Gravitational Wave Physics with Binary Love Relations
NASA Astrophysics Data System (ADS)
Yagi, Kent; Yunes, Nicolas
2016-03-01
Gravitational waves from the late inspiral of neutron star binaries encode rich information about their internal structure at supranuclear densities through their tidal deformabilities. However, extracting the individual tidal deformabilities of the components of a binary is challenging with future ground-based gravitational wave interferometers due to degeneracies between them. We overcome this difficulty by finding new, approximate universal relations between the individual tidal deformabilities that depend on the mass ratio of the two stars and are insensitive to their internal structure. Such relations have applications not only to gravitational wave astrophysics, but also to nuclear physics as they improve the measurement accuracy of tidal parameters. Moreover, the relations improve our ability to test extreme gravity and perform cosmology with gravitational waves emitted from neutron star binaries.
Testing Gravitational Physics with Space-based Gravitational-wave Observations
NASA Technical Reports Server (NTRS)
Baker, John G.
2011-01-01
Gravitational wave observations provide exceptional and unique opportunities for precision tests of gravitational physics, as predicted by general relativity (GR). Space-based gravitational wave measurements, with high signal-to-noise ratios and large numbers of observed events may provide the best-suited gravitational-wave observations for testing GR with unprecedented precision. These observations will be especially useful in testing the properties of gravitational waves and strong-field aspects of the theory which are less relevant in other observations. We review the proposed GR test based on observations of massive black hole mergers, extreme mass ratio inspirals, and galactic binary systems.
Exploring the Physics of Compact Objects with Gravitational-Wave Astronomy
NASA Astrophysics Data System (ADS)
Brown, Duncan
2016-03-01
The Advanced Laser Interferometer Gravitational Wave Observatory (LIGO) has recently completed its first observing run. Future observations of gravitational waves by LIGO will open a new field in astronomy. The gravitational waves radiated by binaries containing neutron stars and/or black holes contain information about strong field gravity and the properties of dense matter. In this talk I will discuss the nuclear and gravitational physics that can be learned from the observation of compact-object mergers
Gravitational wave background from Standard Model physics: qualitative features
Ghiglieri, J.; Laine, M.
2015-07-16
Because of physical processes ranging from microscopic particle collisions to macroscopic hydrodynamic fluctuations, any plasma in thermal equilibrium emits gravitational waves. For the largest wavelengths the emission rate is proportional to the shear viscosity of the plasma. In the Standard Model at T>160 GeV, the shear viscosity is dominated by the most weakly interacting particles, right-handed leptons, and is relatively large. We estimate the order of magnitude of the corresponding spectrum of gravitational waves. Even though at small frequencies (corresponding to the sub-Hz range relevant for planned observatories such as eLISA) this background is tiny compared with that from non-equilibrium sources, the total energy carried by the high-frequency part of the spectrum is non-negligible if the production continues for a long time. We suggest that this may constrain (weakly) the highest temperature of the radiation epoch. Observing the high-frequency part directly sets a very ambitious goal for future generations of GHz-range detectors.
The black hole symphony: probing new physics using gravitational waves.
Gair, Jonathan R
2008-12-13
The next decade will very likely see the birth of a new field of astronomy as we become able to directly detect gravitational waves (GWs) for the first time. The existence of GWs is one of the key predictions of Einstein's theory of general relativity, but they have eluded direct detection for the last century. This will change thanks to a new generation of laser interferometers that are already in operation or which are planned for the near future. GW observations will allow us to probe some of the most exotic and energetic events in the Universe, the mergers of black holes. We will obtain information about the systems to a precision unprecedented in astronomy, and this will revolutionize our understanding of compact astrophysical systems. Moreover, if any of the assumptions of relativity theory are incorrect, this will lead to subtle, but potentially detectable, differences in the emitted GWs. Our observations will thus provide very precise verifications of the theory in an as yet untested regime. In this paper, I will discuss what GW observations could tell us about known and (potentially) unknown physics. PMID:18812300
NASA Astrophysics Data System (ADS)
Conklin, John
2016-03-01
With the expected direct detection of gravitational waves by Advanced LIGO and pulsar timing arrays in the near future, and with the recent launch of LISA Pathfinder this can arguably be called the decade of gravitational waves. Low frequency gravitational waves in the mHz range, which can only be observed from space, provide the richest science and complement high frequency observatories on the ground. A space-based observatory will improve our understanding of the formation and growth of massive black holes, create a census of compact binary systems in the Milky Way, test general relativity in extreme conditions, and enable searches for new physics. LISA, by far the most mature concept for detecting gravitational waves from space, has consistently ranked among the nation's top priority large science missions. In 2013, ESA selected the science theme ``The Gravitational Universe'' for its third large mission, L3, under the Cosmic Visions Program, with a planned launch date of 2034. NASA has decided to join with ESA on the L3 mission as a junior partner and has recently assembled a study team to provide advice on how NASA might contribute to the European-led mission. This talk will describe these efforts and the activities of the Gravitational Wave Science Interest Group and the L3 Study Team, which will lead to the first space-based gravitational wave observatory.
Gravitational wave astronomy and cosmology
NASA Astrophysics Data System (ADS)
Hughes, Scott A.
2014-09-01
The first direct observation of gravitational waves' action upon matter has recently been reported by the BICEP2 experiment. Advanced ground-based gravitational-wave detectors are being installed. They will soon be commissioned, and then begin searches for high-frequency gravitational waves at a sensitivity level that is widely expected to reach events involving compact objects like stellar mass black holes and neutron stars. Pulsar timing arrays continue to improve the bounds on gravitational waves at nanohertz frequencies, and may detect a signal on roughly the same timescale as ground-based detectors. The science case for space-based interferometers targeting millihertz sources is very strong. The decade of gravitational-wave discovery is poised to begin. In this writeup of a talk given at the 2013 TAUP conference, we will briefly review the physics of gravitational waves and gravitational-wave detectors, and then discuss the promise of these measurements for making cosmological measurements in the near future.
Gravitational waves from gravitational collapse
Fryer, Christopher L; New, Kimberly C
2008-01-01
Gravitational wave emission from stellar collapse has been studied for nearly four decades. Current state-of-the-art numerical investigations of collapse include those that use progenitors with more realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non-axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with ground-based and space-based interferometric observatories. This review covers the entire range of stellar collapse sources of gravitational waves: from the accretion induced collapse of a white dwarf through the collapse down to neutron stars or black holes of massive stars to the collapse of supermassive stars.
Detectors of gravitational waves
NASA Astrophysics Data System (ADS)
Pizzella, G.
Gravitational waves Motion of test bodies in a g.w. field Energy carried by gravitational waves Gravitational-wave sources Spinning star Double-star systems Fall into a Schwarzschild black hole Radiation from gravitational collapse Gravitational-wave detectors The nonresonant detectors The resonant detectors Electromechnical transducers Piezoelectric ceramic The capacitor The inductor Data analysis The Brownian noise The back-action The wide-band noise, data analysis and optimization The resonant transducer The Wiener-Kolmogoroff filter The cross-section and the effective temperature The antenna bandwidth The gravitational-wave experiments in the world The laser interferometers The resonant detectors
NASA Technical Reports Server (NTRS)
Kelly, Bernard J.
2010-01-01
Einstein's General Theory of Relativity is our best classical description of gravity, and informs modern astronomy and astrophysics at all scales: stellar, galactic, and cosmological. Among its surprising predictions is the existence of gravitational waves -- ripples in space-time that carry energy and momentum away from strongly interacting gravitating sources. In my talk, I will give an overview of the properties of this radiation, recent breakthroughs in computational physics allowing us to calculate the waveforms from galactic mergers, and the prospect of direct observation with interferometric detectors such as LIGO and LISA.
NASA Astrophysics Data System (ADS)
Fontana, Giorgio
2005-02-01
There is only one experimental proof that gravitational waves exist. With such a limitation, it may seem premature to suggest the possibility that gravitational waves can became a preferred space propulsion technique. The present understanding of the problem indicates that this is not the case. The emission of gravitational waves from astrophysical sources has been confirmed by observation, the respective detection at large distance from the source is difficult and actually we have no confirmation of a successful detection. Therefore the required preliminary discovery has been already made. This opinion is enforced by many different proposals for building the required powerful gravitational wave generators that have recently appeared in the literature and discussed at conferences. It is no longer reasonable to wait for additional confirmation of the existence of gravitational waves to start a program for building generators and testing their possible application to space travel. A vast literature shows that gravitational waves can be employed for space propulsion. Gravitational wave rockets have been proposed, non-linearity of Einstein equations allows the conversion of gravitational waves to a static gravitational field and ``artificial gravity assist'' may become a new way of travelling in space-time. Different approaches to gravitational wave propulsion are reviewed and compared. Gravitational wave propulsion is also compared to traditional rocket propulsion and an undeniable advantage can be demonstrated in terms of efficiency and performance. Testing the predictions will require gravitational wave generators with high power and wavelength short enough for producing high energy densities. Detectors designed for the specific application must be developed, taking into account that non-linearity effects are expected. The study and development of Gravitational wave propulsion is a very challenging endeavor, involving the most complex theories, sophisticated
Those Elusive Gravitational Waves
ERIC Educational Resources Information Center
MOSAIC, 1976
1976-01-01
The presence of gravitational waves was predicted by Einstein in his theory of General Relativity. Since then, scientists have been attempting to develop a detector sensitive enough to measure these cosmic signals. Once the presence of gravitational waves is confirmed, scientists can directly study star interiors, galaxy cores, or quasars. (MA)
Advanced Gravitational Wave Detectors
NASA Astrophysics Data System (ADS)
Blair, D. G.; Howell, E. J.; Ju, L.; Zhao, C.
2012-02-01
Part I. An Introduction to Gravitational Wave Astronomy and Detectors: 1. Gravitational waves D. G. Blair, L. Ju, C. Zhao and E. J. Howell; 2. Sources of gravitational waves D. G. Blair and E. J. Howell; 3. Gravitational wave detectors D. G. Blair, L. Ju, C. Zhao, H. Miao, E. J. Howell, and P. Barriga; 4. Gravitational wave data analysis B. S. Sathyaprakash and B. F. Schutz; 5. Network analysis L. Wen and B. F. Schutz; Part II. Current Laser Interferometer Detectors: Three Case Studies: 6. The Laser Interferometer Gravitational-Wave Observatory P. Fritschel; 7. The VIRGO detector S. Braccini; 8. GEO 600 H. Lück and H. Grote; Part III. Technology for Advanced Gravitational Wave Detectors: 9. Lasers for high optical power interferometers B. Willke and M. Frede; 10. Thermal noise, suspensions and test masses L. Ju, G. Harry and B. Lee; 11. Vibration isolation: Part 1. Seismic isolation for advanced LIGO B. Lantz; Part 2. Passive isolation J-C. Dumas; 12. Interferometer sensing and control P. Barriga; 13. Stabilizing interferometers against high optical power effects C. Zhao, L. Ju, S. Gras and D. G. Blair; Part IV. Technology for Third Generation Gravitational Wave Detectors: 14. Cryogenic interferometers J. Degallaix; 15. Quantum theory of laser-interferometer GW detectors H. Miao and Y. Chen; 16. ET. A third generation observatory M. Punturo and H. Lück; Index.
Topics in gravitational-wave science: Macroscopic quantum mechanics and black hole physics
NASA Astrophysics Data System (ADS)
Yang, Huan
The theories of relativity and quantum mechanics, the two most important physics discoveries of the 20th century, not only revolutionized our understanding of the nature of space-time and the way matter exists and interacts, but also became the building blocks of what we currently know as modern physics. My thesis studies both subjects in great depths --- this intersection takes place in gravitational-wave physics. The first part of this thesis (Chapter 2) concerns how to minimize the adverse effect of thermal fluctuations on the sensitivity of advanced gravitational detectors, thereby making them closer to being quantum-limited. My colleagues and I present a detailed analysis of coating thermal noise in advanced gravitational-wave detectors, which is the dominant noise source of Advanced LIGO in the middle of the detection frequency band. We identified the two elastic loss angles, clarified the different components of the coating Brownian noise, and obtained their cross spectral densities. The second part of this thesis (Chapters 3 -- 7) concerns formulating experimental concepts and analyzing experimental results that demonstrate the quantum mechanical behavior of macroscopic objects --- as well as developing theoretical tools for analyzing quantum measurement processes. In Chapter 3, we study the open quantum dynamics of optomechanical experiments in which a single photon strongly influences the quantum state of a mechanical object. We also explain how to engineer the mechanical oscillator's quantum state by modifying the single photon's wave function. The most promising gravitational waves for direct detection are those emitted from highly energetic astrophysical processes, sometimes involving black holes --- a type of object predicted by general relativity whose properties depend highly on the strong-field regime of the theory. Although black holes have been inferred to exist at centers of galaxies and in certain so-called X-ray binary objects, detecting
Gravitational Waves from Neutron Stars: A Review
NASA Astrophysics Data System (ADS)
Lasky, Paul D.
2015-09-01
Neutron stars are excellent emitters of gravitational waves. Squeezing matter beyond nuclear densities invites exotic physical processes, many of which violently transfer large amounts of mass at relativistic velocities, disrupting spacetime and generating copious quantities of gravitational radiation. I review mechanisms for generating gravitational waves with neutron stars. This includes gravitational waves from radio and millisecond pulsars, magnetars, accreting systems, and newly born neutron stars, with mechanisms including magnetic and thermoelastic deformations, various stellar oscillation modes, and core superfluid turbulence. I also focus on what physics can be learnt from a gravitational wave detection, and where additional research is required to fully understand the dominant physical processes at play.
Progress in gravitational wave detection
NASA Astrophysics Data System (ADS)
Cheng, Jing-Quan; Yang, De-Hua
2005-09-01
General theory of Einstein's relativity predicts the existence of gravitational wave when mass is accelerated. However, no material has direct effect when the gravitational wave passes. Therefore, gravitational wave can only be detected indirectly. The effort in gravitational wave detection was started in the 60s of last century by using a huge cylinder of aluminum. This paper introduced all the relevant projects in the gravitational wave detection. These projects include Weber's bar, Laser interferometer Gravitational wave Detector (LGD), Laser Interferometer Gravitational wave Observatory (LIGO), GEO600, VIRGO, TAMA300, Advanced LIGO, Large scale Cryogenic Gravitational wave Telescope (LCGO), and Laser Interferometer Space Antenna (LISA).
Gravitational Waves from Neutron Stars
NASA Astrophysics Data System (ADS)
Kokkotas, Konstantinos
2016-03-01
Neutron stars are the densest objects in the present Universe, attaining physical conditions of matter that cannot be replicated on Earth. These unique and irreproducible laboratories allow us to study physics in some of its most extreme regimes. More importantly, however, neutron stars allow us to formulate a number of fundamental questions that explore, in an intricate manner, the boundaries of our understanding of physics and of the Universe. The multifaceted nature of neutron stars involves a delicate interplay among astrophysics, gravitational physics, and nuclear physics. The research in the physics and astrophysics of neutron stars is expected to flourish and thrive in the next decade. The imminent direct detection of gravitational waves will turn gravitational physics into an observational science, and will provide us with a unique opportunity to make major breakthroughs in gravitational physics, in particle and high-energy astrophysics. These waves, which represent a basic prediction of Einstein's theory of general relativity but have yet to be detected directly, are produced in copious amounts, for instance, by tight binary neutron star and black hole systems, supernovae explosions, non-axisymmetric or unstable spinning neutron stars. The focus of the talk will be on the neutron star instabilities induced by rotation and the magnetic field. The conditions for the onset of these instabilities and their efficiency in gravitational waves will be presented. Finally, the dependence of the results and their impact on astrophysics and especially nuclear physics will be discussed.
NASA Astrophysics Data System (ADS)
Littenberg, Tyson; LIGO Scientific Collaboration
2016-03-01
The BayesWave burst detection and characterization algorithm was used during the first Advanced LIGO observing run as a follow-up analysis to candidate transient gravitational wave events. Among the BayesWave data products are robust reconstructed waveforms and probability density functions for metrics such as duration, bandwidth, etc. used to characterize the waveforms. We will demonstrate how the waveform metrics can be used to infer the astrophysical nature of a gravitational wave source, and present the status of BayesWave studies from the first advanced LIGO observing run.
INFERRING PHYSICAL PARAMETERS OF COMPACT STARS FROM THEIR f-MODE GRAVITATIONAL WAVE SIGNALS
Lau, H. K.; Leung, P. T.; Lin, L. M. E-mail: ptleung@phy.cuhk.edu.h
2010-05-10
We propose here a robust scheme to infer the physical parameters of compact stars from their f-mode gravitational wave signals. We first show that the frequency and the damping rate of f-mode oscillation of compact stars can be expressed in terms of universal functions of stellar mass and moment of inertia. By employing the universality in the f-mode one can then infer accurate values of the mass, the moment of inertia, and the radius of a compact star. In addition, we demonstrate that our new scheme works well for both realistic neutron stars and quark stars, and hence provides a unifying way to infer the physical parameters of compact stars.
NASA Astrophysics Data System (ADS)
seyithocuk; jjeherrera; eltodesukane; GrahamRounce; rloldershaw; Beaker, Dr; Sandhu, G. S.; Ophiuchi
2016-03-01
In reply to the news article on the LIGO collaboration's groundbreaking detection of gravitational waves, first predicted by Einstein 100 years ago, from two black holes colliding (pp5, 6-7 and http://ow.ly/Ylsyt).
Observation of Gravitational Waves
NASA Astrophysics Data System (ADS)
Gonzalez, Gabriela
2016-06-01
On September 14 2015, the two LIGO gravitational wave detectors in Hanford, Washington and Livingston, Louisiana registered a nearly simultaneous signal with time-frequency properties consistent with gravitational-wave emission by the merger of two massive compact objects. Further analysis of the signals by the LIGO Scientific Collaboration and Virgo Collaboration revealed that the gravitational waves detected by LIGO came from the merger of a binary black hole (BBH) system approximately 420 Mpc distant (z=0.09) with constituent masses of 36 and 29 M_sun. I will describe the details of the observation, the status of ground-based interferometric detectors, and prospects for future observations in the new era of gravitational wave astronomy.
Gravitational-Wave Physics and Astronomy Using Ground-Based Interferometers
NASA Astrophysics Data System (ADS)
Reitze, David H.; Shoemaker, David H.
2015-01-01
The past decade has witnessed the successful operation of the first generation of large scale ground-based gravitational-wave interferometers -- LIGO, Virgo, and GEO600 -- each demonstrating remarkably sensitive, robust performance over a series of observing runs beginning in 2002 and continuing through 2011. Although gravitational waves have not yet been directly detected, searches by these detectors have established noteworthy limits on the possible emission of gravitational waves from astrophysical sources. Second generation instruments currently under construction such as Advanced LIGO, Advanced Virgo, and KAGRA will begin observing in the second half of this decade with sensitivities that are predicted to lead to direct detections of binary neutron star mergers and possibly other sources of gravitational waves.
Gravitational lens time delays and gravitational waves
Frieman, J.A. Department of Astronomy Astrophysics, University of Chicago, Chicago, Illinois 60637 ); Harari, D.D.; Surpi, G.C. )
1994-10-15
Using Fermat's principle, we analyze the effects of very long wavelength gravitational waves upon the images of a gravitationally lensed quasar. We show that the lens equation in the presence of gravity waves is equivalent to that of a lens with a different alignment between source, deflector, and observer in the absence of gravity waves. Contrary to a recent claim, we conclude that measurements of time delays in gravitational lenses cannot serve as a method to detect or constrain a stochastic background of gravitational waves of cosmological wavelengths, because the wave-induced time delay is observationally indistinguishable from an intrinsic time delay due to the lens geometry.
NASA Astrophysics Data System (ADS)
Finn, Lee Samuel
2012-03-01
If two black holes collide in a vacuum, can they be observed? Until recently, the answer would have to be "no." After all, how would we observe them? Black holes are "naked" mass: pure mass, simple mass, mass devoid of any matter whose interactions might lead to the emission of photons or neutrinos, or any electromagnetic fields that might accelerate cosmic rays or leave some other signature that we could observe in our most sensitive astronomical instruments. Still, black holes do have mass. As such, they interact—like all mass—gravitationally. And the influence of gravity, like all influences, propagates no faster than that universal speed we first came to know as the speed of light. The effort to detect that propagating influence, which we term as gravitational radiation or gravitational waves, was initiated just over 50 years ago with the pioneering work of Joe Weber [1] and has been the object of increasingly intense experimental effort ever since. Have we, as yet, detected gravitational waves? The answer is still "no." Nevertheless, the accumulation of the experimental efforts begun fifty years ago has brought us to the point where we can confidently say that gravitational waves will soon be detected and, with that first detection, the era of gravitational wave astronomy—the observational use of gravitational waves, emitted by heavenly bodies—will begin. Data analysis for gravitational wave astronomy is, today, in its infancy and its practitioners have much to learn from allied fields, including machine learning. Machine learning tools and techniques have not yet been applied in any extensive or substantial way to the study or analysis of gravitational wave data. It is fair to say that this owes principally to the fields relative youth and not to any intrinsic unsuitability of machine learning tools to the analysis problems the field faces. Indeed, the nature of many of the analysis problems faced by the field today cry-out for the application of
Gravitational waves: A probe to the physics in the early universe
NASA Astrophysics Data System (ADS)
Huang, Qing-Guo
2015-10-01
Gravitational waves can escape from the big bang and can be taken as a probe to the physics, in particular the inflation, in the early universe. Planck scale is a fundamental scale for quantum theory of gravity. Requiring the excursion distance of inflaton in the field space during inflation yields an upper bound on the tensor-to-scalar ratio. For example, r < 7 × 10-4 for ns = 0.9645. In the typical inflationary scenario, we predict 1 - 2/N < ns < 1 and - 2/N2 < α s < 0 which are consistent with Planck data released in 2015 quite well. Subtracting the contribution of thermal dust measured by Planck, BICEP2 data implies r ≲ 0.08 which is the tightest bound on the tensor-to-scalar ratio from current experiments.
