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Search Results: 1 - 10 of 200692 matches for " P. Shawhan "
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Feasibility of measuring the Shapiro time delay over meter-scale distances
S. Ballmer,S. Márka,P. Shawhan
Physics , 2009, DOI: 10.1088/0264-9381/27/18/185018
Abstract: The time delay of light as it passes by a massive object, first calculated by Shapiro in 1964, is a hallmark of the curvature of space-time. To date, all measurements of the Shapiro time delay have been made over solar-system distance scales. We show that the new generation of kilometer-scale laser interferometers being constructed as gravitational wave detectors, in particular Advanced LIGO, will in principle be sensitive enough to measure variations in the Shapiro time delay produced by a suitably designed rotating object placed near the laser beam. We show that such an apparatus is feasible (though not easy) to construct, present an example design, and calculate the signal that would be detectable by Advanced LIGO. This offers the first opportunity to measure space-time curvature effects on a laboratory distance scale.
Gravitational-wave astronomy: Observational results and their impact
Peter S. Shawhan
Physics , 2010, DOI: 10.1088/0264-9381/27/8/084017
Abstract: The successful construction and operation of highly sensitive gravitational-wave detectors is an achievement to be proud of, but the detection of actual signals is still around the corner. Even so, null results from recent searches have told us some interesting things about the objects that live in our universe, so it can be argued that the era of gravitational-wave astronomy has already begun. In this article I review several of these results and discuss what we have learned from them. I then look into the not-so-distant future and predict some ways in which the detection of gravitational-wave signals will shape our knowledge of astrophysics and transform the field.
A New Waveform Consistency Test for Gravitational Wave Inspiral Searches
Peter Shawhan,Evan Ochsner
Physics , 2004, DOI: 10.1088/0264-9381/21/20/018
Abstract: Searches for binary inspiral signals in data collected by interferometric gravitational wave detectors utilize matched filtering techniques. Although matched filtering is optimal in the case of stationary Gaussian noise, data from real detectors often contains "glitches" and episodes of excess noise which cause filter outputs to ring strongly. We review the standard \chi^2 statistic which is used to test whether the filter output has appropriate contributions from several different frequency bands. We then propose a new type of waveform consistency test which is based on the time history of the filter output. We apply one such test to the data from the first LIGO science run and show that it cleanly distinguishes between true inspiral waveforms and large-amplitude false signals which managed to pass the standard \chi^2 test.
Prospects for joint radio telescope and gravitational wave searches for astrophysical transients
V. Predoi,J. Clark,T. Creighton,E. Daw,S. Fairhurst,I. S. Heng,J. Kanner,T. Regimbau,P. Shawhan,X. Siemens,P. Sutton,A. Vecchio,D. White,G. Woan
Physics , 2009, DOI: 10.1088/0264-9381/27/8/084018
Abstract: The radio skies remain mostly unobserved when it comes to transient phenomena. The direct detection of gravitational waves will mark a major milestone of modern astronomy, as an entirely new window will open on the universe. Two apparently independent phenomena can be brought together in a coincident effort that has the potential to boost both searches. In this paper we will outline the scientific case that stands behind these future joint observations and will describe the methods that might be used to conduct the searches and analyze the data. The targeted sources are binary systems of compact objects, known to be strong candidate sources for gravitational waves. Detection of transients coincident in these two channels would be a significant smoking gun for first direct detection of gravitational waves, and would open up a new field for characterization of astrophysical transients involving massive compact objects.
Vetoes for Inspiral Triggers in LIGO Data
Nelson Christensen,Peter Shawhan,Gabriela González,For the LIGO Scientific Collaboration
Physics , 2004, DOI: 10.1088/0264-9381/21/20/017
Abstract: Presented is a summary of studies by the LIGO Scientific Collaboration's Inspiral Analysis Group on the development of possible vetoes to be used in evaluation of data from the first two LIGO science data runs. Numerous environmental monitor signals and interferometer control channels have been analyzed in order to characterize the interferometers' performance. The results of studies on selected data segments are provided in this paper. The vetoes used in the compact binary inspiral analyses of LIGO's S1 and S2 science data runs are presented and discussed.
Rapid alerts for following up gravitational wave event candidates
Peter S. Shawhan,for the LIGO Scientific Collaboration,Virgo Collaboration
Physics , 2012, DOI: 10.1117/12.926372
Abstract: Gravitational waves carry unique information about high-energy astrophysical events such as the inspiral and merger of neutron stars and black holes, core collapse in massive stars, and other sources. Large gravitational wave (GW) detectors utilizing exquisitely sensitive laser interferometry--namely, LIGO in the United States and GEO 600 and Virgo in Europe--have been successfully operated in recent years and are currently being upgraded to greatly improve their sensitivities. Many signals are expected to be detected in the coming decade. Simultaneous observing with the network of GW detectors enables us to identify and localize event candidates on the sky with modest precision, opening up the possibility of capturing optical transients or other electromagnetic counterparts to confirm an event and obtain complementary information about it. We developed and implemented the first complete low-latency GW data analysis and alert system in 2009-10 and used it to send alerts to several observing partners; the system design and some lessons learned are briefly described. We discuss several operational considerations and design choices for improving this scientific capability for future observations.
