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Articles 1 - 18 of 18
Full-Text Articles in Physical Sciences and Mathematics
The Nanograv 12.5 Yr Data Set: Observations And Narrowband Timing Of 47 Millisecond Pulsars, Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Keeisi Caballero, Richard S. Camuccio, Yhamil Garcia
The Nanograv 12.5 Yr Data Set: Observations And Narrowband Timing Of 47 Millisecond Pulsars, Md F. Alam, Zaven Arzoumanian, Paul T. Baker, Harsha Blumer, Keith E. Bohler, Keeisi Caballero, Richard S. Camuccio, Yhamil Garcia
Physics and Astronomy Faculty Publications and Presentations
We present time-of-arrival (TOA) measurements and timing models of 47 millisecond pulsars observed from 2004 to 2017 at the Arecibo Observatory and the Green Bank Telescope by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav). The observing cadence was three to four weeks for most pulsars over most of this time span, with weekly observations of six sources. These data were collected for use in low-frequency gravitational wave searches and for other astrophysical purposes. We detail our observational methods and present a set of TOA measurements, based on "narrowband" analysis, in which many TOAs are calculated within narrow radio-frequency …
A Conceptual Model To Explain Dark Matter And Dark Energy, Jonathan Blackledge
A Conceptual Model To Explain Dark Matter And Dark Energy, Jonathan Blackledge
Articles
This paper considers a conceptual model that attempts to explain ‘Dark Matter’ and‘Dark Energy’. The model is based on considering a gravitational field to be the result of a mass (aHiggs field) scattering pre-existing cosmic background space-time waves or ‘Uber-waves’. The term‘Uber’ is used to denote an outstanding or supreme example of a particular kind of gravitationalwave with cosmic-scale wavelengths that are far in excess of those associated with the gravitationalwaves generated by accelerating masses. Such waves are taken to be the very lowest frequencycomponents associated with the spectrum of space-time waves generated by the ‘Big Bang’ andare supported by …
Measurements And Mitigation Of Scattered Light Noise In Ligo, Corey Daniel Austin
Measurements And Mitigation Of Scattered Light Noise In Ligo, Corey Daniel Austin
LSU Doctoral Dissertations
The Advanced LIGO (aLIGO) detectors use 1064 nm lasers to measure the tiny fluctuations in spacetime that occur when gravitational waves pass through the earth. LIGO makes use of advanced coating methods and materials to limit the amount of light that scatters from the main beam, but some amount of light does scatter. This stray light can interact with surfaces inside the interferometer that are not seismically isolated and then recombine with the main beam, introducing excess noise into the gravitational wave channel. This thesis reviews the methods for modeling scattered light with ray tracing software and analytical models, for …
Gravitational-Wave Constraints On The Equatorial Ellipticity Of Millisecond Pulsars, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, W. H. Wang
Gravitational-Wave Constraints On The Equatorial Ellipticity Of Millisecond Pulsars, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, W. H. Wang
Physics and Astronomy Faculty Publications and Presentations
We present a search for continuous gravitational waves from five radio pulsars, comprising three recycled pulsars (PSR J0437−4715, PSR J0711−6830, and PSR J0737−3039A) and two young pulsars: the Crab pulsar (J0534+2200) and the Vela pulsar (J0835−4510). We use data from the third observing run of Advanced LIGO and Virgo combined with data from their first and second observing runs. For the first time we are able to match (for PSR J0437−4715) or surpass (for PSR J0711−6830) the indirect limits on gravitational-wave emission from recycled pulsars inferred from their observed spin-downs, and constrain their equatorial ellipticities to be less than 10−8 …
Gw190521: A Binary Black Hole Merger With A Total Mass Of 150 M⊙, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Gw190521: A Binary Black Hole Merger With A Total Mass Of 150 M⊙, R. Abbott, T. D. Abbott, Marco Cavaglia, For Full List Of Authors, See Publisher's Website.