NASA Astrophysics Data System (ADS)
Mottola, Emil
2016-03-01
General Relativity receives quantum corrections relevant at macroscopic distance scales and near event horizons. These arise from the conformal scalar degree of freedom in the extended effective field theory (EFT) of gravity generated by the trace anomaly of massless quantum fields in curved space. Linearized around flat space this quantum scalar degree of freedom combines with the conformal part of the metric and predicts the existence of scalar spin-0 ``breather'' propagating gravitational waves in addition to the transverse tensor spin-2 waves of classical General Relativity. Estimates of the expected strength of scalar gravitational radiation from compact astrophysical sources are given.
Astronomy's New Messengers: A traveling exhibit on gravitational-wave physics
NASA Astrophysics Data System (ADS)
Cavaglià, Marco; Hendry, Martin; Márka, Szabolcs; Reitze, David H.; Riles, Keith
2010-01-01
The Laser Interferometer Gravitational-wave Observatory exhibit Astronomy's New Messengers: Listening to the Universe with Gravitational Waves is traveling to colleges, universities, museums and other public institutions throughout the United States. Astronomy's New Messengers primarily communicates with an adolescent and young adult audience, potentially inspiring them into the field of science. Acknowledging that this audience is traditionally a difficult one to attract, the exhibit publicly announces itself in a charismatic fashion to reach its principal goals of broadening the community of people interested in science and encouraging interest in science among young people.
Sources of gravitational waves
NASA Technical Reports Server (NTRS)
Schutz, Bernard F.
1989-01-01
Sources of low frequency gravitational radiation are reviewed from an astrophysical point of view. Cosmological sources include the formation of massive black holes in galactic nuclei, the capture by such holes of neutron stars, the coalescence of orbiting pairs of giant black holes, and various means of producing a stochastic background of gravitational waves in the early universe. Sources local to our Galaxy include various kinds of close binaries and coalescing binaries. Gravitational wave astronomy can provide information that no other form of observing can supply; in particular, the positive identification of a cosmological background originating in the early universe would be an event as significant as was the detection of the cosmic microwave background.
Gravitational Waves: The Evidence Mounts
ERIC Educational Resources Information Center
Wick, Gerald L.
1970-01-01
Reviews the work of Weber and his colleagues in their attempts at detecting extraterrestial gravitational waves. Coincidence events recorded by special detectors provide the evidence for the existence of gravitational waves. Bibliography. (LC)
The gravitational wave experiment
NASA Technical Reports Server (NTRS)
Bertotti, B.; Ambrosini, R.; Asmar, S. W.; Brenkle, J. P.; Comoretto, G.; Giampieri, G.; Less, L.; Messeri, A.; Wahlquist, H. D.
1992-01-01
Since the optimum size of a gravitational wave detector is the wave length, interplanetary dimensions are needed for the mHz band of interest. Doppler tracking of Ulysses will provide the most sensitive attempt to date at the detection of gravitational waves in the low frequency band. The driving noise source is the fluctuations in the refractive index of interplanetary plasma. This dictates the timing of the experiment to be near solar opposition and sets the target accuracy for the fractional frequency change at 3.0 x 10 exp -14 for integration times of the order of 1000 sec. The instrumentation utilized by the experiment is distributed between the radio systems on the spacecraft and the seven participating ground stations of the Deep Space Network and Medicina. Preliminary analysis is available of the measurements taken during the Ulysses first opposition test.
Nonlinear evolution of cylindrical gravitational waves: Numerical method and physical aspects
NASA Astrophysics Data System (ADS)
Celestino, Juliana; de Oliveira, H. P.; Rodrigues, E. L.
2016-05-01
General cylindrical waves are the simplest axisymmetrical gravitational waves that contain both + and × modes of polarization. In this paper, we have studied the evolution of general cylindrical gravitational waves in the realm of the characteristic scheme with a numerical code based on the Galerkin-Collocation method. The investigation consists of the numerical realization of concepts such as Bondi mass and the news functions adapted to cylindrical symmetry. The Bondi mass decays due to the presence of the news functions associated with both polarization modes. We have interpreted each polarization mode as channels from which mass is extracted. Under this perspective, we have presented the enhancement effect of the polarization mode + due to the nonlinear interaction with the mode ×. After discussing the role of matter in cylindrical symmetry, we have extended the numerical code to include electromagnetic fields.
Primordial gravitational waves and cosmology.
Krauss, Lawrence M; Dodelson, Scott; Meyer, Stephan
2010-05-21
The observation of primordial gravitational waves could provide a new and unique window on the earliest moments in the history of the universe and on possible new physics at energies many orders of magnitude beyond those accessible at particle accelerators. Such waves might be detectable soon, in current or planned satellite experiments that will probe for characteristic imprints in the polarization of the cosmic microwave background, or later with direct space-based interferometers. A positive detection could provide definitive evidence for inflation in the early universe and would constrain new physics from the grand unification scale to the Planck scale. PMID:20489015
NASA Astrophysics Data System (ADS)
Finn, L. S.
Astronomers rely on a multiplicity of observational perspectives in order to infer the nature of the Universe. Progress in astronomy has historically been associated with new or improved observational perspectives. Gravitational wave detectors now under construction will provide us with a perspective on the Universe fundamentally different from any we have come to know. With this new perspective comes the hope of new insights and understanding, not just of exotic astrophysical processes, but of "bread-and-butter" astrophysics: e.g., stars and stellar evolution, galaxy formation and evolution, neutron star structure, and cosmology. In this report the author discusses briefly a small subset of the areas of conventional, "bread-and-butter" astrophysics where we can reasonably hope that gravitational wave observations will provide us with valuable new insights and understandings.
From Measure Zero to Measure Hero: Periodic Kerr Orbits and Gravitational Wave Physics
NASA Astrophysics Data System (ADS)
Perez-Giz, Gabriel
2011-12-01
A direct observational detection of gravitational waves -- perhaps the most fundamental prediction of a theory of curved spacetime -- looms close at hand. Stellar mass compact objects spiraling into supermassive black holes have received particular attention as sources of gravitational waves detectable by space-based gravitational wave observatories. A well-established approach models such an extreme mass ratio inspirals (EMRI) as an adiabatic progression through a series of Kerr geodesics. Thus, the direct detection of gravitational radiation from EMRIs and the extraction of astrophysical information from those waveforms require a thorough knowledge of the underlying geodesic dynamics. This dissertation adopts a dynamical systems approach to the study of Kerr orbits, beginning with equatorial orbits. We deduce a topological taxonomy of orbits that hinges on a correspondence between periodic orbits and rational numbers. The taxonomy defines the entire dynamics, including aperiodic motion, since every orbit is in or near the periodic set. A remarkable implication of this periodic orbit taxonomy is that the simple precessing ellipse familiar from planetary orbits is not allowed in the strong-field regime. Instead, eccentric orbits trace out precessions of multi-leaf clovers in the final stages of inspiral. Furthermore, for any black hole, there is some orbital angular momentum value in the strong-field regime below which zoom-whirl behavior becomes unavoidable. We then generalize the taxonomy to help identify nonequatorial orbits whose radial and polar frequencies are rationally related, or in resonance. The thesis culminates by describing how those resonant orbits can be leveraged for an order of magnitude or more reduction in the computational cost of adiabatic order EMRI trajectories, which are so prohibitively expensive that no such relativistically correct inspirals have been generated to date.
Gravitational wave science from space
NASA Astrophysics Data System (ADS)
Gair, Jonathan R.
2016-05-01
The rich millihertz gravitational wave band can only be accessed with a space- based detector. The technology for such a detector will be demonstrated by the LISA Pathfinder satellite that is due to launch this year and ESA has selected gravitational wave detection from space as the science theme to be addressed by the L3 large mission to be launched around 2034. In this article we will discuss the sources that such an instrument will observe, and how the numbers of events and precision of parameter determination are affected by modifications to the, as yet not finalised, mission design. We will also describe some of the exciting scientific applications of these observations, to astrophysics, fundamental physics and cosmology.
Quantum Emulation of Gravitational Waves
Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel
2015-01-01
Gravitational waves, as predicted by Einstein’s general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials. PMID:26169801
Quantum Emulation of Gravitational Waves.
Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel
2015-01-01
Gravitational waves, as predicted by Einstein's general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials. PMID:26169801
Gravitational wave emission from oscillating millisecond pulsars
NASA Astrophysics Data System (ADS)
Alford, Mark G.; Schwenzer, Kai
2015-02-01
Neutron stars undergoing r-mode oscillation emit gravitational radiation that might be detected on the Earth. For known millisecond pulsars the observed spin-down rate imposes an upper limit on the possible gravitational wave signal of these sources. Taking into account the physics of r-mode evolution, we show that only sources spinning at frequencies above a few hundred Hertz can be unstable to r-modes, and we derive a more stringent universal r-mode spin-down limit on their gravitational wave signal. We find that this refined bound limits the gravitational wave strain from millisecond pulsars to values below the detection sensitivity of next generation detectors. Young sources are therefore a more promising option for the detection of gravitational waves emitted by r-modes and to probe the interior composition of compact stars in the near future.
On the Unreasonable Effectiveness of post-Newtonian Theory in Gravitational-Wave Physics
Clifford M. Will
2010-01-08
The first indirect detection of gravitational waves involved a binary system of neutron stars. In the future, the first direct detection may also involve binary systems -- inspiralling and merging binary neutron stars or black holes. This means that it is essential to understand in full detail the two-body system in general relativity, a notoriously difficult problem with a long history. Post-Newtonian approximation methods are thought to work only under slow motion and weak field conditions, while numerical solutions of Einstein's equations are thought to be limited to the final merger phase. Recent results have shown that post-Newtonian approximations seem to remain unreasonably valid well into the relativistic regime, while advances in numerical relativity now permit solutions for numerous orbits before merger. It is now possible to envision linking post-Newtonian theory and numerical relativity to obtain a complete ``solution'' of the general relativistic two-body problem. These solutions will play a central role in detecting and understanding gravitational wave signals received by interferometric observatories on Earth and in space.
NASA Astrophysics Data System (ADS)
Cokelaer, T.
2007-11-01
Matched filtering is used to search for gravitational waves emitted by inspiralling compact binaries in data from the ground-based interferometers. One of the key aspects of the detection process is the design of a template bank that covers the astrophysically pertinent parameter space. In an earlier paper, we described a template bank that is based on a square lattice. Although robust, we showed that the square placement is overefficient, with the implication that it is computationally more demanding than required. In this paper, we present a template bank based on an hexagonal lattice, which size is reduced by 40% with respect to the proposed square placement. We describe the practical aspects of the hexagonal template bank implementation, its size, and computational cost. We have also performed exhaustive simulations to characterize its efficiency and safeness. We show that the bank is adequate to search for a wide variety of binary systems (primordial black holes, neutron stars, and stellar-mass black holes) and in data from both current detectors (initial LIGO, Virgo and GEO600) as well as future detectors (advanced LIGO and EGO). Remarkably, although our template bank placement uses a metric arising from a particular template family, namely, stationary phase approximation, we show that it can be used successfully with other template families (e.g., Padé resummation and effective one-body approximation). This quality of being effective for different template families makes the proposed bank suitable for a search that would use several of them in parallel (e.g., in a binary black hole search). The hexagonal template bank described in this paper is currently used to search for nonspinning inspiralling compact binaries in data from the Laser Interferometer Gravitational-Wave Observatory (LIGO).
Cokelaer, T.
2007-11-15
Matched filtering is used to search for gravitational waves emitted by inspiralling compact binaries in data from the ground-based interferometers. One of the key aspects of the detection process is the design of a template bank that covers the astrophysically pertinent parameter space. In an earlier paper, we described a template bank that is based on a square lattice. Although robust, we showed that the square placement is overefficient, with the implication that it is computationally more demanding than required. In this paper, we present a template bank based on an hexagonal lattice, which size is reduced by 40% with respect to the proposed square placement. We describe the practical aspects of the hexagonal template bank implementation, its size, and computational cost. We have also performed exhaustive simulations to characterize its efficiency and safeness. We show that the bank is adequate to search for a wide variety of binary systems (primordial black holes, neutron stars, and stellar-mass black holes) and in data from both current detectors (initial LIGO, Virgo and GEO600) as well as future detectors (advanced LIGO and EGO). Remarkably, although our template bank placement uses a metric arising from a particular template family, namely, stationary phase approximation, we show that it can be used successfully with other template families (e.g., Pade resummation and effective one-body approximation). This quality of being effective for different template families makes the proposed bank suitable for a search that would use several of them in parallel (e.g., in a binary black hole search). The hexagonal template bank described in this paper is currently used to search for nonspinning inspiralling compact binaries in data from the Laser Interferometer Gravitational-Wave Observatory (LIGO)
NASA Astrophysics Data System (ADS)
Belczynski, Krzysztof; Kalogera, Vassiliki; Bulik, Tomasz
2002-06-01
A new generation of ground-based interferometric detectors for gravitational waves is currently under construction or has entered the commissioning phase (Laser Interferometer Gravitational-wave Observatory [LIGO], VIRGO, GEO600, TAMA300). The purpose of these detectors is to observe gravitational waves from astrophysical sources and help improve our understanding of the source origin and physical properties. In this paper we study the most promising candidate sources for these detectors: inspiraling double compact objects. We use population synthesis methods to calculate the properties and coalescence rates of compact object binaries: double neutron stars, black hole-neutron star systems, and double black holes. We also examine the formation channels available to double compact object binaries. We explicitly account for the evolution of low-mass helium stars and investigate the possibility of common-envelope evolution involving helium stars as well as two evolved stars. As a result we identify a significant number of new formation channels for double neutron stars, in particular, leading to populations with very distinct properties. We discuss the theoretical and observational implications of such populations, but we also note the need for hydrodynamical calculations to settle the question of whether such common-envelope evolution is possible. We also present and discuss the physical properties of compact object binaries and identify a number of robust, qualitative features as well as their origin. Using the calculated coalescence rates we compare our results to earlier studies and derive expected detection rates for LIGO. We find that our most optimistic estimate for the first LIGO detectors reach a couple of events per year and our most pessimistic estimate for advanced LIGO detectors exceed ~=10 events per year.
Building a Galactic Scale Gravitational Wave Observatory
NASA Astrophysics Data System (ADS)
McLaughlin, Maura
2016-03-01
Pulsars are rapidly rotating neutron stars with phenomenal rotational stability that can be used as celestial clocks in a variety of fundamental physics experiences. One of these experiments involves using a pulsar timing array of precisely timed millisecond pulsars to detect perturbations due to gravitational waves. The low frequency gravitational waves detectable through pulsar timing will most likely result from an ensemble of supermassive black hole binaries. I will introduce the efforts of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), a collaboration that monitors over 50 millisecond pulsars with the Green Bank Telescope and the Arecibo Observatory, with a focus on our observation and data analysis methods. I will also describe how NANOGrav has joined international partners through the International Pulsar Timing Array to form a low-frequency gravitational wave detector of unprecedented sensitivity.
NASA Astrophysics Data System (ADS)
Taylor, Stephen; Sampson, Laura; Simon, Joseph
2016-03-01
There has recently been significant interest in how the galactic environments of supermassive black-hole binaries influences the stochastic gravitational-wave background signal from a population of these systems, and in how the resulting detection prospects for pulsar-timing arrays are effected. Tackling these problems requires us to have robust and computationally-efficient models for the strain spectrum as a function of different environment influences or the binary orbital eccentricity. In this talk we describe a new method of constructing these models from a small number of synthesized black-hole binary populations which have varying input physics. We use these populations to train an interpolant via Gaussian-process regression, allowing us to carry real physics into our subsequent pulsar-timing array inferences, and to also correctly propagate forward uncertainties from our interpolation.
Quantum Opportunities in Gravitational Wave Detectors
Mavalvala, Negris
2012-03-14
Direct observation of gravitational waves should open a new window into the Universe. Gravitational wave detectors are the most sensitive position meters ever constructed. The quantum limit in gravitational wave detectors opens up a whole new field of study. Quantum opportunities in gravitational wave detectors include applications of quantum optics techniques and new tools for quantum measurement on truly macroscopic (human) scales.
Gravitational-wave sensitivity curves
NASA Astrophysics Data System (ADS)
Moore, C. J.; Cole, R. H.; Berry, C. P. L.
2015-01-01
There are several common conventions in use by the gravitational-wave community to describe the amplitude of sources and the sensitivity of detectors. These are frequently confused. We outline the merits of and differences between the various quantities used for parameterizing noise curves and characterizing gravitational-wave amplitudes. We conclude by producing plots that consistently compare different detectors. Similar figures can be generated on-line for general use at http://rhcole.com/apps/GWplotter.
Geometrical versus wave optics under gravitational waves
NASA Astrophysics Data System (ADS)
Angélil, Raymond; Saha, Prasenjit
2015-06-01
We present some new derivations of the effect of a plane gravitational wave on a light ray. A simple interpretation of the results is that a gravitational wave causes a phase modulation of electromagnetic waves. We arrive at this picture from two contrasting directions, namely, null geodesics and Maxwell's equations, or geometric and wave optics. Under geometric optics, we express the geodesic equations in Hamiltonian form and solve perturbatively for the effect of gravitational waves. We find that the well-known time-delay formula for light generalizes trivially to massive particles. We also recover, by way of a Hamilton-Jacobi equation, the phase modulation obtained under wave optics. Turning then to wave optics—rather than solving Maxwell's equations directly for the fields, as in most previous approaches—we derive a perturbed wave equation (perturbed by the gravitational wave) for the electromagnetic four-potential. From this wave equation it follows that the four-potential and the electric and magnetic fields all experience the same phase modulation. Applying such a phase modulation to a superposition of plane waves corresponding to a Gaussian wave packet leads to time delays.
Multibaseline gravitational wave radiometry
Talukder, Dipongkar; Bose, Sukanta; Mitra, Sanjit
2011-03-15
We present a statistic for the detection of stochastic gravitational wave backgrounds (SGWBs) using radiometry with a network of multiple baselines. We also quantitatively compare the sensitivities of existing baselines and their network to SGWBs. We assess how the measurement accuracy of signal parameters, e.g., the sky position of a localized source, can improve when using a network of baselines, as compared to any of the single participating baselines. The search statistic itself is derived from the likelihood ratio of the cross correlation of the data across all possible baselines in a detector network and is optimal in Gaussian noise. Specifically, it is the likelihood ratio maximized over the strength of the SGWB and is called the maximized-likelihood ratio (MLR). One of the main advantages of using the MLR over past search strategies for inferring the presence or absence of a signal is that the former does not require the deconvolution of the cross correlation statistic. Therefore, it does not suffer from errors inherent to the deconvolution procedure and is especially useful for detecting weak sources. In the limit of a single baseline, it reduces to the detection statistic studied by Ballmer [Classical Quantum Gravity 23, S179 (2006).] and Mitra et al.[Phys. Rev. D 77, 042002 (2008).]. Unlike past studies, here the MLR statistic enables us to compare quantitatively the performances of a variety of baselines searching for a SGWB signal in (simulated) data. Although we use simulated noise and SGWB signals for making these comparisons, our method can be straightforwardly applied on real data.
Orientational atom interferometers sensitive to gravitational waves
Lorek, Dennis; Laemmerzahl, Claus; Wicht, Andreas
2010-02-15
We present an atom interferometer that differs from common atom interferometers as it is not based on the spatial splitting of electronic wave functions, but on orienting atoms in space. As an example we present how an orientational atom interferometer based on highly charged hydrogen-like atoms is affected by gravitational waves. We show that a monochromatic gravitational wave will cause a frequency shift that scales with the binding energy of the system rather than with its physical dimension. For a gravitational wave amplitude of h=10{sup -23} the frequency shift is of the order of 110 {mu}Hz for an atom interferometer based on a 91-fold charged uranium ion. A frequency difference of this size can be resolved by current atom interferometers in 1 s.