Methods for Reducing False Alarms in Searches for Compact Binary Coalescences in LIGO Data
J. Slutsky,L. Blackburn,D. A. Brown,L. Cadonati,J. Cain,M. Cavaglià,S. Chatterji,N. Christensen,M. Coughlin,S. Desai,G. González,T. Isogai,E. Katsavounidis,B. Rankins,T. Reed,K. Riles,P. Shawhan,J. R. Smith,N. Zotov,J. Zweizig
Physics , 2010, DOI: 10.1088/0264-9381/27/16/165023
Abstract: The LIGO detectors are sensitive to a variety of noise transients of non-astrophysical origin. Instrumental glitches and environmental disturbances increase the false alarm rate in the searches for gravitational waves. Using times already identified when the interferometers produced data of questionable quality, or when the channels that monitor the interferometer indicated non-stationarity, we have developed techniques to safely and effectively veto false triggers from the compact binary coalescences (CBCs) search pipeline.
GR 20 Parallel Session A3: Modified Gravity
Petr Horava,Arif Mohd,Charles M. Melby-Thompson,Peter Shawhan
Physics , 2014, DOI: 10.1007/s10714-014-1720-4
Abstract: This is the contribution representing Parallel Session A3, on Modified Gravity, in the Proceedings of the GR 20 Conference (July 2013, Warszawa, Poland). It consists of three invited chapters, selected by the Session Chair (P.H.) to represent the broad spectrum of topics discussed in the Session, which ranged from theoretical and phenomenological, to experimental, observational and numerical aspects of gravity. The three chapters are "Einstein-Aether Theory: Thermodynamics of Universal Horizons" by Arif Mohd, "The Curious Case of Conformal Anomalies in Horava-Lifshitz Gravity" by Charles M. Melby-Thompson, and "Detectability of Scalar Gravitational-Wave Bursts with LIGO and Virgo" by Peter Shawhan.
Planned search for LIGO-GBM coincidence in the first advanced LIGO data run
Jordan Camp,Lindy Blackburn,Michael Briggs,Nelson Christensen,Valerie Connaughton,Leo Singer,Peter Shawhan,John Veitch
Physics , 2015,
Abstract: In the fall of 2015 the first scientific observing run (O1) of the advanced LIGO detectors will be conducted. Based on the recent commissioning progress at the LIGO Hanford and Livingston sites, the gravitational wave detector range for a neutron star binary inspiral is expected to be of order 60 Mpc. We describe here our planning for an O1 search for coincidence between a LIGO gravitational wave detection and a gamma-ray signal from the Fermi Gamma-ray Burst Monitor. Such a coincidence would constitute measurement of an electromagnetic counterpart to a gravitational wave signal, with significant corresponding scientific benefits, including revealing the central engine powering the gamma-ray burst, enhanced confidence in the event as a genuine astrophysical detection, and a determination of the relative speed of the photon and graviton.
The LSC Glitch Group : Monitoring Noise Transients during the fifth LIGO Science Run
L. Blackburn,L. Cadonati,S. Caride,S. Caudill,S. Chatterji,N. Christensen,J. Dalrymple,S. Desai,A. Di Credico,G. Ely,J. Garofoli,L. Goggin,G. González,R. Gouaty,C. Gray,A. Gretarsson,D. Hoak,T. Isogai,E. Katsavounidis,J. Kissel,S. Klimenko,R. A. Mercer,S. Mohapatra,S. Mukherjee,F. Raab,K. Riles,P. Saulson,R. Schofield,P. Shawhan,J. Slutsky,J. R. Smith,R. Stone,C. Vorvick,M. Zanolin,N. Zotov,J. Zweizig
Physics , 2008, DOI: 10.1088/0264-9381/25/18/184004
Abstract: The LIGO Scientific Collaboration (LSC) glitch group is part of the LIGO detector characterization effort. It consists of data analysts and detector experts who, during and after science runs, collaborate for a better understanding of noise transients in the detectors. Goals of the glitch group during the fifth LIGO science run (S5) included (1) offline assessment of the detector data quality, with focus on noise transients, (2) veto recommendations for astrophysical analysis and (3) feedback to the commissioning team on anomalies seen in gravitational wave and auxiliary data channels. Other activities included the study of auto-correlation of triggers from burst searches, stationarity of the detector noise and veto studies. The group identified causes for several noise transients that triggered false alarms in the gravitational wave searches; the times of such transients were identified and vetoed from the data generating the LSC astrophysical results.
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