Physics Faculty Research & Creative Works
On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85+21−14 M⊙ and 66+17−18 M⊙ (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only …
Prospects For Observing And Localizing Gravitational-Wave Transients With Advanced Ligo, Advanced Virgo And Kagra, B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, T. Akutsu, B. Allen, A. Allocca, P. A. Altin, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Ando, S. Appert, K. Arai, A. Araya, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, W. H. Wang, A. K. Zadrozny
Prospects For Observing And Localizing Gravitational-Wave Transients With Advanced Ligo, Advanced Virgo And Kagra, B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, T. Akutsu, B. Allen, A. Allocca, P. A. Altin, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Ando, S. Appert, K. Arai, A. Araya, Teviet Creighton, Mario C. Diaz, S. Mukherjee, V. Quetschke, Malik Rakhmanov, K. E. Ramirez, Satzhan Sitmukhambetov, Robert Stone, D. Tuyenbayev, W. H. Wang, A. K. Zadrozny
Physics and Astronomy Faculty Publications and Presentations
We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of …
Binary Neutron Star Mergers: Testing Ejecta Models For High Mass-Ratios, Allen Murray
Binary Neutron Star Mergers: Testing Ejecta Models For High Mass-Ratios, Allen Murray
The Journal of Purdue Undergraduate Research
Neutron stars are extremely dense stellar corpses which sometimes exist in orbiting pairs known as binary neutron star (BNS) systems. The mass ratio (q) of a BNS system is defined as the mass of the heavier neutron star divided by the mass of the lighter neutron star. Over time the neutron stars will inspiral toward one another and produce a merger event. Although rare, these events can be rich sources of observational data due to their many electromagnetic emissions as well as the gravitational waves they produce. The ability to extract physical information from such observations relies heavily on numerical …
Searching For Pulsars Using The Long Wavelength Array Telescope, Keeisi A. Caballero Valdez
Searching For Pulsars Using The Long Wavelength Array Telescope, Keeisi A. Caballero Valdez
Theses and Dissertations
Radio pulsars are fascinating celestial objects known to display both periodic and transient behavior. Pulsars are characterized by narrow electromagnetic radiation beams which restrict the number of pulsars visible from Earth due to the necessary alignment of the radiation beam across an observer’s line of sight. Pulsars are useful tools for a broad range of applications and provide important information about the process of stellar evolution, tests for relativistic theories of gravity and the search for low-frequency gravitational waves. Over 2,500 pulsars have been observed since their initial discovery in 1967 but the search for these objects is continuously warranted. …
Merging Neutron Star And Black Hole Binaries: Inference Of Their Parameters And Simulations Of Their Formation And Fate, Soumi De
Dissertations - ALL
In recent years, the growing numbers of black hole and neutron star merger candidates observed by the Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory) and Virgo gravitational-wave observatories are rapidly expanding the frontiers of astrophysics. The observations enable (i) direct measurements of properties of these compact objects with information extraction from the gravitational-wave data, and seek the understanding of (ii) mechanisms by which the close compact object binaries come into existence and (iii) the astrophysical processes that take place after they merge. This thesis presents work on all these three fronts (i) We present measurements of properties of the binary neutron …
Searching For Optical Counterparts To Gravitational Waves, Richard Camuccio
Searching For Optical Counterparts To Gravitational Waves, Richard Camuccio
Theses and Dissertations
The era of multi-messenger astronomy has begun. The coordinated activities of multiple, distinct observatories play a critical role in both responding to astrophysical transients and building a more comprehensive interpretation otherwise inaccessible to individual observations. The Transient Robotic Observatory of the South (TOROS) Collaboration has a global network of instruments capable of responding to several transient targets of opportunity. The purpose of this thesis is to demonstrate how optical observatories with small fields of view (degree) can follow up and observe astrophysical transients. TOROS facilities responded to three unique gravitational wave events during the second and third observational campaigns of …
Harbingers Of Exotic Transients: The Electromagnetic Follow-Up Of Gravitational-Wave Transients & Transient Rates, Deep Chatterjee
Harbingers Of Exotic Transients: The Electromagnetic Follow-Up Of Gravitational-Wave Transients & Transient Rates, Deep Chatterjee
Theses and Dissertations
Gravitational waves (GWs) provide a unique view of the universe. They directly probe the extreme gravity and extreme matter of compact objects like black holes (BHs) and neutron stars (NSs) which is not always possible from traditional electromagnetic (EM) wave astronomy. The cataclysmic coalescence of compact object binaries is one of the loudest individual sources of GWs that can be detected by the Laser Interferometer Gravitational wave Observatory (LIGO) and the Virgo Observatory. If one of the component is a NS, there is a possibility that the merger is bright in the EM spectrum. The relativistic astrophysics could launch a …
Towards A Real-Time Fully-Coherent All-Sky Search For Gravitational Waves From Compact Binary Coalescences Using Particle Swarm Optimization, M. E. Normandin, Soumya Mohanty
Towards A Real-Time Fully-Coherent All-Sky Search For Gravitational Waves From Compact Binary Coalescences Using Particle Swarm Optimization, M. E. Normandin, Soumya Mohanty
Physics and Astronomy Faculty Publications and Presentations