LISA in the gravitational wave decade
NASA Astrophysics Data System (ADS)
Conklin, John; Cornish, Neil
2015-04-01
With the expected direct detection of gravitational waves in the second half of this decade by Advanced LIGO and pulsar timing arrays, and with the launch of LISA Pathfinder in the summer of this year, this can arguably be called the decade of gravitational waves. Low frequency gravitational waves in the mHz range, which can only be observed from space, provide the richest science and complement high frequency observatories on the ground. A space-based observatory will improve our understanding of the formation and growth of massive black holes, create a census of compact binary systems in the Milky Way, test general relativity in extreme conditions, and enable searches for new physics. LISA, by far the most mature concept for detecting gravitational waves from space, has consistently ranked among the nation's top priority large science missions. In 2013, ESA selected the science theme ``The Gravitational Universe'' for its third large mission, L3, under the Cosmic Visions Program, with a planned launch date of 2034. Recently, NASA has decided to join with ESA on the L3 mission as a junior partner. Both agencies formed a committee to advise them on the scientific and technological approaches for a space based gravitational wave observatory. The leading mission design, Evolved LISA or eLISA, is a slightly de-scoped version of the earlier LISA design. This talk will describe activities of the Gravitational Wave Science Interest Group (GWSIG) under the Physics of the Cosmos Program Analysis Group (PhysPAG), focusing on LISA technology development in both the U.S. and Europe, including the LISA Pathfinder mission.
Testing local Lorentz invariance with gravitational waves
NASA Astrophysics Data System (ADS)
Kostelecký, V. Alan; Mewes, Matthew
2016-06-01
The effects of local Lorentz violation on dispersion and birefringence of gravitational waves are investigated. The covariant dispersion relation for gravitational waves involving gauge-invariant Lorentz-violating operators of arbitrary mass dimension is constructed. The chirp signal from the gravitational-wave event GW150914 is used to place numerous first constraints on gravitational Lorentz violation.
Gravitational Physics Research
NASA Technical Reports Server (NTRS)
Wu, S. T.
2000-01-01
Gravitational physics research at ISPAE is connected with NASA's Relativity Mission (Gravity Probe B (GP-B)) which will perform a test of Einstein's General Relativity Theory. GP-B will measure the geodetic and motional effect predicted by General Relativity Theory with extremely stable and sensitive gyroscopes in an earth orbiting satellite. Both effects cause a very small precession of the gyroscope spin axis. The goal of the GP-B experiment is the measurement of the gyroscope precession with very high precision. GP-B is being developed by a team at Stanford University and is scheduled for launch in the year 2001. The related UAH research is a collaboration with Stanford University and MSFC. This research is focussed primarily on the error analysis and data reduction methods of the experiment but includes other topics concerned with experiment systems and their performance affecting the science measurements. The hydrogen maser is the most accurate and stable clock available. It will be used in future gravitational physics missions to measure relativistic effects such as the second order Doppler effect. The HMC experiment, currently under development at the Smithsonian Astrophysical Observatory (SAO), will test the performance and capability of the hydrogen maser clock for gravitational physics measurements. UAH in collaboration with the SAO science team will study methods to evaluate the behavior and performance of the HMC. The GP-B data analysis developed by the Stanford group involves complicated mathematical operations. This situation led to the idea to investigate alternate and possibly simpler mathematical procedures to extract the GP-B measurements form the data stream. Comparison of different methods would increase the confidence in the selected scheme.
Conformal Gravity and Gravitational Waves
NASA Astrophysics Data System (ADS)
Fabbri, Luca; Paranjape, M. B.
We consider monochromatic, plane gravitational waves in a conformally invariant theory of general relativity. We show that the simple, standard ansatz for the metric, usually that which is taken for the linearized theory of these waves, is reducible to the metric of Minkowski spacetime via a sequence of conformal and coordinate transformations. This implies that we have in fact, exact plane wave solutions. However they are simply coordinate/conformal artifacts. As a consequence, they carry no energy.
CCSNMultivar: Core-Collapse Supernova Gravitational Waves
NASA Astrophysics Data System (ADS)
Engels, Bill; Gossan, Sarah
2016-04-01
CCSNMultivar aids the analysis of core-collapse supernova gravitational waves. It includes multivariate regression of Fourier transformed or time domain waveforms, hypothesis testing for measuring the influence of physical parameters, and the Abdikamalov et. al. catalog for example use. CCSNMultivar can optionally incorporate additional uncertainty due to detector noise and approximate waveforms from anywhere within the parameter space.
GRAVITATIONAL WAVES FROM STELLAR COLLAPSE
C. L. FRYER
2001-01-01
Stellar core-collapse plays an important role in nearly all facets of astronomy: cosmology (as standard candles), formation of compact objects, nucleosynthesis and energy deposition in galaxies. In addition, they release energy in powerful explosions of light over a range of energies, neutrinos, and the subject of this meeting, gravitational waves. Because of this broad range of importance, astronomers have discovered a number of constraints which can be used to help them understand the importance of stellar core-collapse as gravitational wave sources.
The Detection of Gravitational Waves
NASA Astrophysics Data System (ADS)
Braccini, Stefano; Fidecaro, Francesco
The detection of gravitational waves is challenging researchers since half a century. The relative precision required, 10^{-21}, is difficult to imagine, this is 10^{-5} the diameter of a proton over several kilometres, using masses of tens of kilograms, or picometres over millions of kilometres. A theoretical description of gravitational radiation and its effects on matter, all consequence of the general theory of relativity, is given. Then the astrophysical phenomena that are candidates of gravitational wave emission are discussed, considering also amplitudes and rates. The binary neutron star system PSR1913+16, which provided the first evidence for energy loss by gravitational radiation in 1975, is briefly discussed. Then comes a description of the experimental developments, starting with ground-based interferometers, their working principles and their most important sources of noise. The earth-wide network that is being built describes how these instruments will be used in the observation era. Several other detection techniques, such as space interferometry, pulsar timing arrays and resonant detectors, covering different bands of the gravitational wave frequency spectrum complete these lectures.
Gravitational waves and multimessenger astronomy
NASA Astrophysics Data System (ADS)
Ricci, Fulvio
2016-07-01
It is widely expected that in the coming quinquennium the first gravitational wave signal will be directly detected. The ground-based advanced LIGO and Virgo detectors are being upgraded to a sensitivity level such that we expect to be measure a significant binary merger rate. Gravitational waves events are likely to be accompanied by electromagnetic counterparts and neutrino emission carrying complementary information to those associated to the gravitational signals. If it becomes possible to measure all these forms of radiation in concert, we will end up an impressive increase in the comprehension of the whole phenomenon. In the following we summarize the scientific outcome of the interferometric detectors in the past configuration. Then we focus on some of the potentialities of the advanced detectors once used in the new context of the multimessenger astronomy.
Merging Black Holes and Gravitational Waves
NASA Technical Reports Server (NTRS)
Centrella, Joan
2009-01-01
This talk will focus on simulations of binary black hole mergers and the gravitational wave signals they produce. Applications to gravitational wave detection with LISA, and electronagnetic counterparts, will be highlighted.
Theory and detection of gravitational waves
NASA Astrophysics Data System (ADS)
Pizzella, G.
The role of gravitational waves in general relativity is examined. It is found that the gravitational waves are a particular solution of the Einstein equations. The computation of the energy flux emitted by moving bodies as gravitational waves is very similar to that for electromagnetic waves. A description of gravitational wave sources is presented, taking into account a spinning star, double star systems, the fall into a Schwarzschild black hole, and radiation from gravitational collapse. Questions regarding the interaction of gravitational waves with matter are explored, and the interaction of a gravitational wave with oscillators and an elastic cylinder is considered. Electromechanical transducers are discussed, giving attention to the piezoelectric ceramic, the capacitor, the inductor, the Brownian noise of the bar, the backreaction, the wide band noise, and data analysis. The design of a gravitational wave antenna is also described.
Gravitational waves carrying orbital angular momentum
NASA Astrophysics Data System (ADS)
Bialynicki-Birula, Iwo; Bialynicka-Birula, Zofia
2016-02-01
Spinorial formalism is used to map every electromagnetic wave into the gravitational wave (within the linearized gravity). In this way we can obtain the gravitational counterparts of Bessel, Laguerre-Gauss, and other light beams carrying orbital angular momentum.
Hunting gravitational waves using pulsars
NASA Astrophysics Data System (ADS)
Mayor, Louise
2014-10-01
With the first direct detection of gravitational waves at the top of many physicists' wish list, Louise Mayor describes how radio astronomers are hoping to reveal these ripples in space-time by pointing their telescopes at an array of distant pulsars.
Relic gravitational waves produced after preheating
Khlebnikov, S.; Tkachev, I. |
1997-07-01
We show that gravitational radiation is produced quite efficiently in interactions of classical waves created by resonant decay of a coherently oscillating field. As an important example we consider simple models of chaotic inflation, where we find that today{close_quote}s ratio of energy density in gravitational waves per octave to the critical density of the Universe can be as large as 10{sup {minus}12} at the maximal wavelength of order 10{sup 5} cm. In the pure {lambda}{phi}{sup 4}/4 model with inflaton self-coupling {lambda}=10{sup {minus}13}, the maximal today{close_quote}s wavelength of gravitational waves produced by this mechanism is of order 10{sup 6} cm, close to the upper bound of operational LIGO and TIGA frequencies. The energy density of waves in this model, though, is likely to be well below the sensitivity of LIGO or TIGA at such frequencies. We discuss the possibility that in other models the interaction of classical waves can lead to an even stronger gravitational radiation background. {copyright} {ital 1997} {ital The American Physical Society}
Gravitational Wave Astrophysics: Opening the New Frontier
NASA Technical Reports Server (NTRS)
Centrella, Joan
2011-01-01
The gravitational wave window onto the universe is expected to open in 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This article explores gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum. Keywords: Gravitational wave astrophysics; gravitational radiation; gravitational wave detectors; black holes.
Identifying the inflaton with primordial gravitational waves.
Easson, Damien A; Powell, Brian A
2011-05-13
We explore the ability of experimental physics to uncover the underlying structure of the gravitational Lagrangian describing inflation. While the observable degeneracy of the inflationary parameter space is large, future measurements of observables beyond the adiabatic and tensor two-point functions, such as non-gaussianity or isocurvature modes, might reduce this degeneracy. We show that, even in the absence of such observables, the range of possible inflaton potentials can be reduced with a precision measurement of the tensor spectral index, as might be possible with a direct detection of primordial gravitational waves. PMID:21668140
The Japanese space gravitational wave antenna - DECIGO
NASA Astrophysics Data System (ADS)
Kawamura, S.; Ando, M.; Nakamura, T.; Tsubono, K.; Tanaka, T.; Funaki, I.; Seto, N.; Numata, K.; Sato, S.; Ioka, K.; Kanda, N.; Takashima, T.; Agatsuma, K.; Akutsu, T.; Akutsu, T.; Aoyanagi, Koh-Suke; Arai, K.; Arase, Y.; Araya, A.; Asada, H.; Aso, Y.; Chiba, T.; Ebisuzaki, T.; Enoki, M.; Eriguchi, Y.; Fujimoto, M.-K.; Fujita, R.; Fukushima, M.; Futamase, T.; Ganzu, K.; Harada, T.; Hashimoto, T.; Hayama, K.; Hikida, W.; Himemoto, Y.; Hirabayashi, H.; Hiramatsu, T.; Hong, F.-L.; Horisawa, H.; Hosokawa, M.; Ichiki, K.; Ikegami, T.; Inoue, K. T.; Ishidoshiro, K.; Ishihara, H.; Ishikawa, T.; Ishizaki, H.; Ito, H.; Itoh, Y.; Kamagasako, S.; Kawashima, N.; Kawazoe, F.; Kirihara, H.; Kishimoto, N.; Kiuchi, K.; Kobayashi, S.; Kohri, K.; Koizumi, H.; Kojima, Y.; Kokeyama, K.; Kokuyama, W.; Kotake, K.; Kozai, Y.; Kudoh, H.; Kunimori, H.; Kuninaka, H.; Kuroda, K.; Maeda, K.-i.; Matsuhara, H.; Mino, Y.; Miyakawa, O.; Miyoki, S.; Morimoto, M. Y.; Morioka, T.; Morisawa, T.; Moriwaki, S.; Mukohyama, S.; Musha, M.; Nagano, S.; Naito, I.; Nakagawa, N.; Nakamura, K.; Nakano, H.; Nakao, K.; Nakasuka, S.; Nakayama, Y.; Nishida, E.; Nishiyama, K.; Nishizawa, A.; Niwa, Y.; Ohashi, M.; Ohishi, N.; Ohkawa, M.; Okutomi, A.; Onozato, K.; Oohara, K.; Sago, N.; Saijo, M.; Sakagami, M.; Sakai, S.-i.; Sakata, S.; Sasaki, M.; Sato, T.; Shibata, M.; Shinkai, H.; Somiya, K.; Sotani, H.; Sugiyama, N.; Suwa, Y.; Tagoshi, H.; Takahashi, K.; Takahashi, K.; Takahashi, T.; Takahashi, H.; Takahashi, R.; Takahashi, R.; Takamori, A.; Takano, T.; Taniguchi, K.; Taruya, A.; Tashiro, H.; Tokuda, M.; Tokunari, M.; Toyoshima, M.; Tsujikawa, S.; Tsunesada, Y.; Ueda, K.-i.; Utashima, M.; Yamakawa, H.; Yamamoto, K.; Yamazaki, T.; Yokoyama, J.; Yoo, C.-M.; Yoshida, S.; Yoshino, T.
2008-07-01
DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. The goal of DECIGO is to detect gravitational waves from various kinds of sources mainly between 0.1 Hz and 10 Hz and thus to open a new window of observation for gravitational wave astronomy. DECIGO will consist of three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by a Fabry—Perot Michelson interferometer. We plan to launch DECIGO pathfinder first to demonstrate the technologies required to realize DECIGO and, if possible, to detect gravitational waves from our galaxy or nearby galaxies.
Gravitational Wave Astrophysics: Opening the New Frontier
NASA Technical Reports Server (NTRS)
Centrella, Joan
2011-01-01
The gravitational wave window onto the universe is expected to open in approximately 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This talk will explore gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum.
Gravitational Wave Astrophysics: Opening the New Frontier
NASA Technical Reports Server (NTRS)
Centrella, Joan
2011-01-01
The gravitational wave window onto the universe is expected to open in approx. 5 years, when ground-based detectors make the first detections in the high-frequency regime. Gravitational waves are ripples in spacetime produced by the motions of massive objects such as black holes and neutron stars. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters, through dense, obscured regions across cosmic time. This article explores gravitational waves as cosmic messengers, highlighting key sources, detection methods, and the astrophysical payoffs across the gravitational wave spectrum.
Gravitational waves from perturbed stars
NASA Astrophysics Data System (ADS)
Ferrari, V.
2011-12-01
Non radial oscillations of neutron stars are associated with the emission of gravitational waves. The characteristic frequencies of these oscillations can be computed using the theory of stellar perturbations, and they are shown to carry detailed information on the internal structure of the emitting source. Moreover, they appear to be encoded in various radiative processes, as for instance, in the tail of the giant flares of Soft Gamma Repeaters. Thus, their determination is central to the theory of stellar perturbation. A viable approach to the problem consists in formulating this theory as a problem of resonant scattering of gravitational waves incident on the potential barrier generated by the spacetime curvature. This approach discloses some unexpected correspondences between the theory of stellar perturbations and the theory of quantum mechanics, and allows us to predict new relativistic effects.
Gravitational waves from perturbed stars
NASA Astrophysics Data System (ADS)
Ferrari, V.
2011-03-01
Non radial oscillations of neutron stars are associated with the emission of gravitational waves. The characteristic frequencies of these oscillations can be computed using the theory of stellar perturbations, and they are shown to carry detailed information on the internal structure of the emitting source. Moreover, they appear to be encoded in various radiative processes, as for instance in the tail of the giant flares of Soft Gamma Repeaters. Thus, their determination is central to the theory of stellar perturbation. A viable approach to the problem consists in formulating this theory as a problem of resonant scattering of gravitational waves incident on the potential barrier generated by the spacetime curvature. This approach discloses some unexpected correspondences between the theory of stellar perturbations and the theory of quantum mechanics, and allows us to predict new relativistic effects.
Liu Jinzhong; Han Zhanwen; Zhang Fenghui; Zhang Yu
2010-08-20
Close double white dwarfs (CDWDs) are believed to dominate the Galactic gravitational wave (GW) radiation in the frequency range 10{sup -4} to 0.1 Hz, which will be detected by the Laser Interferometer Space Antenna (LISA) detector. The aim of this detector is to detect GW radiation from astrophysical sources in the universe and to help improve our understanding of the origin of the sources and their physical properties (masses and orbital periods). In this paper, we study the probable candidate sources in the Galaxy for the LISA detector: CDWDs. We use the binary population synthesis approach of CDWDs together with the latest findings of the synthesis models from Han, who proposed three evolutionary channels: (1) stable Roche lobe overflow plus common envelope (RLOF+CE), (2) CE+CE, and (3) exposed core plus CE. As a result, we systematically investigate the detailed physical properties (the distributions of masses, orbital periods, and chirp masses) of the CDWD sources for the LISA detector, examine the importance of the three evolutionary channels for the formation of CDWDs, and carry out Monte Carlo simulations. Our results show that RLOF+CE and CE+CE are the main evolutionary scenarios leading to the formation of CDWDs. For the LISA detectable sources, we also explore and discuss the importance of these three evolutionary channels. Using the calculated birth rate, we compare our results to the LISA sensitivity curve and the foreground noise floor of CDWDs. We find that our estimate for the number of CDWD sources that can be detected by the LISA detector is greater than 10,000. We also find that the detectable CDWDs are produced via the CE+CE channel and we analyze the fraction of the detectable CDWDs that are double helium (He+He), or carbon-oxygen plus helium (CO+He) WD binary systems.
Gravitational Waves in Effective Quantum Gravity
NASA Astrophysics Data System (ADS)
Calmet, Xavier; Kuntz, Iberê; Mohapatra, Sonali
2016-08-01
In this short paper we investigate quantum gravitational effects on Einstein's equations using Effective Field Theory techniques. We consider the leading order quantum gravitational correction to the wave equation. Besides the usual massless mode, we find a pair of modes with complex masses. These massive particles have a width and could thus lead to a damping of gravitational waves if excited in violent astrophysical processes producing gravitational waves such as e.g. black hole mergers. We discuss the consequences for gravitational wave events such as GW 150914 recently observed by the Advanced LIGO collaboration.
Gravitational Waves from Core Collapse Supernovae
Yakunin, Konstantin; Marronetti, Pedro; Mezzacappa, Anthony; Bruenn, S. W.; Lee, Ching-Tsai; Chertkow, Merek A; Hix, William Raphael; Blondin, J. M.; Lentz, Eric J; Messer, Bronson; Yoshida, S.
2010-01-01
We present the gravitational wave signatures for a suite of axisymmetric core collapse supernova models with progenitor masses between 12 and 25 M{sub odot}. These models are distinguished by the fact that they explode and contain essential physics (in particular, multi-frequency neutrino transport and general relativity) needed for a more realistic description. Thus, we are able to compute complete waveforms (i.e. through explosion) based on non-parameterized, first-principles models. This is essential if the waveform amplitudes and time scales are to be computed more precisely. Fourier decomposition shows that the gravitational wave signals we predict should be observable by AdvLIGO across the range of progenitors considered here. The fundamental limitation of these models is in their imposition of axisymmetry. Further progress will require counterpart three-dimensional models.
Listening to the Universe with gravitational waves
NASA Astrophysics Data System (ADS)
Sathyaprakash, B. S.
2016-07-01
The discovery of gravitational waves by the twin LIGO detectors in September 2015 has opened a new window for observational astronomy. The coming years will witness the emergence of other detectors such as Advanced Virgo, KAGRA and LIGO-India. The worldwide network of these detectors will not only observe binary black holes, which we now know will be the dominant sources, but other sources such as binary neutron stars, neutron star-black hole binaries, supernovae, stochastic backgrounds and unknown sources that we do not know yet. In my talk I will describe how gravitational wave observations will help us gain deeper insights into fundamental physics, astrophysics and cosmology in the coming years and decades.
Suppression of the Primordial Gravitational Waves
NASA Astrophysics Data System (ADS)
Tumurtushaa, Gansukh; Koh, Seoktae; Lee, Bum-Hoon
2016-07-01
We study the primordial gravitational waves induced by space-space condensate inflation model. For modes that cross the comoving horizon during matter dominated era, we calculate the energy spectrum of gravitational waves. The energy spectrum of gravitational waves for our model has significantly suppressed in the low frequency range. The suppression occurs due to the phase transition during the early evolution of the Universe and depends on model parameter.
Gravitational Wave Astrophysics: Opening the New Frontier
NASA Technical Reports Server (NTRS)
Centrella, Joan
2011-01-01
A new era in time-domain astronomy will begin when the gravitational wave window onto the universe opens in approx. 5 years, as ground-based detectors make the first detections in the high-frequency regime. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters through dense, obscured regions across cosmic time. This talk will explore gravitational waves as cosmic messengers, highlighting key sources and opportunities for multimessenger astronomy across the gravitational wave spectrum.
