratings. If one grating is moved parallel to its surface, the phase of the light diffracted from the grating pair is shifted by 2π each time the grating is moved by one grating constant, even though the geometric path length is not altered by the motion. This additional phase shift must be included when incorporating diffraction gratings in interferometers.
Electric-Field Generated By The Combustion Of Titanium In Nitrogen, Karen S. Martirosyan, Mona Setoodeh, Dan Luss
Electric-Field Generated By The Combustion Of Titanium In Nitrogen, Karen S. Martirosyan, Mona Setoodeh, Dan Luss
Physics and Astronomy Faculty Publications and Presentations
A short temporal electrical impulse (duration of 30–150ms) was generated during the nitridation of mixtures of titanium and titanium nitride by a high temperature moving reaction front. The maximum voltage and current were generated in the combustion front region, in which the conversion of Ti to TiN was incomplete. The electric field (voltage up to 2V and current up to 60mA) decayed and vanished before the maximum combustion temperature was attained. The generation of an electric field during a rapid high-temperature nitridation is most probably due to the different diffusion velocities of charge carriers through the growing titanium nitride shell …
First All-Sky Upper Limits From Ligo On The Strength Of Periodic Gravitational Waves Using The Hough Transform, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
First All-Sky Upper Limits From Ligo On The Strength Of Periodic Gravitational Waves Using The Hough Transform, B. P. Abbott, R. Abbott, W. G. Anderson, Mario C. Diaz, Wm. R. Johnston, Soma Mukherjee, Soumya Mohanty, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We perform a wide parameter-space search for continuous gravitational waves over the whole sky and over a large range of values of the frequency and the first spin-down parameter. Our search method is based on the Hough transform, which is a semicoherent, computationally efficient, and robust pattern recognition technique. We apply this technique to data from the second science run of the LIGO detectors and our final results are all-sky upper limits on the strength of gravitational waves emitted by unknown isolated spinning neutron stars on a set of narrow frequency bands in the range 200–400 Hz. The best upper …
Limits On Gravitational-Wave Emission From Selected Pulsars Using Ligo Data, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres
Limits On Gravitational-Wave Emission From Selected Pulsars Using Ligo Data, B. P. Abbott, R. Abbott, Mario C. Diaz, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres
Physics and Astronomy Faculty Publications and Presentations
We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10−24. These strain limits translate into limits on the equatorial ellipticities of the pulsars, …