While a fully-coherent all-sky search is known to be optimal for detecting gravitational wave signals from compact binary coalescences, its high computational cost has limited current searches to less sensitive coincidence-based schemes. Following up on previous work that has demonstrated the effectiveness of particle swarm optimization (PSO) in reducing the computational cost of this search, we present an implementation that achieves near real-time computational speed. This is achieved by combining the search efficiency of PSO with a significantly revised and optimized numerical implementation of the underlying mathematical formalism along with additional multithreaded parallelization layers in a distributed computing framework. For …
Fast Radio Bursts From Interacting Binary Neutron Star Systems, Bing Zhang
Fast Radio Bursts From Interacting Binary Neutron Star Systems, Bing Zhang
Physics & Astronomy Faculty Research
Recent observations of repeating fast radio bursts (FRBs) suggest that some FRBs reside in an environment consistent with that of binary neutron star (BNS) mergers. The bursting rate for repeaters could be very high and the emission site is likely from a magnetosphere. We discuss a hypothesis of producing abundant repeating FRBs in BNS systems. Decades to centuries before a BNS system coalesces, the magnetospheres of the two neutron stars start to interact relentlessly. Abrupt magnetic reconnection accelerates particles, which emit coherent radio waves in bunches via curvature radiation. FRBs are detected as these bright radiation beams point toward Earth. …
Relation Between Gravitational Mass And Baryonic Mass For Non-Rotating And Rapidly Rotating Neutron Stars, He Gao, Shun-Ke Ai, Zhou-Jian Cao, Bing Zhang, Zhen-Yu Zhu, Ang Li, Nai-Bo Zhang, Andreas Bauswein
Relation Between Gravitational Mass And Baryonic Mass For Non-Rotating And Rapidly Rotating Neutron Stars, He Gao, Shun-Ke Ai, Zhou-Jian Cao, Bing Zhang, Zhen-Yu Zhu, Ang Li, Nai-Bo Zhang, Andreas Bauswein
Physics & Astronomy Faculty Research
With a selected sample of neutron star (NS) equations of state (EOSs) that are consistent with the current observations and have a range of maximum masses, we investigate the relations between NS gravitational mass Mg and baryonic mass Mb, and the relations between the maximum NS mass supported through uniform rotation (Mmax) and that of nonrotating NSs (MTOV). We find that for an EOS-independent quadratic, universal transformation formula (Mb=Mg+A×M2g)(Mb=Mg+A×Mg2), the best-fit A value is 0.080 for non-rotating NSs, 0.064 for maximally rotating NSs, and 0.073 when NSs with arbitrary rotation are considered. The residual error of the transformation is ∼ …
A Guide To Ligo–Virgo Detector Noise And Extraction Of Transient Gravitational-Wave Signals, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration
A Guide To Ligo–Virgo Detector Noise And Extraction Of Transient Gravitational-Wave Signals, Tiffany Summerscales, Ligo Scientific Collaboration And The Virgo Collaboration
Faculty Publications
The LIGO Scientific Collaboration and the Virgo Collaboration have cataloged eleven confidently detected gravitational-wave events during the first two observing runs of the advanced detector era. All eleven events were consistent with being from well-modeled mergers between compact stellarmass objects: black holes or neutron stars. The data around the time of each of these events have been made publicly available through the gravitationalwave open science center. The entirety of the gravitational-wave strain data from the first and second observing runs have also now been made publicly available. There is considerable interest among the broad scientific community in understanding the data …
A Nonminimally Coupled, Conformally Extended Einstein-Maxwell Theory Of Pp-Waves, Dündar Teki̇n Dereli̇, Yorgo Şeni̇koğlu
A Nonminimally Coupled, Conformally Extended Einstein-Maxwell Theory Of Pp-Waves, Dündar Teki̇n Dereli̇, Yorgo Şeni̇koğlu
Turkish Journal of Physics
A nonminimal coupling of Weyl curvatures to electromagnetic fields is considered in Brans-Dicke-Maxwell theory. The gravitational field equations are formulated in a Riemannian spacetime where the spacetime torsion is constrained to zero by the method of Lagrange multipliers in the language of exterior differential forms. The significance and ramifications of nonminimal couplings to gravity are examined in a pp-wave spacetime.
Numerical Analysis And Gravity, Tyler D. Knowles
Numerical Analysis And Gravity, Tyler D. Knowles
Graduate Theses, Dissertations, and Problem Reports
In this dissertation we apply techniques of numerical analysis to current questions related to understanding gravity. The first question is that of sources of gravitational waves: how can we accurately determine the intrinsic physical parameters of a binary system whose late inspiral and merger was detected by the Laser Interferometer Gravitational-Wave Observatory. In particular, state-of-the-art algorithms for producing theoretical waveforms are as many as three orders of magnitude too slow for timely analysis. We show that direct software optimization produces a two order of magnitude speedup. We also describe documentation efforts undertaken so that the software may be rewritten to …
Modeling The Galactic Compact Binary Neutron Star Population And Studying The Double Pulsar System, Nihan Pol
Modeling The Galactic Compact Binary Neutron Star Population And Studying The Double Pulsar System, Nihan Pol
Graduate Theses, Dissertations, and Problem Reports
Binary neutron star (BNS) systems consisting of at least one neutron star provide an avenue for testing a broad range of physical phenomena ranging from tests of General Relativity to probing magnetospheric physics to understanding the behavior of matter in the densest environments in the Universe. Ultra-compact BNS systems with orbital periods less than few tens of minutes emit gravitational waves with frequencies ~mHz and are detectable by the planned space-based Laser Interferometer Space Antenna (LISA), while merging BNS systems produce a chirping gravitational wave signal that can be detected by the ground-based Laser Interferometer Gravitational-Wave Observatory (LIGO). Thus, BNS …