Gravitational Wave Astrophysics: Opening the New Frontier
NASA Technical Reports Server (NTRS)
Centrella, Joan
2012-01-01
A new era in astronomy will begin when the gravitational wave window onto the universe opens in approx. 5 years, as ground-based detectors make the first detections in the high-frequency regime. Since the universe is nearly transparent to gravitational waves, these signals carry direct information about their sources - such as masses, spins, luminosity distances, and orbital parameters - through dense, obscured regions across cosmic time. This talk will explore gravitational waves as cosmic messengers, highlighting key sources and opportunities for multi-messenger astronomy across the gravitational wave spectrum.
Gravitational Wave Astrophysics: Opening the New Frontier
NASA Technical Reports Server (NTRS)
Centrella, Joan
2011-01-01
A new era in astronomy will begin when the gravitational wave window onto the universe opens in approx. 5 years) as ground-based detectors make the first detections in the high-frequency regime. Since the universe is nearly transparent to gravitational waves) these signals carry direct information about their sources - such as masses) spins) luminosity distances) and orbital parameters - through dense) obscured regions across cosmic time. This talk will explore gravitational waves as cosmic messengers) highlighting key sources and opportunities for multi-messenger astronomy across the gravitational wave spectrum.
Interaction of gravitational waves with magnetic and electric fields
Barrabes, C.; Hogan, P. A.
2010-03-15
The existence of large-scale magnetic fields in the universe has led to the observation that if gravitational waves propagating in a cosmological environment encounter even a small magnetic field then electromagnetic radiation is produced. To study this phenomenon in more detail we take it out of the cosmological context and at the same time simplify the gravitational radiation to impulsive waves. Specifically, to illustrate our findings, we describe the following three physical situations: (1) a cylindrical impulsive gravitational wave propagating into a universe with a magnetic field, (2) an axially symmetric impulsive gravitational wave propagating into a universe with an electric field and (3) a 'spherical' impulsive gravitational wave propagating into a universe with a small magnetic field. In cases (1) and (3) electromagnetic radiation is produced behind the gravitational wave. In case (2) no electromagnetic radiation appears after the wave unless a current is established behind the wave breaking the Maxwell vacuum. In all three cases the presence of the magnetic or electric fields results in a modification of the amplitude of the incoming gravitational wave which is explicitly calculated using the Einstein-Maxwell vacuum field equations.
Studying cosmological sources of gravitational waves
NASA Astrophysics Data System (ADS)
Corbin, Vincent Dominique Andre
This dissertation presents two aspects of the study of cosmology through gravitational waves. The first aspect involves direct observation of past eras of the Universe's formation. The detection of the Cosmic Microwave Background Radiation was one of the most important cosmological discoveries of the last century. With the development of interferometric gravitational wave detectors, we may be in a position to detect its gravitational equivalent in this century. The Cosmic Gravitational Background is likely to be isotropic and stochastic, making it difficult to distinguish from instrument noise. The contribution from the gravitational background can be isolated by cross-correlating the signals from two or more independent detectors. Here we extend previous studies that considered the cross-correlation of two Michelson channels by calculating the optimal signal to noise ratio that can be achieved by combining the full set of interferometry variables that are available with a six link triangular interferometer. We apply our results to the detector design described in the Big Bang Observer mission concept study and find that it could detect a background with Ogw > 2.2 x 10 --17. The second aspect consists in studying astrophysical sources that detain crucial information on the Universe's evolution. We focus our attention on black holes binary sytems. These systems contain information on the rate of merger between galaxies, which in turn is key to unlock the mystery of inflation. Pulsar timing is a promising technique for detecting low frequency sources of gravitational waves, such as massive and supermassive black hole binaries. Here we show that the timing data from an array of pulsars can be used to recover the physical parameters describing an individual black hole binary to good accuracy, even for moderately strong signals. A novel aspect of our analysis is that we include the distance to each pulsar as a search parameter, which allows us to utilize the full
Gravitational waves in bimetric MOND
NASA Astrophysics Data System (ADS)
Milgrom, Mordehai
2014-01-01
I consider the weak-field limit (WFL) of the bimetric, relativistic formulation of the modified Newtonian dynamics (BIMOND)—the lowest order in the small departures hμν=gμν-ημν, h stretchy="false">^μν=g stretchy="false">^μν-ημν from double Minkowski space-time. In particular, I look at propagating solutions, for a favorite subclass of BIMOND. The WFL splits into two sectors for two linear combinations, hμν±, of hμν and h stretchy="false">^μν. The hμν+ sector is equivalent to the WFL of general relativity (GR), with its gauge freedom, and has the same vacuum gravitational waves. The hμν- sector is fully nonlinear even for the weakest hμν-, and inherits none of the coordinate gauge freedom. The equations of motion are scale invariant in the deep-MOND limit of purely gravitational systems. In these last two regards, the BIMOND WFL is greatly different from that of other bimetric theories studied to date. Despite the strong nonlinearity, an arbitrary pair of harmonic GR wave packets of hμν and h stretchy="false">^μν moving in the same direction, is a solution of the (vacuum) BIMOND WFL.
Polnarev, A. G.; Baskaran, D.
2008-06-15
In the current work we investigate the propagation of electromagnetic waves in the field of gravitational waves. Starting with the simple case of an electromagnetic wave traveling in the field of a plane monochromatic gravitational wave, we introduce the concept of the surfing effect and analyze its physical consequences. We then generalize these results to an arbitrary gravitational wave field. We show that, due to the transverse nature of gravitational waves, the surfing effect leads to significant observable consequences only if the velocity of gravitational waves deviates from the speed of light. This fact can help to place an upper limit on the deviation of gravitational wave velocity from the speed of light. The microarcsecond resolution promised by the upcoming precision interferometry experiments allow one to place stringent upper limits on {epsilon}=(v{sub gw}-c)/c as a function of the energy density parameter for gravitational waves {omega}{sub gw}. For {omega}{sub gw}{approx_equal}10{sup -10} this limit amounts to {epsilon} < or approx. 2{center_dot}10{sup -2}.
Frontiers in gravitational physics
NASA Astrophysics Data System (ADS)
Dutta, Koushik
In this thesis we present three research projects in classical General Relativity and Cosmology. In the first part of the thesis we investigate the definition of gravitational charge corresponding to the asymptotic boost symmetry of a spacetime and derive its role in the first law of black hole thermodynamics. In the cosmology part, we investigate the role of a scalar field in the early and late time evolution of the Universe. We find out observational constraints on the pseudo Nambu Goldstone Boson quintessence model using the latest supernova and Cosmic Microwave Background (CMB) data. In an attempt to explain a particular anomaly in the latest CMB data, we propose a modification to the standard single field inflation based on the initial kinetic energy domination with anisotropic initial conditions. Predictions of this mechanism can be tested in future data analysis.
Inflationary gravitational waves and the evolution of the early universe
Jinno, Ryusuke; Moroi, Takeo; Nakayama, Kazunori E-mail: moroi@hep-th.phys.s.u-tokyo.ac.jp
2014-01-01
We study the effects of various phenomena which may have happened in the early universe on the spectrum of inflationary gravitational waves. The phenomena include phase transitions, entropy productions from non-relativistic matter, the production of dark radiation, and decoupling of dark matter/radiation from thermal bath. These events can create several characteristic signatures in the inflationary gravitational wave spectrum, which may be direct probes of the history of the early universe and the nature of high-energy physics.
Gravitational Wave Science: Challenges for Numerical Relativistic Astrophysics
NASA Technical Reports Server (NTRS)
Cenrella, Joan
2005-01-01
Gravitational wave detectors on earth and in space will open up a new observational window on the universe. The new information about astrophysics and fundamental physics these observations will bring is expected to pose exciting challenges. This talk will provide an overview of this emerging area of gravitational wave science, with a focus on the challenges it will bring for numerical relativistic astrophysics and a look at some recent results.
Yunes, Nicolas; O'Shaughnessy, Richard; Owen, Benjamin J.; Alexander, Stephon
2010-09-15
Gravitational parity violation is a possibility motivated by particle physics, string theory, and loop quantum gravity. One effect of it is amplitude birefringence of gravitational waves, whereby left and right circularly polarized waves propagate at the same speed but with different amplitude evolution. Here we propose a test of this effect through coincident observations of gravitational waves and short gamma-ray bursts from binary mergers involving neutron stars. Such gravitational waves are highly left or right circularly polarized due to the geometry of the merger. Using localization information from the gamma-ray burst, ground-based gravitational wave detectors can measure the distance to the source with reasonable accuracy. An electromagnetic determination of the redshift from an afterglow or host galaxy yields an independent measure of this distance. Gravitational parity violation would manifest itself as a discrepancy between these two distance measurements. We exemplify such a test by considering one specific effective theory that leads to such gravitational parity violation, Chern-Simons gravity. We show that the advanced LIGO-Virgo network and all-sky gamma-ray telescopes can be sensitive to the propagating sector of Chern-Simons gravitational parity violation to a level roughly 2 orders of magnitude better than current stationary constraints from the LAGEOS satellites.
Gravitational Wave Astronomy:The High Frequency Window
NASA Astrophysics Data System (ADS)
Andersson, Nils; Kokkotas, Kostas D.
As several large scale interferometers are beginning to take data at sensitivities where astrophysical sources are predicted, the direct detection of gravitational waves may well be imminent. This would (finally) open the long anticipated gravitational-wave window to our Universe, and should lead to a much improved understanding of the most violent processes imaginable; the formation of black holes and neutron stars following core collapse supernovae and the merger of compact objects at the end of binary inspiral. Over the next decade we can hope to learn much about the extreme physics associated with, in particular, neutron stars. This contribution is divided in two parts. The first part provides a text-book level introduction to gravitational radiation. The key concepts required for a discussion of gravitational-wave physics are introduced. In particular, the quadrupole formula is applied to the anticipated bread-and-butter source for detectors like LIGO, GEO600, EGO and TAMA300: inspiralling compact binaries. The second part provides a brief review of high frequency gravitational waves. In the frequency range above (say) 100 Hz, gravitational collapse, rotational instabilities and oscillations of the remnant compact objects are potentially important sources of gravitational waves. Significant and unique information concerning the various stages of collapse, the evolution of protoneutron stars and the details of the supranuclear equation of state of such objects can be drawn from careful study of the gravitational-wave signal. As the amount of exciting physics one may be able to study via the detections of gravitational waves from these sources is truly inspiring, there is strong motivation for the development of future generations of ground based detectors sensitive in the range from hundreds of Hz to several kHz.
An heuristic introduction to gravitational waves
NASA Astrophysics Data System (ADS)
Sandberg, Vernon D.
1983-03-01
We describe in physical terms the phenomenon of gravitational waves. The philosophy of William Gilbert is used.1 ``Since in the discovery of secret things and in the investigation of hidden causes, stronger reasons are obtained from sure experiments and demonstrated arguments than from probable conjectures and the opinions of philosophical speculators of the common sort; therefore to the end that the noble substance of that great loadstone, our common mother (the earth), still quite unknown, and also the forces extraordinary and exalted of this globe may the better be understood...''
Gravitational-wave Mission Study
NASA Technical Reports Server (NTRS)
Mcnamara, Paul; Jennrich, Oliver; Stebbins, Robin T.
2014-01-01
In November 2013, ESA selected the science theme, the "Gravitational Universe," for its third large mission opportunity, known as L3, under its Cosmic Vision Programme. The planned launch date is 2034. ESA is considering a 20% participation by an international partner, and NASA's Astrophysics Division has indicated an interest in participating. We have studied the design consequences of a NASA contribution, evaluated the science benefits and identified the technology requirements for hardware that could be delivered by NASA. The European community proposed a strawman mission concept, called eLISA, having two measurement arms, derived from the well studied LISA (Laser Interferometer Space Antenna) concept. The US community is promoting a mission concept known as SGO Mid (Space-based Gravitational-wave Observatory Mid-sized), a three arm LISA-like concept. If NASA were to partner with ESA, the eLISA concept could be transformed to SGO Mid by the addition of a third arm, augmenting science, reducing risk and reducing non-recurring engineering costs. The characteristics of the mission concepts and the relative science performance of eLISA, SGO Mid and LISA are described. Note that all results are based on models, methods and assumptions used in NASA studies
Relic Gravitational Waves and Their Detection
NASA Astrophysics Data System (ADS)
Grishchuk, Leonid P.
The range of expected amplitudes and spectral slopes of relic (squeezed) gravitational waves, predicted by theory and partially supported by observations, is within the reach of sensitive gravity-wave detectors. In the most favorable case, the detection of relic gravitational waves can be achieved by the cross-correlation of outputs of the initial laser interferometers in LIGO, VIRGO, GEO600. In the more realistic case, the sensitivity of advanced ground-based and space-based laser interferometers will be needed. The specific statistical signature of relic gravitational waves, associated with the phenomenon of squeezing, is a potential reserve for further improvement of the signal to noise ratio.
Gravitaton Wave and Gravitational-Photon Interaction
NASA Astrophysics Data System (ADS)
Khasanov, Kholmurad
2013-06-01
Gravitation waves and gravitational-photon interaction with high energy photons emission is found experimentally. Super-compressibility phenomenon was studied. Spectral investigations of supersonic jets and incandescent nichrome thread and wolfram spiral were studied. The shifting of the emission spectrum was detected depending on vector of gravity. The increasing frequency of light emitted against gravity vector is measured. Uneven along the spectrum character of intensity increasing is found. Generation of short-wavelength component of the spectrum is observed in case of more power of heating. The measurements show that presented interactions have resonance nature. Our experiments demonstrate the existence resonance nature. Our experiments demonstrate the gravitation wave and generation and existence of gravitational-photon interactions. From left to right: Fig. 1-2. Visualization of the gravitation wave. Fig. 3-5. Gravitational-photon interaction in HF field.
Optics in a nonlinear gravitational plane wave
NASA Astrophysics Data System (ADS)
Harte, Abraham I.
2015-09-01
Gravitational waves can act like gravitational lenses, affecting the observed positions, brightnesses, and redshifts of distant objects. Exact expressions for such effects are derived here in general relativity, allowing for arbitrarily-moving sources and observers in the presence of plane-symmetric gravitational waves. At least for freely falling sources and observers, it is shown that the commonly-used predictions of linear perturbation theory can be generically overshadowed by nonlinear effects; even for very weak gravitational waves, higher-order perturbative corrections involve secularly-growing terms which cannot necessarily be neglected when considering observations of sufficiently distant sources. Even on more moderate scales where linear effects remain at least marginally dominant, nonlinear corrections are qualitatively different from their linear counterparts. There is a sense in which they can, for example, mimic the existence of a third type of gravitational wave polarization.
Gravitational lensing of gravitational waves from merging neutron star binaries
Wang, Yun; Stebbins, Albert; Turner, Edwin L.
1996-05-01
We discuss the gravitational lensing of gravitational waves from merging neutron star binaries, in the context of advanced LIGO type gravitational wave detectors. We consider properties of the expected observational data with cut on the signal-to-noise ratio \\rho, i.e., \\rho>\\rho_0. An advanced LIGO should see unlensed inspiral events with a redshift distribution with cut-off at a redshift z_{\\rm max} < 1 for h \\leq 0.8. Any inspiral events detected at z>z_{\\rm max} should be lensed. We compute the expected total number of events which are present due to gravitational lensing and their redshift distribution for an advanced LIGO in a flat Universe. If the matter fraction in compact lenses is close to 10\\%, an advanced LIGO should see a few strongly lensed events per year with \\rho >5.
Transient multimessenger astronomy with gravitational waves
NASA Astrophysics Data System (ADS)
Márka, S.; LIGO Scientific Collaboration; Virgo Collaboration
2011-06-01
Comprehensive multimessenger astronomy with gravitational waves is a pioneering field bringing us interesting results and presenting us with exciting challenges for the future. During the era of the operation of advanced interferometric gravitational wave detectors, we will have the opportunity to investigate sources of gravitational waves that are also expected to be observable through other messengers, such as gamma rays, x-rays, optical, radio, and/or neutrino emission. Multimessenger searches for gravitational waves with the LIGO-GEO600-Virgo interferometer network have already produced insights on cosmic events and it is expected that the simultaneous observation of electromagnetic or neutrino emission could be a crucial aspect for the first direct detection of gravitational waves in the future. Trigger time, direction and expected frequency range enhances our ability to search for gravitational wave signatures with amplitudes closer to the noise floor of the detector. Furthermore, multimessenger observations will enable the extraction of otherwise unaccessible scientific insight. We summarize the status of transient multimessenger detection efforts as well as mention some of the open questions that might be resolved by advanced or third generation gravitational wave detector networks.
Astrophysically Triggered Searches for Gravitational Waves
NASA Astrophysics Data System (ADS)
Marka, Zsuzsa
2010-02-01
Many expected sources of gravitational waves are observable in more traditional channels, via gamma rays, X-rays, optical, radio, or neutrino emission. Some of these channels are already being used in searches for gravitational waves with the LIGO-GEO600-Virgo interferometer network, and others are currently being incorporated into new or planned searches. Astrophysical targets include gamma-ray bursts, soft-gamma repeaters, supernovae, and glitching pulsars. The observation of electromagnetic or neutrino emission simultaneously with gravitational waves could be crucial for the first direct detection of gravitational waves. Information on the progenitor, such as trigger time, direction and expected frequency range, can enhance our ability to identify gravitational wave signatures with amplitude close to the noise floor of the detector. Furthermore, combining gravitational waves with electromagnetic and neutrino observations will enable the extraction of scientific insight that was hidden from us before. We will discuss the status for astrophysically triggered searches with the LIGO-GEO600-Virgo network and the science goals and outlook for the second and third generation gravitational wave detector era. )
The Japanese space gravitational wave antenna; DECIGO
NASA Astrophysics Data System (ADS)
Kawamura, S.; Ando, M.; Nakamura, T.; Tsubono, K.; Tanaka, T.; Funaki, I.; Seto, N.; Numata, K.; Sato, S.; Ioka, K.; Kanda, N.; Takashima, T.; Agatsuma, K.; Akutsu, T.; Akutsu, T.; Aoyanagi, K.-s.; Arai, K.; Arase, Y.; Araya, A.; Asada, H.; Aso, Y.; Chiba, T.; Ebisuzaki, T.; Enoki, M.; Eriguchi, Y.; Fujimoto, M.-K.; Fujita, R.; Fukushima, M.; Futamase, T.; Ganzu, K.; Harada, T.; Hashimoto, T.; Hayama, K.; Hikida, W.; Himemoto, Y.; Hirabayashi, H.; Hiramatsu, T.; Hong, F.-L.; Horisawa, H.; Hosokawa, M.; Ichiki, K.; Ikegami, T.; Inoue, K. T.; Ishidoshiro, K.; Ishihara, H.; Ishikawa, T.; Ishizaki, H.; Ito, H.; Itoh, Y.; Kamagasako, S.; Kawashima, N.; Kawazoe, F.; Kirihara, H.; Kishimoto, N.; Kiuchi, K.; Kobayashi, S.; Kohri, K.; Koizumi, H.; Kojima, Y.; Kokeyama, K.; Kokuyama, W.; Kotake, K.; Kozai, Y.; Kudoh, H.; Kunimori, H.; Kuninaka, H.; Kuroda, K.; Maeda, K.-i.; Matsuhara, H.; Mino, Y.; Miyakawa, O.; Miyoki, S.; Morimoto, M. Y.; Morioka, T.; Morisawa, T.; Moriwaki, S.; Mukohyama, S.; Musha, M.; Nagano, S.; Naito, I.; Nakagawa, N.; Nakamura, K.; Nakano, H.; Nakao, K.; Nakasuka, S.; Nakayama, Y.; Nishida, E.; Nishiyama, K.; Nishizawa, A.; Niwa, Y.; Ohashi, M.; Ohishi, N.; Ohkawa, M.; Okutomi, A.; Onozato, K.; Oohara, K.; Sago, N.; Saijo, M.; Sakagami, M.; Sakai, S.-i.; Sakata, S.; Sasaki, M.; Sato, T.; Shibata, M.; Shinkai, H.; Somiya, K.; Sotani, H.; Sugiyama, N.; Suwa, Y.; Tagoshi, H.; Takahashi, K.; Takahashi, K.; Takahashi, T.; Takahashi, H.; Takahashi, R.; Takahashi, R.; Takamori, A.; Takano, T.; Taniguchi, K.; Taruya, A.; Tashiro, H.; Tokuda, M.; Tokunari, M.; Toyoshima, M.; Tsujikawa, S.; Tsunesada, Y.; Ueda, K.-i.; Utashima, M.; Yamakawa, H.; Yamamoto, K.; Yamazaki, T.; Yokoyama, J.; Yoo, C.-M.; Yoshida, S.; Yoshino, T.
2008-07-01
DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry-Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-DECIGO first and finally DECIGO in 2024.
Binary Black Holes and Gravitational Waves
NASA Technical Reports Server (NTRS)
Centrella, Joan
2007-01-01
The final merger of two black holes releases a tremendous amount of energy, more than the combined light from all the stars in the visible universe. This energy is emitted in the form of gravitational waves, and observing these sources with gravitational wave detectors such as LIGO and LISA requires that we know the pattern or fingerprint of the radiation emitted. Since black hole mergers take place in regions of extreme gravitational fields, we need to solve Einstein's equations of general relativity on a computer in order to calculate these wave patterns.
PREFACE: 8th Edoardo Amaldi Conference on Gravitational Waves
NASA Astrophysics Data System (ADS)
Marka, Zsuzsa; Marka, Szabolcs
2010-04-01
multimessenger approaches to gravitational wave detection also received special attention at the meeting. For the first time in the history of Amaldi conferences, plenary and contributed sessions were held to transfer ideas and experience gained with gravitational wave science inspired education and outreach projects. Additionally, Columbia University faculties working in frontier fields, which currently may not have direct connection to the field of gravitational wave science, gave enthralling presentations in the form of a 'wake-up' lecture series. The meeting also facilitated the exchange of scientific results and new ideas among all members of gravitational wave experiment collaborations and the gravitational wave theory community. Additionally, future directions in gravitational wave detection were discussed in a special session dedicated to the Gravitational Wave International Committee Roadmap. A highly entertaining and inspiring public talk titled "Songs from Space: Black Holes and the Big Bang in Audio" was given by Janna Levin and it attracted over 300 young and old science enthusiasts from and around New York City. This special issue of Classical and Quantum Gravity (Volume 27, Number 8, 2010) is published as the proceedings of Amaldi8. It contains the overview articles by invited plenary speakers, and some of the highlights of the meeting as selected by session chairs and organizers. Other Amaldi8 talks and posters appear in the refereed issue of the electronic Journal of Physics: Conference Series. This issue of CQG and the JPCS issue are electronically linked. The conference organizers gratefully acknowledge the financial support of Columbia University in the City of New York, the International Union of Pure and Applied Physics and the United States National Science Foundation. We would like to thank the Gravitational Wave International Committee for the scientific oversight, the Local Organizing Committee for the program selection, and the session chairs for the
Gravitational wave astronomy: the current status
NASA Astrophysics Data System (ADS)
Blair, David; Ju, Li; Zhao, ChunNong; Wen, LinQing; Chu, Qi; Fang, Qi; Cai, RongGen; Gao, JiangRui; Lin, XueChun; Liu, Dong; Wu, Ling-An; Zhu, ZongHong; Reitze, David H.; Arai, Koji; Zhang, Fan; Flaminio, Raffaele; Zhu, XingJiang; Hobbs, George; Manchester, Richard N.; Shannon, Ryan M.; Baccigalupi, Carlo; Gao, Wei; Xu, Peng; Bian, Xing; Cao, ZhouJian; Chang, ZiJing; Dong, Peng; Gong, XueFei; Huang, ShuangLin; Ju, Peng; Luo, ZiRen; Qiang, Li'E.; Tang, WenLin; Wan, XiaoYun; Wang, Yue; Xu, ShengNian; Zang, YunLong; Zhang, HaiPeng; Lau, Yun-Kau; Ni, Wei-Tou
2015-12-01
In the centenary year of Einstein's General Theory of Relativity, this paper reviews the current status of gravitational wave astronomy across a spectrum which stretches from attohertz to kilohertz frequencies. Sect. 1 of this paper reviews the historical development of gravitational wave astronomy from Einstein's first prediction to our current understanding the spectrum. It is shown that detection of signals in the audio frequency spectrum can be expected very soon, and that a north-south pair of next generation detectors would provide large scientific benefits. Sect. 2 reviews the theory of gravitational waves and the principles of detection using laser interferometry. The state of the art Advanced LIGO detectors are then described. These detectors have a high chance of detecting the first events in the near future. Sect. 3 reviews the KAGRA detector currently under development in Japan, which will be the first laser interferometer detector to use cryogenic test masses. Sect. 4 of this paper reviews gravitational wave detection in the nanohertz frequency band using the technique of pulsar timing. Sect. 5 reviews the status of gravitational wave detection in the attohertz frequency band, detectable in the polarisation of the cosmic microwave background, and discusses the prospects for detection of primordial waves from the big bang. The techniques described in sects. 1-5 have already placed significant limits on the strength of gravitational wave sources. Sects. 6 and 7 review ambitious plans for future space based gravitational wave detectors in the millihertz frequency band. Sect. 6 presents a roadmap for development of space based gravitational wave detectors by China while sect. 7 discusses a key enabling technology for space interferometry known as time delay interferometry.
The Loudest Gravitational Wave Events
NASA Astrophysics Data System (ADS)
Chen, Hsin-Yu; Holz, Daniel
2014-03-01
Compact binary coalescences are likely to be the source of the first gravitational wave (GW) detections. While most Advanced LIGO-Virgo detections are expected to have signal-to-noise ratios (SNR) near the detection threshold, there will be a distribution of events to higher SNR. Assuming the space density of the sources is uniform in the nearby Universe, we derive the universal distribution of SNR in an arbitrary GW network, as well as the SNR distribution of the loudest event. These distributions only depend on the detection threshold and the number of detections; they are independent of the detector network, sensitivity, and the distribution of source variables such as the binary masses and spins. We also derive the SNR distribution for each individual detector within a network as a function of the detector orientation. We find that, in 90% of cases, the loudest event out of the first four Advanced LIGO-Virgo detections should be louder than SNR of 15.8 (for a threshold of 12), increasing to an SNR of 31 for 40 detections. We expect these loudest events to provide the best constraints on their source parameters, and therefore play an important role in extracting astrophysics from GW sources.
Polarized gravitational waves from cosmological phase transitions
NASA Astrophysics Data System (ADS)
Kisslinger, Leonard; Kahniashvili, Tina
2015-08-01
We estimate the degree of circular polarization for the gravitational waves generated during the electroweak and QCD phase transitions from the kinetic and magnetic helicity generated by bubble collisions during those cosmological phase transitions.
LISA: Detecting Gravitational Waves from Space
NASA Technical Reports Server (NTRS)
Livas, Jeff
2009-01-01
The laser interferometer space antenna (LISA), a joint NASA/ESA mission, will be the first dedicated gravitational wave detector in space. This presentation will provide a tutorial of the LISA measurement concept.
Gravitational Waves: A New Observational Window
NASA Technical Reports Server (NTRS)
Camp, Jordan B.
2010-01-01
The era of gravitational wave astronomy is rapidly approaching, with a likely start date around the middle of this decade ' Gravitational waves, emitted by accelerated motions of very massive objects, provide detailed information about strong-field gravity and its sources, including black holes and neutron stars, that electromagnetic probes cannot access. In this talk I will discuss the anticipated sources and the status of the extremely sensitive detectors (both ground and space based) that will make gravitational wave detections possible. As ground based detectors are now taking data, I will show some initial science results related to measured upper limits on gravitational wave signals. Finally Z will describe new directions including advanced detectors and joint efforts with other fields of astronomy.
Gravitational Waves and Time Domain Astronomy
NASA Technical Reports Server (NTRS)
Centrella, Joan; Nissanke, Samaya; Williams, Roy
2012-01-01
The gravitational wave window onto the universe will open in roughly five years, when Advanced LIGO and Virgo achieve the first detections of high frequency gravitational waves, most likely coming from compact binary mergers. Electromagnetic follow-up of these triggers, using radio, optical, and high energy telescopes, promises exciting opportunities in multi-messenger time domain astronomy. In the decade, space-based observations of low frequency gravitational waves from massive black hole mergers, and their electromagnetic counterparts, will open up further vistas for discovery. This two-part workshop featured brief presentations and stimulating discussions on the challenges and opportunities presented by gravitational wave astronomy. Highlights from the workshop, with the emphasis on strategies for electromagnetic follow-up, are presented in this report.
Gravitational Wave Detection with Atom Interferometry
Dimopoulos, Savas; Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.; Rajendran, Surjeet; /SLAC /Stanford U., Phys. Dept.
2008-01-23
We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10m atom interferometer presently under construction. The terrestrial experiment can operate with strain sensitivity {approx} 10{sup -19}/{radical}Hz in the 1 Hz-10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment probes the same frequency spectrum as LISA with better strain sensitivity {approx} 10{sup -20}/{radical}Hz. Each configuration compares two widely separated atom interferometers run using common lasers. The effect of the gravitational waves on the propagating laser field produces the main effect in this configuration and enables a large enhancement in the gravitational wave signal while significantly suppressing many backgrounds. The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations and acceleration noise, and reduces spacecraft control requirements.
Gravitational waves from collapsing domain walls
Hiramatsu, Takashi; Kawasaki, Masahiro; Saikawa, Ken'ichi E-mail: kawasaki@icrr.u-tokyo.ac.jp
2010-05-01
We study the production of gravitational waves from cosmic domain walls created during phase transition in the early universe. We investigate the process of formation and evolution of domain walls by running three dimensional lattice simulations. If we introduce an approximate discrete symmetry, walls become metastable and finally disappear. This process might occur by a pressure difference between two vacua if a quantum tunneling is neglected. We calculate the spectrum of gravitational waves produced by collapsing metastable domain walls. Extrapolating the numerical results, we find that the signal of gravitational waves produced by domain walls whose energy scale is around 10{sup 10}-10{sup 12}GeV will be observable in the next generation gravitational wave interferometers.
Transformations of asymptotic gravitational-wave data
NASA Astrophysics Data System (ADS)
Boyle, Michael
2016-04-01
Gravitational-wave data is gauge dependent. While we can restrict the class of gauges in which such data may be expressed, there will still be an infinite-dimensional group of transformations allowed while remaining in this class, and almost as many different—though physically equivalent—waveforms as there are transformations. This paper presents a method for calculating the effects of the most important transformation group, the Bondi-Metzner-Sachs (BMS) group, consisting of rotations, boosts, and supertranslations (which include time and space translations as special cases). To a reasonable approximation, these transformations result in simple coupling between the modes in a spin-weighted spherical-harmonic decomposition of the waveform. It is shown that waveforms from simulated compact binaries in the publicly available SXS waveform catalog contain unmodeled effects due to displacement and drift of the center of mass, accounting for mode mixing at typical levels of 1%. However, these effects can be mitigated by measuring the average motion of the system's center of mass for a portion of the inspiral, and applying the opposite transformation to the waveform data. More generally, controlling the BMS transformations will be necessary to eliminate the gauge ambiguity inherent in gravitational-wave data for both numerical and analytical waveforms. Open-source code implementing BMS transformations of waveforms is supplied along with this paper in the supplemental materials.
The pregalactic cosmic gravitational wave background
NASA Technical Reports Server (NTRS)
Matzner, Richard A.
1989-01-01
An outline is given that estimates the expected gravitational wave background, based on plausible pregalactic sources. Some cosmologically significant limits can be put on incoherent gravitational wave background arising from pregalactic cosmic evolution. The spectral region of cosmically generated and cosmically limited radiation is, at long periods, P greater than 1 year, in contrast to more recent cosmological sources, which have P approx. 10 to 10(exp -3).
Gravitational wave detection in the laboratory.
NASA Astrophysics Data System (ADS)
Chen, Y. T.; Kawashima, N.; Othman, M.; Chia, S. P.; Karim, M.; Sanugi, B.; Lim, B. H.; Chong, K. K.
1998-09-01
After reviewing the research work of gravitational wave detection in the laboratory, particularly long base laser interferometer detectors, the authors report on the recent progress of gravitational wave detection using laser interferometer (Tianyin-100) in Malaysia. The authors also outline the brief plan for Tianyin-500 in the future as a full-scale observatory competitive to other projects such as Ligo, Geo600, etc.
Time Evolution of Pure Gravitational Waves
NASA Astrophysics Data System (ADS)
Miyama, S. M.
1981-03-01
Numerical solutions to the Einstein equations in the case of pure gravitational waves are given. The system is assumed to be axially symmetric and non-rotating. The time symmetric initial data and the conformally flat initial data are obtained by solving the constraint equations at t=0. The time evolution of these initial data depends strongly on the initial amplitude of the gravitational waves. In the case of the low initial amplitude, waves only disperse to null infinity. By comparing the initial gravitational energy with the total energy loss through an r=constant surface, it is concluded that the Newman-Penrose method and the Gibbon-Hawking method are the most desirable for measuring the energy flux of gravitational radiation numerically. In the case that the initial ratio of the spatial extent of the gravitational waves to the Schwarzschild radius (M/2) is smaller than about 300, the waves collapse by themselves, leading to formation of a black hole. The analytic solutions of the linearized Einstein equations for the pure gravitational waves are also shown.
BOOK REVIEW Analysis of Gravitational-Wave Data Analysis of Gravitational-Wave Data
NASA Astrophysics Data System (ADS)
Fairhurst, Stephen
2010-12-01
The field of gravitational-wave data analysis has expanded greatly over the past decade and significant developments have been made in methods of analyzing the data taken by resonant bar and interferometric detectors, as well as analysis of mock LISA data. This book introduces much of the required theoretical background in gravitational physics, statistics and time series analysis before moving on to a discussion of gravitational-wave data analysis techniques themselves. The book opens with an overview of the theory of gravitational radiation, providing a comprehensive discussion of various introductory topics: linearized gravity, transverse traceless gauge, the effects of gravitational waves (via geodesic deviation), energy and momentum carried by the waves, and generation of gravitational waves. The second chapter provides an introduction to the various sources of gravitational waves, followed by more detailed expositions on some of the primary sources. For example, the description of compact binary coalescence is thorough and includes a brief exposition of the post-Newtonian formalism and the effective one body method. There also follows extended derivations of gravitational waves from distorted neutron stars, supernovae and a stochastic background. Chapter three provides an introduction to the statistical theory of signal detection, including a discussion of parameter estimation via the Fisher matrix formalism. This is presented from a very mathematical, postulate based, standpoint and I expect that even established gravitational-wave data analysts will find the derivations here more formal than they are used to. The discussion of likelihood ratio tests and the importance of prior probabilities are presented particularly clearly. The fourth chapter covers time series analysis, with power spectrum estimation, extraction of periodic signals and goodness of fit tests. Chapter five switches topics and gives the details of the response of gravitational-wave
Gravitational Waves from a Dark Phase Transition.
Schwaller, Pedro
2015-10-30
In this work, we show that a large class of models with a composite dark sector undergo a strong first order phase transition in the early Universe, which could lead to a detectable gravitational wave signal. We summarize the basic conditions for a strong first order phase transition for SU(N) dark sectors with n_{f} flavors, calculate the gravitational wave spectrum and show that, depending on the dark confinement scale, it can be detected at eLISA or in pulsar timing array experiments. The gravitational wave signal provides a unique test of the gravitational interactions of a dark sector, and we discuss the complementarity with conventional searches for new dark sectors. The discussion includes the twin Higgs and strongly interacting massive particle models as well as symmetric and asymmetric composite dark matter scenarios. PMID:26565451
Strong gravitational lensing of gravitational waves in Einstein Telescope
Piórkowska, Aleksandra; Biesiada, Marek; Zhu, Zong-Hong E-mail: marek.biesiada@us.edu.pl
2013-10-01
Gravitational wave experiments have entered a new stage which gets us closer to the opening a new observational window on the Universe. In particular, the Einstein Telescope (ET) is designed to have a fantastic sensitivity that will provide with tens or hundreds of thousand NS-NS inspiral events per year up to the redshift z = 2. Some of such events should be gravitationally lensed by intervening galaxies. We explore the prospects of observing gravitationally lensed inspiral NS-NS events in the Einstein telescope. Being conservative we consider the lens population of elliptical galaxies. It turns out that depending on the local insipral rate ET should detect from one per decade detection in the pessimistic case to a tens of detections per year for the most optimistic case. The detection of gravitationally lensed source in gravitational wave detectors would be an invaluable source of information concerning cosmography, complementary to standard ones (like supernovae or BAO) independent of the local cosmic distance ladder calibrations.
Gravitational wave science in the high school classroom
NASA Astrophysics Data System (ADS)
Farr, Benjamin; Schelbert, GionMatthias; Trouille, Laura
2012-10-01
This article describes a set of curriculum modifications designed to integrate gravitational wave science into a high school physics or astronomy curriculum. Gravitational wave scientists are on the verge of being able to detect extreme cosmic events, like the merger of two black holes, happening hundreds of millions of light years away. Their work has the potential to propel astronomy into a new era by providing an entirely new means of observing astronomical phenomena. Gravitational wave science encompasses astrophysics, physics, engineering, and quantum optics. As a result, this curriculum exposes students to the interdisciplinary nature of science. It also provides an authentic context for students to learn about astrophysical sources, data analysis techniques, cutting-edge detector technology, and error analysis.
Dissipation of modified entropic gravitational energy through gravitational waves
NASA Astrophysics Data System (ADS)
de Matos, Clovis Jacinto
2012-01-01
The phenomenological nature of a new gravitational type interaction between two different bodies derived from Verlinde's entropic approach to gravitation in combination with Sorkin's definition of Universe's quantum information content, is investigated. Assuming that the energy stored in this entropic gravitational field is dissipated under the form of gravitational waves and that the Heisenberg principle holds for this system, one calculates a possible value for an absolute minimum time scale in nature tau=15/16 Λ^{1/2}hbar G/c4˜9.27×10^{-105} seconds, which is much smaller than the Planck time t P =( ħG/ c 5)1/2˜5.38×10-44 seconds. This appears together with an absolute possible maximum value for Newtonian gravitational forces generated by matter Fg=32/30c7/Λ hbar G2˜ 3.84× 10^{165} Newtons, which is much higher than the gravitational field between two Planck masses separated by the Planck length F gP = c 4/ G˜1.21×1044 Newtons.
How to test gravitation theories by means of gravitational-wave measurements
NASA Technical Reports Server (NTRS)
Thorne, K. S.
1974-01-01
Gravitational-wave experiments are a potentially powerful tool for testing gravitation theories. Most theories in the literature predict rather different polarization properties for gravitational waves than are predicted by general relativity; and many theories predict anomalies in the propagation speeds of gravitational waves.
Nearby Stars as Gravitational Wave Detectors
NASA Astrophysics Data System (ADS)
Lopes, Ilídio; Silk, Joseph
2015-07-01
Sun-like stellar oscillations are excited by turbulent convection and have been discovered in some 500 main-sequence and sub-giant stars and in more than 12,000 red giant stars. When such stars are near gravitational wave sources, low-order quadrupole acoustic modes are also excited above the experimental threshold of detectability, and they can be observed, in principle, in the acoustic spectra of these stars. Such stars form a set of natural detectors to search for gravitational waves over a large spectral frequency range, from {10}-7 to {10}-2 Hz. In particular, these stars can probe the {10}-6-{10}-4 Hz spectral window which cannot be probed by current conventional gravitational wave detectors, such as the Square Kilometre Array and Evolved Laser Interferometer Space Antenna. The Planetary Transits and Oscillations of State (PLATO) stellar seismic mission will achieve photospheric velocity amplitude accuracy of {cm} {{{s}}}-1. For a gravitational wave search, we will need to achieve accuracies of the order of {10}-2 {cm} {{{s}}}-1, i.e., at least one generation beyond PLATO. However, we have found that multi-body stellar systems have the ideal setup for this type of gravitational wave search. This is the case for triple stellar systems formed by a compact binary and an oscillating star. Continuous monitoring of the oscillation spectra of these stars to a distance of up to a kpc could lead to the discovery of gravitational waves originating in our galaxy or even elsewhere in the universe. Moreover, unlike experimental detectors, this observational network of stars will allow us to study the progression of gravitational waves throughout space.
Gravitational waves in fourth order gravity
NASA Astrophysics Data System (ADS)
Capozziello, S.; Stabile, A.
2015-08-01
In the post-Minkowskian limit approximation, we study gravitational wave solutions for general fourth-order theories of gravity. Specifically, we consider a Lagrangian with a generic function of curvature invariants . It is well known that when dealing with General Relativity such an approach provides massless spin-two waves as propagating degree of freedom of the gravitational field while this theory implies other additional propagating modes in the gravity spectra. We show that, in general, fourth order gravity, besides the standard massless graviton is characterized by two further massive modes with a finite-distance interaction. We find out the most general gravitational wave solutions in terms of Green functions in vacuum and in presence of matter sources. If an electromagnetic source is chosen, only the modes induced by are present, otherwise, for any gravity model, we have the complete analogy with tensor modes of General Relativity. Polarizations and helicity states are classified in the hypothesis of plane wave.
Binary Black Holes and Gravitational Waves
NASA Technical Reports Server (NTRS)
Centrella, Joan
2007-01-01
The final merger of two black holes releases a tremendous amount of energy, more than the combined light from all the stars in the visible universe. This energy is emitted in the form of gravitational waves, and observing these sources with gravitational wave detectors such as LIGO and LISA requires that we know the pattern or fingerprint of the radiation emitted. Since black hole mergers take place in regions of extreme gravitational fields, we need to solve Einstein's equations of general relativity on a computer in order to calculate these wave patterns. For more than 30 years, scientists have tried to compute these wave patterns. However, their computer codes have been plagued by problems that caused them to crash. This situation has changed dramatically in the past 2 years, with a series of amazing breakthroughs. This discussion examines these gravitational patterns, showing how a spacetime is constructed on a computer to build a simulation laboratory for binary black hole mergers. The focus is on recent advances that are revealing these waveforms, and the dramatic new potential for discoveries that arises when these sources will be observed by the space-based gravitational wave detector LISA.
Phase transition dynamics and gravitational waves
Megevand, Ariel
2009-04-20
During a first-order phase transition, gravitational radiation is generated either by bubble collisions or by turbulence. For phase transitions which took place at the electroweak scale and beyond, the signal is expected to be within the sensitivity range of planned interferometers such as LISA or BBO. We review the generation of gravitational waves in a first-order phase transition and discuss the dependence of the spectrum on the dynamics of the phase transition.
Detecting stochastic backgrounds of gravitational waves with pulsar timing arrays
NASA Astrophysics Data System (ADS)
Siemens, Xavier
2016-03-01
For the past decade the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has been using the Green Bank Telescope and the Arecibo Observatory to monitor millisecond pulsars. NANOGrav, along with two other international collaborations, the European Pulsar Timing Array and the Parkes Pulsar Timing Array in Australia, form a consortium of consortia: the International Pulsar Timing Array (IPTA). The goal of the IPTA is to directly detect low-frequency gravitational waves which cause small changes to the times of arrival of radio pulses from millisecond pulsars. In this talk I will discuss the work of NANOGrav and the IPTA, as well as our sensitivity to stochastic backgrounds of gravitational waves. I will show that a detection of the background produced by supermassive black hole binaries is possible by the end of the decade. Supported by the NANOGrav Physics Frontiers Center.
LIGO - The Laser Interferometer Gravitational-Wave Observatory
NASA Technical Reports Server (NTRS)
Abramovici, Alex; Althouse, William E.; Drever, Ronald W. P.; Gursel, Yekta; Kawamura, Seiji; Raab, Frederick J.; Shoemaker, David; Sievers, Lisa; Spero, Robert E.; Thorne, Kip S.
1992-01-01
The goal of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Project is to detect and study astrophysical gravitational waves and use data from them for research in physics and astronomy. LIGO will support studies concerning the nature and nonlinear dynamics for gravity, the structures of black holes, and the equation of state of nuclear matter. It will also measure the masses, birth rates, collisions, and distributions of black holes and neutron stars in the universe and probe the cores of supernovae and the very early universe. The technology for LIGO has been developed during the past 20 years. Construction will begin in 1992, and under the present schedule, LIGO's gravitational-wave searches will begin in 1998.
GRAVITATIONAL WAVES OF JET PRECESSION IN GAMMA-RAY BURSTS
Sun Mouyuan; Liu Tong; Gu Weimin; Lu Jufu
2012-06-10
The physical nature of gamma-ray bursts (GRBs) is believed to involve an ultra-relativistic jet. The observed complex structure of light curves motivates the idea of jet precession. In this work, we study the gravitational waves of jet precession based on neutrino-dominated accretion disks around black holes, which may account for the central engine of GRBs. In our model, the jet and the inner part of the disk may precess along with the black hole, which is driven by the outer part of the disk. Gravitational waves are therefore expected to be significant from this black-hole-inner-disk precession system. By comparing our numerical results with the sensitivity of some detectors, we find that it is possible for DECIGO and BBO to detect such gravitational waves, particularly for GRBs in the Local Group.
Parametric resonance and cosmological gravitational waves
Sa, Paulo M.; Henriques, Alfredo B.
2008-03-15
We investigate the production of gravitational waves due to quantum fluctuations of the vacuum during the transition from the inflationary to the radiation-dominated eras of the universe, assuming this transition to be dominated by the phenomenon of parametric resonance. The energy spectrum of the gravitational waves is calculated using the method of continuous Bogoliubov coefficients, which avoids the problem of overproduction of gravitons at large frequencies. We found, on the sole basis of the mechanism of quantum fluctuations, that the resonance field leaves no explicit and distinctive imprint on the gravitational-wave energy spectrum, apart from an overall upward or downward translation. Therefore, the main features in the spectrum are due to the inflaton field, which leaves a characteristic imprint at frequencies of the order of MHz/GHz.
Gravitational wave experiments and early universe cosmology
NASA Astrophysics Data System (ADS)
Maggiore, M.
2000-07-01
Gravitational-wave experiments with interferometers and with resonant masses can search for stochastic backgrounds of gravitational waves of cosmological origin. We review both experimental and theoretical aspects of the search for these backgrounds. We give a pedagogical derivation of the various relations that characterize the response of a detector to a stochastic background. We discuss the sensitivities of the large interferometers under constructions (LIGO, VIRGO, GEO600, TAMA300, AIGO) or planned (Avdanced LIGO, LISA) and of the presently operating resonant bars, and we give the sensitivities for various two-detectors correlations. We examine the existing limits on the energy density in gravitational waves from nucleosynthesis, COBE and pulsars, and their effects on theoretical predictions. We discuss general theoretical principles for order-of-magnitude estimates of cosmological production mechanisms, and then we turn to specific theoretical predictions from inflation, string cosmology, phase transitions, cosmic strings and other mechanisms. We finally compare with the stochastic backgrounds of astrophysical origin.
Exploring Gravitational Waves in the Classroom
NASA Astrophysics Data System (ADS)
Cominsky, Lynn R.; McLin, Kevin M.; Peruta, Carolyn; Simonnet, Aurore
2016-04-01
On September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) received the first confirmed gravitational wave signals. Now known as GW150914 (for the date on which the signals were received), the event represents the coalescence of two black holes that were previously in mutual orbit. LIGO’s exciting discovery provides direct evidence of what is arguably the last major unconfirmed prediction of Einstein’s General Theory of Relativity. The Education and Public Outreach group at Sonoma State University has created an educator's guide that provides a brief introduction to LIGO and to gravitational waves, along with two simple demonstration activities that can be done in the classroom to engage students in understanding LIGO’s discovery. Additional resources have also been provided to extend student explorations of Einstein’s Universe.
General-relativistic astrophysics. [gravitational wave astronomy
NASA Technical Reports Server (NTRS)
Thorne, K. S.
1978-01-01
The overall relevance of general relativity to astrophysics is considered, and some of the knowledge about the ways in which general relativity should influence astrophysical systems is reviewed. Attention is focused primarily on finite-sized astrophysical systems, such as stars, globular clusters, galactic nuclei, and primordial black holes. Stages in the evolution of such systems and tools for studying the effects of relativistic gravity in these systems are examined. Gravitational-wave astronomy is discussed in detail, with emphasis placed on estimates of the strongest gravitational waves that bathe earth, present obstacles and future prospects for detection of the predicted waves, the theory of small perturbations of relativistic stars and black holes, and the gravitational waves such objects generate. Characteristics of waves produced by black-hole events in general, pregalactic black-hole events, black-hole events in galactic nuclei and quasars, black-hole events in globular clusters, the collapse of normal stars to form black holes or neutron stars, and corequakes in neutron stars are analyzed. The state of the art in gravitational-wave detection and characteristics of various types of detector are described.
Gravitational Waves from Coalescing Binary Black Holes: Theoretical and Experimental Challenges
None
2011-10-06
A network of ground-based interferometric gravitational wave detectors (LIGO/VIRGO/GEO/...) is currently taking data near its planned sensitivity. Coalescing black hole binaries are among the most promising, and most exciting, gravitational wave sources for these detectors. The talk will review the theoretical and experimental challenges that must be met in order to successfully detect gravitational waves from coalescing black hole binaries, and to be able to reliably measure the physical parameters of the source (masses, spins, ...).
Gravitational Waves from Coalescing Binary Black Holes: Theoretical and Experimental Challenges
2010-04-29
A network of ground-based interferometric gravitational wave detectors (LIGO/VIRGO/GEO/...) is currently taking data near its planned sensitivity. Coalescing black hole binaries are among the most promising, and most exciting, gravitational wave sources for these detectors. The talk will review the theoretical and experimental challenges that must be met in order to successfully detect gravitational waves from coalescing black hole binaries, and to be able to reliably measure the physical parameters of the source (masses, spins, ...).
Gravitational waves induced by spinor fields
NASA Astrophysics Data System (ADS)
Feng, Kaixi; Piao, Yun-Song
2015-07-01
In realistic model building, spinor fields with various masses are present. During inflation, a spinor field may induce gravitational waves as a second order effect. In this paper, we calculate the contribution of a single massive spinor field to the power spectrum of primordial gravitational wave by using a retarded Green propagator. We find that the correction is scale invariant and of order H4/MP4 for arbitrary spinor mass mψ. Additionally, we also observe that when mψ≳H , the dependence of correction on mψ/H is nontrivial.
Hough transform search for continuous gravitational waves
Krishnan, Badri; Papa, Maria Alessandra; Sintes, Alicia M.; Schutz, Bernard F.; Frasca, Sergio; Palomba, Cristiano
2004-10-15
This paper describes an incoherent method to search for continuous gravitational waves based on the Hough transform, a well-known technique used for detecting patterns in digital images. We apply the Hough transform to detect patterns in the time-frequency plane of the data produced by an earth-based gravitational wave detector. Two different flavors of searches will be considered, depending on the type of input to the Hough transform: either Fourier transforms of the detector data or the output of a coherent matched-filtering type search. We present the technical details for implementing the Hough transform algorithm for both kinds of searches, their statistical properties, and their sensitivities.
Gravitational waves in a de Sitter universe
NASA Astrophysics Data System (ADS)
Bishop, Nigel T.
2016-02-01
The construction of exact linearized solutions to the Einstein equations within the Bondi-Sachs formalism is extended to the case of linearization about de Sitter spacetime. The gravitational wave field measured by distant observers is constructed, leading to a determination of the energy measured by such observers. It is found that gravitational wave energy conservation does not normally apply to inertial observers but that it can be formulated for a class of accelerated observers, i.e., with worldlines that are timelike but not geodesic.
Gravitational Waves and Multi-Messenger Astronomy
NASA Technical Reports Server (NTRS)
Centrella, Joan M.
2010-01-01
Gravitational waves are produced by a wide variety of sources throughout the cosmos, including the mergers of black hole and neutron star binaries/compact objects spiraling into central black holes in galactic nuclei, close compact binaries/and phase transitions and quantum fluctuations in the early universe. Observing these signals can bring new, and often very precise, information about their sources across vast stretches of cosmic time. In this talk we will focus on thee opening of this gravitational-wave window on the universe, highlighting new opportunities for discovery and multi-messenger astronomy.
Gravitational Wave Detection: A Historical Perspective
NASA Astrophysics Data System (ADS)
Saulson, Peter
2015-04-01
The search for gravitational waves began at the Chapel Hill Conference in January 1957, and will reach a successful conclusion at a set of observatories around the globe about sixty years later. This talk will review the history of the early thought experiments, the program of resonant mass detectors (``Weber bars''), and the development of the large interferometric detectors like Advanced LIGO and Advanced Virgo that are, it is hoped, about to make the first detections of gravitational wave signals. I am pleased to acknowledge the support of the National Science Foundation for my research, most recently under NSF Grant PHY-1205835.
Gravitational wave bursts from cosmic strings
Damour; Vilenkin
2000-10-30
Cusps of cosmic strings emit strong beams of high-frequency gravitational waves (GW). As a consequence of these beams, the stochastic ensemble of gravitational waves generated by a cosmological network of oscillating loops is strongly non-Gaussian, and includes occasional sharp bursts that stand above the rms GW background. These bursts might be detectable by the planned GW detectors LIGO/VIRGO and LISA for string tensions as small as G&mgr; approximately 10(-13). The GW bursts discussed here might be accompanied by gamma ray bursts. PMID:11041921
Detection of gravitational waves: a hundred year journey
NASA Astrophysics Data System (ADS)
Mavalvala, Nergis
2016-05-01
In February 2016, scientists announced the first ever detection of gravitational waves from colliding black holes, launching a new era of gravitational wave astronomy and unprecedented tests of Einstein's theory of general relativity. I will describe the science and technology, and also the human story, behind the long quest that led to this discovery. Bio: Nergis Mavalvala is Professor of Physics at the Massachusetts Institute of Technology (MIT). Her research links the world of quantum mechanics, usually apparent only at the atomic scale, with gravitational waves, arising from some of the most powerful, yet elusive, forces in the cosmos. In 2016, she was part of the team that announced the first detection of gravitational waves from colliding black holes. She received a B.A. from Wellesley College in 1990 and a Ph.D. from MIT in 1997. She was a postdoctoral fellow and research scientist at the California Institute of Technology between 1997 and 2002. Since 2002, she has been on the Physics faculty at MIT, and was named a MacArthur Fellow in 2010. She is a Fellow of the American Physical Society and the Optical Society of America.
Gravitational wave detection using atom interferometry
NASA Astrophysics Data System (ADS)
Hogan, Jason
2016-05-01
The advent of gravitational wave astronomy promises to provide a new window into the universe. Low frequency gravitational waves below 10 Hz are expected to offer rich science opportunities both in astrophysics and cosmology, complementary to signals in LIGO's band. Detector designs based on atom interferometry have a number of advantages over traditional approaches in this band, including the possibility of substantially reduced antenna baseline length in space and high isolation from seismic noise for a terrestrial detector. In particular, atom interferometry based on the clock transition in group II atoms offers tantalizing new possibilities. Such a design is expected to be highly immune to laser frequency noise because the signal arises strictly from the light propagation time between two ensembles of atoms. This would allow for a gravitational wave detector with a single linear baseline, potentially offering advantages in cost and design flexibility. In support of these proposals, recent progress in long baseline atom interferometry in a 10-meter drop tower has enabled observation of matter wave interference with atomic wavepacket separations exceeding 50 cm and interferometer durations of more than 2 seconds. This approach can provide ground-based proof-of-concept demonstrations of many of the technical requirements of both terrestrial and satellite gravitational wave detectors.
Environmental Effects for Gravitational-wave Astrophysics
NASA Astrophysics Data System (ADS)
Barausse, Enrico; Cardoso, Vitor; Pani, Paolo
2015-05-01
The upcoming detection of gravitational waves by terrestrial interferometers will usher in the era of gravitational-wave astronomy. This will be particularly true when space-based detectors will come of age and measure the mass and spin of massive black holes with exquisite precision and up to very high redshifts, thus allowing for better understanding of the symbiotic evolution of black holes with galaxies, and for high-precision tests of General Relativity in strong-field, highly dynamical regimes. Such ambitious goals require that astrophysical environmental pollution of gravitational-wave signals be constrained to negligible levels, so that neither detection nor estimation of the source parameters are significantly affected. Here, we consider the main sources for space-based detectors - the inspiral, merger and ringdown of massive black-hole binaries and extreme mass-ratio inspirals - and account for various effects on their gravitational waveforms, including electromagnetic fields, cosmological evolution, accretion disks, dark matter, “firewalls” and possible deviations from General Relativity. We discover that the black-hole quasinormal modes are sharply different in the presence of matter, but the ringdown signal observed by interferometers is typically unaffected. The effect of accretion disks and dark matter depends critically on their geometry and density profile, but is negligible for most sources, except for few special extreme mass-ratio inspirals. Electromagnetic fields and cosmological effects are always negligible. We finally explore the implications of our findings for proposed tests of General Relativity with gravitational waves, and conclude that environmental effects will not prevent the development of precision gravitational-wave astronomy.
Outlook for Detecting Gravitational Waves with Pulsars
NASA Astrophysics Data System (ADS)
Kohler, Susanna
2016-04-01
Though the recent discovery of GW150914 is a thrilling success in the field of gravitational-wave astronomy, LIGO is only one tool the scientific community is using to hunt for these elusive signals. After 10 years of unsuccessful searching, how likely is it that pulsar-timing-array projects will make their own first detection soon?Frequency ranges for gravitational waves produced by different astrophysical sources. Pulsar timing arrays such as the EPTA and IPTA are used to detect low-frequency gravitational waves generated by the stochastic background and supermassive black hole binaries. [Christopher Moore, Robert Cole and Christopher Berry]Supermassive BackgroundGround-based laser interferometers like LIGO are ideal for probing ripples in space-time caused by the merger of stellar-mass black holes; these mergers cause chirps in the frequency range of tens to thousands of hertz. But how do we pick up the extremely low-frequency, nanohertz background signal caused by the orbits of pairs of supermassive black holes? For that, we need pulsar timing arrays.Pulsar timing arrays are sets of pulsars whose signals are analyzed to look for correlations in the pulse arrival time. As the space-time between us and a pulsar is stretched and then compressed by a passing gravitational wave, the pulsars pulses should arrive a little late and then a little early. Comparing these timing residuals in an array of pulsars could theoretically allow for the detection of the gravitational waves causing them.Globally, there are currently four pulsar timing array projects actively searching for this signal, with a fifth planned for the future. Now a team of scientists led by Stephen Taylor (NASA-JPL/Caltech) has estimated the likelihood that these projects will successfully detect gravitational waves in the future.Probability for SuccessExpected detection probability of the gravitational-wave background as a function of observing time, for five different pulsar timing arrays. Optimistic
Discriminating between a stochastic gravitational wave background and instrument noise
Adams, Matthew R.; Cornish, Neil J.
2010-07-15
The detection of a stochastic background of gravitational waves could significantly impact our understanding of the physical processes that shaped the early Universe. The challenge lies in separating the cosmological signal from other stochastic processes such as instrument noise and astrophysical foregrounds. One approach is to build two or more detectors and cross correlate their output, thereby enhancing the common gravitational wave signal relative to the uncorrelated instrument noise. When only one detector is available, as will likely be the case with the Laser Interferometer Space Antenna (LISA), alternative analysis techniques must be developed. Here we show that models of the noise and signal transfer functions can be used to tease apart the gravitational and instrument noise contributions. We discuss the role of gravitational wave insensitive ''null channels'' formed from particular combinations of the time delay interferometry, and derive a new combination that maintains this insensitivity for unequal arm-length detectors. We show that, in the absence of astrophysical foregrounds, LISA could detect signals with energy densities as low as {Omega}{sub gw}=6x10{sup -13} with just one month of data. We describe an end-to-end Bayesian analysis pipeline that is able to search for, characterize and assign confidence levels for the detection of a stochastic gravitational wave background, and demonstrate the effectiveness of this approach using simulated data from the third round of Mock LISA Data Challenges.
Gravitational waves in ghost free bimetric gravity
Mohseni, Morteza
2012-11-01
We obtain a set of exact gravitational wave solutions for the ghost free bimetric theory of gravity. With a flat reference metric, the theory admits the vacuum Brinkmann plane wave solution for suitable choices of the coefficients of different terms in the interaction potential. An exact gravitational wave solution corresponding to a massive scalar mode is also admitted for arbitrary choice of the coefficients with the reference metric being proportional to the spacetime metric. The proportionality factor and the speed of the wave are calculated in terms of the parameters of the theory. We also show that a F(R) extension of the theory admits similar solutions but in general is plagued with ghost instabilities.
Physical optics in a uniform gravitational field
NASA Astrophysics Data System (ADS)
Hacyan, Shahen
2012-01-01
The motion of a (quasi-)plane wave in a uniform gravitational field is studied. It is shown that the energy of an elliptically polarized wave does not propagate along a geodesic, but in a direction that is rotated with respect to the gravitational force. The similarity with the walk-off effect in anisotropic crystals or the optical Magnus effect in inhomogeneous media is pointed out.
Space Based Gravitational Wave Observatories (SGOs)
NASA Technical Reports Server (NTRS)
Livas, Jeff
2014-01-01
Space-based Gravitational-wave Observatories (SGOs) will enable the systematic study of the frequency band from 0.0001 - 1 Hz of gravitational waves, where a rich array of astrophysical sources is expected. ESA has selected The Gravitational Universe as the science theme for the L3 mission opportunity with a nominal launch date in 2034. This will be at a minimum 15 years after ground-based detectors and pulsar timing arrays announce their first detections and at least 18 years after the LISA Pathfinder Mission will have demonstrated key technologies in a dedicated space mission. It is therefore important to develop mission concepts that can take advantage of the momentum in the field and the investment in both technology development and a precision measurement community on a more near-term timescale than the L3 opportunity. This talk will discuss a mission concept based on the LISA baseline that resulted from a recent mission architecture study.
Bayesian analysis on gravitational waves and exoplanets
NASA Astrophysics Data System (ADS)
Deng, Xihao
Attempts to detect gravitational waves using a pulsar timing array (PTA), i.e., a collection of pulsars in our Galaxy, have become more organized over the last several years. PTAs act to detect gravitational waves generated from very distant sources by observing the small and correlated effect the waves have on pulse arrival times at the Earth. In this thesis, I present advanced Bayesian analysis methods that can be used to search for gravitational waves in pulsar timing data. These methods were also applied to analyze a set of radial velocity (RV) data collected by the Hobby- Eberly Telescope on observing a K0 giant star. They confirmed the presence of two Jupiter mass planets around a K0 giant star and also characterized the stellar p-mode oscillation. The first part of the thesis investigates the effect of wavefront curvature on a pulsar's response to a gravitational wave. In it we show that we can assume the gravitational wave phasefront is planar across the array only if the source luminosity distance " 2piL2/lambda, where L is the pulsar distance to the Earth (˜ kpc) and lambda is the radiation wavelength (˜ pc) in the PTA waveband. Correspondingly, for a point gravitational wave source closer than ˜ 100 Mpc, we should take into account the effect of wavefront curvature across the pulsar-Earth line of sight, which depends on the luminosity distance to the source, when evaluating the pulsar timing response. As a consequence, if a PTA can detect a gravitational wave from a source closer than ˜ 100 Mpc, the effects of wavefront curvature on the response allows us to determine the source luminosity distance. The second and third parts of the thesis propose a new analysis method based on Bayesian nonparametric regression to search for gravitational wave bursts and a gravitational wave background in PTA data. Unlike the conventional Bayesian analysis that introduces a signal model with a fixed number of parameters, Bayesian nonparametric regression sets
Gravitational wave astronomy using spaceborne detectors
NASA Astrophysics Data System (ADS)
Rubbo, Louis Joseph, IV
This dissertation explores the use of spaceborne gravitational wave detectors as observatories for studying sources of gravitational radiation. The next decade will see the launch of the first space-based gravitational wave detector. Planning for several follow on missions is already underway. Before these observatories are constructed, extensive studies into their responses, expected output, and data analysis techniques must be completed. In this dissertation these issues are addressed using the proposed Laser Interferometer Space Antenna as an exemplary model. The first original work presented here is a complete description of the response of a spaceborne detector to arbitrary gravitational wave signals. Previous analyses worked either in the static or low frequency limits. Part of this investigation is a coordinate free derivation of the response of a general detector valid for all frequencies and for arbitrary motion. Following directly from this result is The LISA Simulator, a virtual model of the LISA detector, in addition to an adiabatic approximation that extends the low frequency limit by two decades in the frequency domain. Unlike most electromagnetic telescopes, gravitational wave observatories do not return an image of a particular source. Instead they return a set of time series. Encoded within these time series are all of the sources whose gravitational radiation passes through the detector during its observational run. The second original work presented here is the extraction of multiple monochromatic, binary sources using data from multiple time series. For binaries isolated in frequency space and with a large signal to noise ratio, it is shown that these sources can be removed to a level that is below the local effective noise. A concern for the LISA mission is the large number of gravitational wave sources located within the Milky Way galaxy. The superposition of these sources will form a confusion limited background in the output of the detector
Searching for gravitational waves from neutron stars
NASA Astrophysics Data System (ADS)
Idrisy, Ashikuzzaman
generate the parameter space of a GW search so as to cover the largest physical range of parameters, while keeping the search computationally feasible. Finally we discuss the time-domain solar system barycentered resampling algorithm as a way to improve to the computational cost of the analysis. In Chapter 4 we discuss a search for GWs from two supernova remnants, G65.7 and G330.2. The searches were conducted using data from the 6th science run of the LIGO detectors. Since the searches were modeled on the Cassiopeia A search paper, Abadie et. al. [Astrophys. J. 722,1504--1513, 2010], we also used the frequency and the first and second derivatives of the frequency as the parameter space of the search. There are two main differences from the previous search. The first is the use of the resampling algorithm, which sped up the calculation of the F-statistic by a factor of 3 and thus allowed for longer stretches of data to be coherently integrated. Being able to integrate more data meant that we could beat the indirect limit on GWs expected from these sources. We used a 51 day integration time for G65.7 and 24 days for G330.2. The second difference is that the analysis pipeline is now more automated. This allows for a more efficient data analysis process. We did not find a credible source of GWs and so we placed upper limits on the gravitational wave strain, ellipticity, and r-mode amplitude of the sources. The best upper-limit for the strain was 3.0 x 10 -25, for ellipticity it was 7.0 x 10-6 and for r-mode amplitude it was 2.2 x 10-4 .
Search for Gravitational Wave Trains with the Spacecraft Ulysses
NASA Technical Reports Server (NTRS)
Bertotti, B.; Ambrosini, R.; Armstrong, J.; Asmar, S.; Comoretto, G.; Giampieri, G.; Iess, L.; Koyama, Y.; Messeri, A.; Vecchio, A.; Wahlquist, H.
1994-01-01
We report on the search for periodic gravitational wave in the mHz band conducted with the spacecraft ULYSSES. Gravitational wave signals generally provide information about the distance of the source; ULYSSES' data have a.
Quantum nondemolition measurements. [by gravitational wave antennas
NASA Technical Reports Server (NTRS)
Braginskii, V. B.; Vorontsov, Iu. I.; Thorne, K. S.
1980-01-01
The article describes new electronic techniques required for quantum nondemolition measurements and the theory underlying them. Consideration is given to resonant-bar gravitational-wave antennas. Position measurements are discussed along with energy measurements and back-action-evading measurements. Thermal noise in oscillators and amplifiers is outlined. Prospects for stroboscopic measurements are emphasized.
The Dawn of Gravitational-Wave Astrophysics
NASA Astrophysics Data System (ADS)
Kalogera, Vassiliki; LIGO - Virgo Collaborations
2016-06-01
With the detection of GW150914 and its identification as the binary merger of two heavy black holes LIGO has launched the era of gravitational-wave astrophysics. I will review what this implies for our understanding of binary compact object formation and how we can use it to constrain current models.
Ground-based gravitational-wave detectors
NASA Astrophysics Data System (ADS)
Kuroda, Kazuaki
2015-01-01
Gravitational wave is predicted by Einstein’s general relativity, which conveys the information of source objects in the universe. The detection of the gravitational wave is the direct test of the theory and will be used as new tool to investigate dynamical nature of the universe. However, the effect of the gravitational wave is too tiny to be easily detected. From the first attempt utilizing resonant antenna in the 1960s, efforts of improving antenna sensitivity were continued by applying cryogenic techniques until approaching the quantum limit of sensitivity. However, by the year 2000, resonant antenna had given the way to interferometers. Large projects involving interferometers started in the 1990s, and achieved successful operations by 2010 with an accumulated extensive number of technical inventions and improvements. In this memorial year 2015, we enter the new phase of gravitational-wave detection by the forthcoming operation of the second-generation interferometers. The main focus in this paper is on how advanced techniques have been developed step by step according to scaling the arm length of the interferometer up and the history of fighting against technical noise, thermal noise, and quantum noise is presented along with the current projects, LIGO, Virgo, GEO-HF and KAGRA.
Gravitational wave detector with cosmological reach
NASA Astrophysics Data System (ADS)
Dwyer, Sheila; Sigg, Daniel; Ballmer, Stefan W.; Barsotti, Lisa; Mavalvala, Nergis; Evans, Matthew
2015-04-01
Twenty years ago, construction began on the Laser Interferometer Gravitational-wave Observatory (LIGO). Advanced LIGO, with a factor of 10 better design sensitivity than Initial LIGO, will begin taking data this year, and should soon make detections a monthly occurrence. While Advanced LIGO promises to make first detections of gravitational waves from the nearby universe, an additional factor of 10 increase in sensitivity would put exciting science targets within reach by providing observations of binary black hole inspirals throughout most of the history of star formation, and high signal to noise observations of nearby events. Design studies for future detectors to date rely on significant technological advances that are futuristic and risky. In this paper we propose a different direction. We resurrect the idea of using longer arm lengths coupled with largely proven technologies. Since the major noise sources that limit gravitational wave detectors do not scale trivially with the length of the detector, we study their impact and find that 40 km arm lengths are nearly optimal, and can incorporate currently available technologies to detect gravitational wave sources at cosmological distances (z ≳7 ) .
Chiral primordial gravitational waves from a Lifshitz point.
Takahashi, Tomohiro; Soda, Jiro
2009-06-12
We study primordial gravitational waves produced during inflation in quantum gravity at a Lifshitz point proposed by Horava. Assuming power-counting renormalizability, foliation-preserving diffeomorphism invariance, and the condition of detailed balance, we show that primordial gravitational waves are circularly polarized due to parity violation. The chirality of primordial gravitational waves is a quite robust prediction of quantum gravity at a Lifshitz point which can be tested through observations of cosmic microwave background radiation and stochastic gravitational waves. PMID:19658921
Gravitational waves from spinning eccentric binaries
NASA Astrophysics Data System (ADS)
Csizmadia, Péter; Debreczeni, Gergely; Rácz, István; Vasúth, Mátyás
2012-12-01
This paper is to introduce a new software called CBwaves which provides a fast and accurate computational tool to determine the gravitational waveforms yielded by generic spinning binaries of neutron stars and/or black holes on eccentric orbits. This is done within the post-Newtonian (PN) framework by integrating the equations of motion and the spin precession equations, while the radiation field is determined by a simultaneous evaluation of the analytic waveforms. In applying CBwaves various physically interesting scenarios have been investigated. In particular, we have studied the appropriateness of the adiabatic approximation, and justified that the energy balance relation is indeed insensitive to the specific form of the applied radiation reaction term. By studying eccentric binary systems, it is demonstrated that circular template banks are very ineffective in identifying binaries even if they possess tiny residual orbital eccentricity, thus confirming a similar result obtained by Brown and Zimmerman (2010 Phys. Rev. D 81 024007). In addition, by investigating the validity of the energy balance relation we show that, contrary to the general expectations, the PN approximation should not be applied once the PN parameter gets beyond the critical value ˜0.08 - 0.1. Finally, by studying the early phase of the gravitational waves emitted by strongly eccentric binary systems—which could be formed e.g. in various many-body interactions in the galactic halo—we have found that they possess very specific characteristics which may be used to identify these type of binary systems. This paper is dedicated to the memory of our colleague and friend Péter Csizmadia a young physicist, computer expert and one of the best Hungarian mountaineers who disappeared in China’s Sichuan near the Ren Zhong Feng peak of the Himalayas on 23 Oct. 2009. We started to develop CBwaves jointly with Péter a couple of months before he left for China.
Implications of the gravitational wave event GW150914
NASA Astrophysics Data System (ADS)
Miller, M. Coleman
2016-07-01
The era of gravitational-wave astronomy began on 14 September 2015, when the LIGO Scientific Collaboration detected the merger of two ˜30 M_⊙ black holes at a distance of {˜ }400 Mpc. This event has facilitated qualitatively new tests of gravitational theories, and has also produced exciting information about the astrophysical origin of black hole binaries. In this review we discuss the implications of this event for gravitational physics and astrophysics, as well as the expectations for future detections. In brief: (1) because the spins of the black holes could not be measured accurately and because mergers are not well calculated for modified theories of gravity, the current analysis of GW150914 does not place strong constraints on gravity variants that change only the generation of gravitational waves, but (2) it does strongly constrain alterations of the propagation of gravitational waves and alternatives to black holes. Finally, (3) many astrophysical models for the origin of heavy black hole binaries such as the GW150914 system are in play, but a reasonably robust conclusion that was reached even prior to the detection is that the environment of such systems needs to have a relatively low abundance of elements heavier than helium.
Implications of the gravitational wave event GW150914
NASA Astrophysics Data System (ADS)
Miller, M. Coleman
2016-07-01
The era of gravitational-wave astronomy began on 14 September 2015, when the LIGO Scientific Collaboration detected the merger of two {˜ }30 M_⊙ black holes at a distance of {˜ }400 Mpc. This event has facilitated qualitatively new tests of gravitational theories, and has also produced exciting information about the astrophysical origin of black hole binaries. In this review we discuss the implications of this event for gravitational physics and astrophysics, as well as the expectations for future detections. In brief: (1) because the spins of the black holes could not be measured accurately and because mergers are not well calculated for modified theories of gravity, the current analysis of GW150914 does not place strong constraints on gravity variants that change only the generation of gravitational waves, but (2) it does strongly constrain alterations of the propagation of gravitational waves and alternatives to black holes. Finally, (3) many astrophysical models for the origin of heavy black hole binaries such as the GW150914 system are in play, but a reasonably robust conclusion that was reached even prior to the detection is that the environment of such systems needs to have a relatively low abundance of elements heavier than helium.
Plane gravitational waves in real connection variables
Hinterleitner, Franz; Major, Seth
2011-02-15
We investigate using plane-fronted gravitational wave space-times as model systems to study loop quantization techniques and dispersion relations. In this classical analysis we start with planar symmetric space-times in the real connection formulation. We reduce via Dirac constraint analysis to a final form with one canonical pair and one constraint, equivalent to the metric and Einstein equations of plane-fronted-with-parallel-rays waves. Because of the symmetries and use of special coordinates, general covariance is broken. However, this allows us to simply express the constraints of the consistent system. A recursive construction of Dirac brackets results in nonlocal brackets, analogous to those of self-dual fields, for the triad variables. Not surprisingly, this classical analysis produces no evidence for dispersion, i.e. a variable propagation speed of gravitational plane-fronted-with-parallel-rays waves.
Spherical resonant-mass gravitational wave detectors
NASA Astrophysics Data System (ADS)
Zhou, Carl Z.; Michelson, Peter F.
1995-03-01
A spherical gravitational wave antenna is a very promising detector for gravitational wave astronomy because it has a large cross section, isotropic sky coverage, and can provide the capability of determining the wave direction. In this paper we discuss several aspects of spherical detectors, including the eigenfunctions and eigenfrequencies of the normal modes of an elastic sphere, the energy cross section, and the response functions that are used to obtain the noise-free solution to the inverse problem. Using the maximum likelihood estimation method the inverse problem in the presence of noise is solved. We also determine the false-alarm probability and the detection probability for a network of spherical detectors and estimate the detectable event rates for supernova collapses and binary coalescences.
BOOK REVIEW: Gravitational Waves, Volume 1: Theory and Experiments
NASA Astrophysics Data System (ADS)
Poisson, Eric
2008-10-01
discussion is helpful, as it clarifies some of the puzzling aspects of general covariance. Next the treatment becomes more sophisticated: the waves are allowed to propagate in an arbitrary background spacetime, and the energy momentum carried by the wave is identified by the second-order perturbation of the Einstein tensor. In chapter 2 the waves are given a field-theoretic foundation that is less familiar (but refreshing) to a relativist, but would appeal to a practitioner of effective field theories. In an interesting section of chapter 2, the author gives a mass to the (classical) graviton and explores the physical consequences of this proposal. In chapter 3 the author returns to the standard linearized theory and develops the multipolar expansion of the gravitational-wave field in the context of slowly-moving sources; at leading order he obtains the famous quadrupole formula. His treatment is very detailed, and it includes a complete account of symmetric-tracefree tensors and tensorial spherical harmonics. It is, however, necessarily limited to sources with negligible internal gravity. Unfortunately (and this is a familiar complaint of relativists) the author omits to warn the reader of this important limitation. In fact, the chapter opens with a statement of the virial theorem of Newtonian gravity, which may well mislead the reader to believe that the linearized theory can be applied to a system bound by gravitational forces. This misconception is confirmed when, in chapter 4, the author applies the quadrupole formula to gravitationally-bound systems such as an inspiraling compact binary, a rigidly rotating body, and a mass falling toward a black hole. This said, the presentation of these main sources of gravitational waves is otherwise irreproachable, and a wealth of useful information is presented in a clear and lucid manner. For example, the discussion of inspiraling compact binaries includes a derivation of the orbital evolution of circular and eccentric orbits
Gravitational waves from an early matter era
Assadullahi, Hooshyar; Wands, David
2009-04-15
We investigate the generation of gravitational waves due to the gravitational instability of primordial density perturbations in an early matter-dominated era which could be detectable by experiments such as laser interferometer gravitational wave observatory (LIGO) and laser interferometer space antenna (LISA). We use relativistic perturbation theory to give analytic estimates of the tensor perturbations generated at second order by linear density perturbations. We find that large enhancement factors with respect to the naive second-order estimate are possible due to the growth of density perturbations on sub-Hubble scales. However very large enhancement factors coincide with a breakdown of linear theory for density perturbations on small scales. To produce a primordial gravitational-wave background that would be detectable with LIGO or LISA from density perturbations in the linear regime requires primordial comoving curvature perturbations on small scales of order 0.02 for advanced LIGO or 0.005 for LISA; otherwise numerical calculations of the nonlinear evolution on sub-Hubble scales are required.
Testing gravity with gravitational wave source counts
NASA Astrophysics Data System (ADS)
Calabrese, Erminia; Battaglia, Nicholas; Spergel, David N.
2016-08-01
We show that the gravitational wave source counts distribution can test how gravitational radiation propagates on cosmological scales. This test does not require obtaining redshifts for the sources. If the signal-to-noise ratio (ρ) from a gravitational wave source is proportional to the strain then it falls as {R}-1, thus we expect the source counts to follow {{d}}{N}/{{d}}ρ \\propto {ρ }-4. However, if gravitational waves decay as they propagate or propagate into other dimensions, then there can be deviations from this generic prediction. We consider the possibility that the strain falls as {R}-γ , where γ =1 recovers the expected predictions in a Euclidean uniformly-filled Universe, and forecast the sensitivity of future observations to deviations from standard General Relativity. We first consider the case of few objects, seven sources, with a signal-to-noise from 8 to 24, and impose a lower limit on γ, finding γ \\gt 0.33 at 95% confidence level. The distribution of our simulated sample is very consistent with the distribution of the trigger events reported by Advanced LIGO. Future measurements will improve these constraints: with 100 events, we estimate that γ can be measured with an uncertainty of 15%. We generalize the formalism to account for a range of chirp masses and the possibility that the signal falls as {exp}(-R/{R}0)/{R}γ .
New window into stochastic gravitational wave background.
Rotti, Aditya; Souradeep, Tarun
2012-11-30
A stochastic gravitational wave background (SGWB) would gravitationally lens the cosmic microwave background (CMB) photons. We correct the results provided in existing literature for modifications to the CMB polarization power spectra due to lensing by gravitational waves. Weak lensing by gravitational waves distorts all four CMB power spectra; however, its effect is most striking in the mixing of power between the E mode and B mode of CMB polarization. This suggests the possibility of using measurements of the CMB angular power spectra to constrain the energy density (Ω(GW)) of the SGWB. Using current data sets (QUAD, WMAP, and ACT), we find that the most stringent constraints on the present Ω(GW) come from measurements of the angular power spectra of CMB temperature anisotropies. In the near future, more stringent bounds on Ω(GW) can be expected with improved upper limits on the B modes of CMB polarization. Any detection of B modes of CMB polarization above the expected signal from large scale structure lensing could be a signal for a SGWB. PMID:23368112
Standing gravitational waves from domain walls
Gogberashvili, Merab; Myrzakul, Shynaray; Singleton, Douglas
2009-07-15
We construct a plane symmetric, standing gravitational wave for a domain wall plus a massless scalar field. The scalar field can be associated with a fluid which has the properties of 'stiff' matter, i.e., matter in which the speed of sound equals the speed of light. Although domain walls are observationally ruled out in the present era, the solution has interesting features which might shed light on the character of exact nonlinear wave solutions to Einstein's equations. Additionally this solution may act as a template for higher dimensional 'brane-world' model standing waves.
Superconducting Antenna Concept for Gravitational Waves
NASA Astrophysics Data System (ADS)
Gulian, A.; Foreman, J.; Nikoghosyan, V.; Nussinov, S.; Sica, L.; Tollaksen, J.
The most advanced contemporary efforts and concepts for registering gravitational waves are focused on measuring tiny deviations in large arm (kilometers in case of LIGO and thousands of kilometers in case of LISA) interferometers via photons. In this report we discuss a concept for the detection of gravitational waves using an antenna comprised of superconducting electrons (Cooper pairs) moving in an ionic lattice. The major challenge in this approach is that the tidal action of the gravitational waves is extremely weak compared with electromagnetic forces. Any motion caused by gravitational waves, which violates charge neutrality, will be impeded by Coulomb forces acting on the charge carriers (Coulomb blockade) in metals, as well as in superconductors. We discuss a design, which avoids the effects of Coulomb blockade. It exploits two different superconducting materials used in a form of thin wires -"spaghetti." The spaghetti will have a diameter comparable to the London penetration depth, and length of about 1-10 meters. To achieve competitive sensitivity, the antenna would require billions of spaghettis, which calls for a challenging manufacturing technology. If successfully materialized, the response of the antenna to the known highly periodic sources of gravitational radiation, such as the Pulsar in Crab Nebula will result in an output current, detectable by superconducting electronics. The antenna will require deep (0.3K) cryogenic cooling and magnetic shielding. This design may be a viable successor to LISA and LIGO concepts, having the prospect of higher sensitivity, much smaller size and directional selectivity. This concept of compact antenna may benefit also terrestrial gradiometry.
Seto, Naoki
2009-11-15
Gravitational waves (GWs) from cosmological double neutron star binaries (NS+NS) can be significantly demagnified by the strong gravitational lensing effect, and the proposed future missions such as the Big Bang Observer or Deci-hertz Interferometer Gravitational Wave Observatory might miss some of the demagnified GW signals below a detection threshold. The undetectable binaries would form a GW foreground, which might hamper detection of a very weak primordial GW signal. We discuss the outlook of this potential problem, using a simple model based on the singular isothermal sphere lens profile. Fortunately, it is expected that, for a presumable merger rate of NS+NSs, the residual foreground would be below the detection limit {omega}{sub GW,lim}{approx}10{sup -16} realized with the Big Bang Observer/Deci-hertz Interferometer Gravitational Wave Observatory by correlation analysis.
Articulated Multimedia Physics, Lesson 9, Universal Gravitation.
ERIC Educational Resources Information Center
New York Inst. of Tech., Old Westbury.
As the ninth lesson of the Articulated Multimedia Physics Course, instructional materials relating to universal gravitation are presented in this study guide. The subject is concerned with the quantitative meaning of the law of universal gravitation and its applications in astronomy. The content is arranged in scrambled form, and the use of matrix…
Gravitational waves: Perspectives of detection
NASA Astrophysics Data System (ADS)
Cerdonio, Massimo
2015-01-01
With Giovanni Losurdo, the PI of Advanced Virgo, we recently dwelled on this subject in an invited review paper [#!ncc10890bib1!#]. Here I first give a short introduction by answering in brief to a few basic and relevant questions, which I was often asked by colleagues not specifically working on gravitation. Then I highlight the main considerations discussed in [#!ncc10890bib1!#], in a sort of guide for the reader, where more details and an extensive reference list can be found. For more complete info, I call the attention to a number of beautiful pictures, kindly provided by my colleagues, which I put on the IFAE website, but are not given here nor in [#!ncc10890bib1!#]. After publication of [#!ncc10890bib1!#], a few relevant developments occurred, especially in the long-term planning of experiments, on which I report here. To update the references would have resulted in adding some sort of ten percent more than those in [#!ncc10890bib1!#], so I have added only a few, which I rate most recent and particularly relevant to the relative issue.
PREFACE: 8th Edoardo Amaldi Conference on Gravitational Waves
NASA Astrophysics Data System (ADS)
Marka, Zsuzsa; Marka, Szabolcs
2010-04-01
multimessenger approaches to gravitational wave detection also received special attention at the meeting. For the first time in the history of Amaldi conferences, plenary and contributed sessions were held to transfer ideas and experience gained with gravitational wave science inspired education and outreach projects. Additionally, Columbia University faculties working in frontier fields, which currently may not have direct connection to the field of gravitational wave science, gave enthralling presentations in the form of a 'wake-up' lecture series. The meeting also facilitated the exchange of scientific results and new ideas among all members of gravitational wave experiment collaborations and the gravitational wave theory community. Additionally, future directions in gravitational wave detection were discussed in a special session dedicated to the Gravitational Wave International Committee Roadmap. A highly entertaining and inspiring public talk titled "Songs from Space: Black Holes and the Big Bang in Audio" was given by Janna Levin and it attracted over 300 young and old science enthusiasts from and around New York City. This special issue of Classical and Quantum Gravity (Volume 27, Number 8, 2010) is published as the proceedings of Amaldi8. It contains the overview articles by invited plenary speakers, and some of the highlights of the meeting as selected by session chairs and organizers. Other Amaldi8 talks and posters appear in the refereed issue of the electronic Journal of Physics: Conference Series. This issue of CQG and the JPCS issue are electronically linked. The conference organizers gratefully acknowledge the financial support of Columbia University in the City of New York, the International Union of Pure and Applied Physics and the United States National Science Foundation. We would like to thank the Gravitational Wave International Committee for the scientific oversight, the Local Organizing Committee for the program selection, and the session chairs for the
Gravitational wave burst signal from core collapse of rotating stars
Dimmelmeier, Harald; Ott, Christian D.; Marek, Andreas; Janka, H.-Thomas
2008-09-15
We present results from detailed general relativistic simulations of stellar core collapse to a proto-neutron star, using two different microphysical nonzero-temperature nuclear equations of state as well as an approximate description of deleptonization during the collapse phase. Investigating a wide variety of rotation rates and profiles as well as masses of the progenitor stars and both equations of state, we confirm in this very general setup the recent finding that a generic gravitational wave burst signal is associated with core bounce, already known as type I in the literature. The previously suggested type II (or 'multiple-bounce') waveform morphology does not occur. Despite this reduction to a single waveform type, we demonstrate that it is still possible to constrain the progenitor and postbounce rotation based on a combination of the maximum signal amplitude and the peak frequency of the emitted gravitational wave burst. Our models include to sufficient accuracy the currently known necessary physics for the collapse and bounce phase of core-collapse supernovae, yielding accurate and reliable gravitational wave signal templates for gravitational wave data analysis. In addition, we assess the possibility of nonaxisymmetric instabilities in rotating nascent proto-neutron stars. We find strong evidence that in an iron core-collapse event the postbounce core cannot reach sufficiently rapid rotation to become subject to a classical bar-mode instability. However, many of our postbounce core models exhibit sufficiently rapid and differential rotation to become subject to the recently discovered dynamical instability at low rotation rates.
Gravitational wave searches using the DSN (Deep Space Network)
NASA Technical Reports Server (NTRS)
Nelson, S. J.; Armstrong, J. W.
1988-01-01
The Deep Space Network Doppler spacecraft link is currently the only method available for broadband gravitational wave searches in the 0.01 to 0.001 Hz frequency range. The DSN's role in the worldwide search for gravitational waves is described by first summarizing from the literature current theoretical estimates of gravitational wave strengths and time scales from various astrophysical sources. Current and future detection schemes for ground based and space based detectors are then discussed. Past, present, and future planned or proposed gravitational wave experiments using DSN Doppler tracking are described. Lastly, some major technical challenges to improve gravitational wave sensitivities using the DSN are discussed.
Breaking a dark degeneracy with gravitational waves
NASA Astrophysics Data System (ADS)
Lombriser, Lucas; Taylor, Andy
2016-03-01
We identify a scalar-tensor model embedded in the Horndeski action whose cosmological background and linear scalar fluctuations are degenerate with the concordance cosmology. The model admits a self-accelerated background expansion at late times that is stable against perturbations with a sound speed attributed to the new field that is equal to the speed of light. While degenerate in scalar fluctuations, self-acceleration of the model implies a present cosmological tensor mode propagation at lesssim95 % of the speed of light with a damping of the wave amplitude that is gtrsim5 % less efficient than in general relativity. We show that these discrepancies are endemic to self-accelerated Horndeski theories with degenerate large-scale structure and are tested with measurements of gravitational waves emitted by events at cosmological distances. Hence, gravitational-wave cosmology breaks the dark degeneracy in observations of the large-scale structure between two fundamentally different explanations of cosmic acceleration—a cosmological constant and a scalar-tensor modification of gravity. The gravitational wave event GW150914 recently detected with the aLIGO instruments and its potential association with a weak short gamma-ray burst observed with the Fermi GBM experiment may have provided this crucial measurement.
Simulating Responses of Gravitational-Wave Instrumentation
NASA Technical Reports Server (NTRS)
Armstrong, John; Edlund, Jeffrey; Vallisneri. Michele
2006-01-01
Synthetic LISA is a computer program for simulating the responses of the instrumentation of the NASA/ESA Laser Interferometer Space Antenna (LISA) mission, the purpose of which is to detect and study gravitational waves. Synthetic LISA generates synthetic time series of the LISA fundamental noises, as filtered through all the time-delay-interferometry (TDI) observables. (TDI is a method of canceling phase noise in temporally varying unequal-arm interferometers.) Synthetic LISA provides a streamlined module to compute the TDI responses to gravitational waves, according to a full model of TDI (including the motion of the LISA array and the temporal and directional dependence of the arm lengths). Synthetic LISA is written in the C++ programming language as a modular package that accommodates the addition of code for specific gravitational wave sources or for new noise models. In addition, time series for waves and noises can be easily loaded from disk storage or electronic memory. The package includes a Python-language interface for easy, interactive steering and scripting. Through Python, Synthetic LISA can read and write data files in Flexible Image Transport System (FITS), which is a commonly used astronomical data format.
Pseudospectral method for gravitational wave collapse
NASA Astrophysics Data System (ADS)
Hilditch, David; Weyhausen, Andreas; Brügmann, Bernd
2016-03-01
We present a new pseudospectral code, bamps, for numerical relativity written with the evolution of collapsing gravitational waves in mind. We employ the first-order generalized harmonic gauge formulation. The relevant theory is reviewed, and the numerical method is critically examined and specialized for the task at hand. In particular, we investigate formulation parameters—gauge- and constraint-preserving boundary conditions well suited to nonvanishing gauge source functions. Different types of axisymmetric twist-free moment-of-time-symmetry gravitational wave initial data are discussed. A treatment of the axisymmetric apparent horizon condition is presented with careful attention to regularity on axis. Our apparent horizon finder is then evaluated in a number of test cases. Moving on to evolutions, we investigate modifications to the generalized harmonic gauge constraint damping scheme to improve conservation in the strong-field regime. We demonstrate strong-scaling of our pseudospectral penalty code. We employ the Cartoon method to efficiently evolve axisymmetric data in our 3 +1 -dimensional code. We perform test evolutions of the Schwarzschild spacetime perturbed by gravitational waves and by gauge pulses, both to demonstrate the use of our black-hole excision scheme and for comparison with earlier results. Finally, numerical evolutions of supercritical Brill waves are presented to demonstrate durability of the excision scheme for the dynamical formation of a black hole.
CMB μ distortion from primordial gravitational waves
Ota, Atsuhisa; Yamaguchi, Masahide; Takahashi, Tomo; Tashiro, Hiroyuki E-mail: tomot@cc.saga-u.ac.jp E-mail: gucci@phys.titech.ac.jp
2014-10-01
We propose a new mechanism of generating the μ distortion in cosmic microwave background (CMB) originated from primordial gravitational waves. Such μ distortion is generated by the damping of the temperature anisotropies through the Thomson scattering, even on scales larger than that of Silk damping. This mechanism is in sharp contrast with that from the primordial curvature (scalar) perturbations, in which the temperature anisotropies mainly decay by Silk damping effects. We estimate the size of the μ distortion from the new mechanism, which can be used to constrain the amplitude of primordial gravitational waves on smaller scales independently from the CMB anisotropies, giving more wide-range constraint on their spectral index by combining the amplitude from the CMB anisotropies.
Gravitational wave memory in an expanding universe
NASA Astrophysics Data System (ADS)
Tolish, Alexander; Wald, Robert
2016-03-01
We investigate the gravitational wave memory effect in an expanding FLRW spacetime. We find that if the gravitational field is decomposed into gauge-invariant scalar, vector, and tensor modes after the fashion of Bardeen, only the tensor mode gives rise to memory, and this memory can be calculated using the retarded Green's function associated with the tensor wave equation. If locally similar radiation source events occur on flat and FLRW backgrounds, we find that the resulting memories will differ only by a redshift factor, and we explore whether or not this factor depends on the expansion history of the FLRW universe. We compare our results to related work by Bieri, Garfinkle, and Yau.
Gravitational waves from the first stars
Sandick, Pearl; Olive, Keith A.; Daigne, Frederic; Vangioni, Elisabeth
2006-05-15
We consider the stochastic background of gravitational waves produced by an early generation of Population III stars coupled with a normal mode of star formation at lower redshift. The computation is performed in the framework of hierarchical structure formation and is based on cosmic star formation histories constrained to reproduce the observed star formation rate at redshift z < or approx. 6, the observed chemical abundances in damped Lyman alpha absorbers and in the intergalactic medium, and to allow for an early reionization of the Universe at z{approx}11 as indicated by the third year results released by WMAP. We find that the normal mode of star formation produces a gravitational wave background which peaks at 300-500 Hz and is within LIGO III sensitivity. The Population III component peaks at lower frequencies (30-100 Hz depending on the model), and could be detected by LIGO III as well as the planned BBO and DECIGO interferometers.
Gravitational Wave Experiments - Proceedings of the First Edoardo Amaldi Conference
NASA Astrophysics Data System (ADS)
Coccia, E.; Pizzella, G.; Ronga, F.
1995-07-01
Table of Contents for the full book PDF is as follows: * Foreword * Notes on Edoardo Amaldi's Life and Activity * PART I. INVITED LECTURES * Sources and Telescopes * Sources of Gravitational Radiation for Detectors of the 21st Century * Neutrino Telescopes * γ-Ray Bursts * Space Detectors * LISA — Laser Interferometer Space Antenna for Gravitational Wave Measurements * Search for Massive Coalescing Binaries with the Spacecraft ULYSSES * Interferometers * The LIGO Project: Progress and Prospects * The VIRGO Experiment: Status of the Art * GEO 600 — A 600-m Laser Interferometric Gravitational Wave Antenna * 300-m Laser Interferometer Gravitational Wave Detector (TAMA300) in Japan * Resonant Detectors * Search for Continuous Gravitational Wave from Pulsars with Resonant Detector * Operation of the ALLEGRO Detector at LSU * Preliminary Results of the New Run of Measurements with the Resonant Antenna EXPLORER * Operation of the Perth Cryogenic Resonant-Bar Gravitational Wave Detector * The NAUTILUS Experiment * Status of the AURIGA Gravitational Wave Antenna and Perspectives for the Gravitational Waves Search with Ultracryogenic Resonant Detectors * Ultralow Temperature Resonant-Mass Gravitational Radiation Detectors: Current Status of the Stanford Program * Electromechanical Transducers and Bandwidth of Resonant-Mass Gravitational-Wave Detectors * Fully Numerical Data Analysis for Resonant Gravitational Wave Detectors: Optimal Filter and Available Information * PART II. CONTRIBUTED PAPERS * Sources and Telescopes * The Local Supernova Production * Periodic Gravitational Signals from Galactic Pulsars * On a Possibility of Scalar Gravitational Wave Detection from the Binary Pulsars PSR 1913+16 * Kazan Gravitational Wave Detector “Dulkyn”: General Concept and Prospects of Construction * Hierarchical Approach to the Theory of Detection of Periodic Gravitational Radiation * Application of Gravitational Antennae for Fundamental Geophysical Problems * On Production
Physics through the 1990s: Gravitation, cosmology and cosmic-ray physics
NASA Technical Reports Server (NTRS)
1986-01-01
The volume contains recommendations for space-and ground-based programs in gravitational physics, cosmology, and cosmic-ray physics. The section on gravitation examines current and planned experimental tests of general relativity; the theory behind, and search for, gravitational waves, including sensitive laser-interferometric tests and other observations; and advances in gravitation theory (for example, incorporating quantum effects). The section on cosmology deals with the big-bang model, the standard model from elementary-particle theory, the inflationary model of the Universe. Computational needs are presented for both gravitation and cosmology. Finally, cosmic-ray physics theory (nucleosynthesis, acceleration models, high-energy physics) and experiment (ground and spaceborne detectors) are discussed.
"Spaghetti" design for gravitational wave superconducting antenna
NASA Astrophysics Data System (ADS)
Gulian, A.; Foreman, J.; Nikoghosyan, V.; Nussinov, S.; Sica, L.; Tollaksen, J.
2014-05-01
A new concept for detectors of gravitational wave radiation is discussed. Estimates suggest that strain sensitivity essentially better than that of the existing devices can be achieved in the wide frequency range. Such sensitivity could be obtained with devices about one meter long. Suggested device consists of multi-billion bimetallic superconducting wires ("spaghettis") and requires cryogenic operational temperatures (~0.3K in the case considered).
Relic gravitational waves and extended inflation
NASA Technical Reports Server (NTRS)
Turner, Michael S.; Wilczek, Frank
1990-01-01
In extended inflation, a new version of inflation where the transition from an inflationary to a radiation-dominated universe is accomplished by bubble nucleation, bubble collisions supply a potent - and potentially detectable - source of gravitational waves. The energy density in relic gravitons from bubble collisions is expected to be about 0.00005 of closure density. Their characteristic wavelength depends on the reheating temperature. If black holes are produced by bubble collisions, they will evaporate, producing shorter-wavelength gravitons.
The GEO 600 gravitational wave detector
NASA Astrophysics Data System (ADS)
Willke, B.; Aufmuth, P.; Aulbert, C.; Babak, S.; Balasubramanian, R.; Barr, B. W.; Berukoff, S.; Bose, S.; Cagnoli, G.; Casey, M. M.; Churches, D.; Clubley, D.; Colacino, C. N.; Crooks, D. R. M.; Cutler, C.; Danzmann, K.; Davies, R.; Dupuis, R.; Elliffe, E.; Fallnich, C.; Freise, A.; Goßler, S.; Grant, A.; Grote, H.; Heinzel, G.; Heptonstall, A.; Heurs, M.; Hewitson, M.; Hough, J.; Jennrich, O.; Kawabe, K.; Kötter, K.; Leonhardt, V.; Lück, H.; Malec, M.; McNamara, P. W.; McIntosh, S. A.; Mossavi, K.; Mohanty, S.; Mukherjee, S.; Nagano, S.; Newton, G. P.; Owen, B. J.; Palmer, D.; Papa, M. A.; Plissi, M. V.; Quetschke, V.; Robertson, D. I.; Robertson, N. A.; Rowan, S.; Rüdiger, A.; Sathyaprakash, B. S.; Schilling, R.; Schutz, B. F.; Senior, R.; Sintes, A. M.; Skeldon, K. D.; Sneddon, P.; Stief, F.; Strain, K. A.; Taylor, I.; Torrie, C. I.; Vecchio, A.; Ward, H.; Weiland, U.; Welling, H.; Williams, P.; Winkler, W.; Woan, G.; Zawischa, I.
2002-04-01
The GEO 600 laser interferometer with 600 m armlength is part of a worldwide network of gravitational wave detectors. Due to the use of advanced technologies like multiple pendulum suspensions with a monolithic last stage and signal recycling, the anticipated sensitivity of GEO 600 is close to the initial sensitivity of detectors with several kilometres armlength. This paper describes the subsystems of GEO 600, the status of the detector by September 2001 and the plans towards the first science run.
Kinks, extra dimensions, and gravitational waves
O'Callaghan, Eimear; Gregory, Ruth
2011-03-01
We investigate in detail the gravitational wave signal from kinks on cosmic (super)strings, including the kinematical effects from the internal extra dimensions. We find that the signal is suppressed, however, the effect is less significant that that for cusps. Combined with the greater incidence of kinks on (super)strings, it is likely that the kink signal offers the better chance for detection of cosmic (super)strings.
Gravitational Waves from Black Hole Mergers
NASA Technical Reports Server (NTRS)
Centrella, Joan
2007-01-01
The final merger of two black holes is expected to be the strongest gravitational wave source for ground-based interferometers such as LIGO, VIRGO, and GEO600, as well as the space-based interferometer LISA. Observing these sources with gravitational wave detectors requires that we know the radiation waveforms they emit. Since these mergers take place in regions of extreme gravity, we need to solve Einstein's equations of general relativity on a computer in order to calculate these waveforms. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new simulations that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, data analysis, and astrophysics.
Astrophysical calibration of gravitational-wave detectors
NASA Astrophysics Data System (ADS)
Pitkin, M.; Messenger, C.; Wright, L.
2016-03-01
We investigate a method to assess the validity of gravitational-wave detector calibration through the use of gamma-ray bursts as standard sirens. Such signals, as measured via gravitational-wave observations, provide an estimated luminosity distance that is subject to uncertainties in the calibration of the data. If a host galaxy is identified for a given source then its redshift can be combined with current knowledge of the cosmological parameters yielding the true luminosity distance. This will then allow a direct comparison with the estimated value and can validate the accuracy of the original calibration. We use simulations of individual detectable gravitational-wave signals from binary neutron star (BNS) or neutron star-black hole systems, which we assume to be found in coincidence with short gamma-ray bursts, to estimate any discrepancy in the overall scaling of the calibration for detectors in the Advanced LIGO and Advanced Virgo network. We find that the amplitude scaling of the calibration for the LIGO instruments could on average be confirmed to within ˜10 % for a BNS source within 100 Mpc. This result is largely independent of the current detector calibration method and gives an uncertainty that is competitive with that expected in the current calibration procedure. Confirmation of the calibration accuracy to within ˜20 % can be found with BNS sources out to ˜500 Mpc .
Separating Gravitational Wave Signals from Instrument Artifacts
NASA Technical Reports Server (NTRS)
Littenberg, Tyson B.; Cornish, Neil J.
2010-01-01
Central to the gravitational wave detection problem is the challenge of separating features in the data produced by astrophysical sources from features produced by the detector. Matched filtering provides an optimal solution for Gaussian noise, but in practice, transient noise excursions or "glitches" complicate the analysis. Detector diagnostics and coincidence tests can be used to veto many glitches which may otherwise be misinterpreted as gravitational wave signals. The glitches that remain can lead to long tails in the matched filter search statistics and drive up the detection threshold. Here we describe a Bayesian approach that incorporates a more realistic model for the instrument noise allowing for fluctuating noise levels that vary independently across frequency bands, and deterministic "glitch fitting" using wavelets as "glitch templates", the number of which is determined by a trans-dimensional Markov chain Monte Carlo algorithm. We demonstrate the method's effectiveness on simulated data containing low amplitude gravitational wave signals from inspiraling binary black hole systems, and simulated non-stationary and non-Gaussian noise comprised of a Gaussian component with the standard LIGO/Virgo spectrum, and injected glitches of various amplitude, prevalence, and variety. Glitch fitting allows us to detect significantly weaker signals than standard techniques.
Separating gravitational wave signals from instrument artifacts
Littenberg, Tyson B.; Cornish, Neil J.
2010-11-15
Central to the gravitational wave detection problem is the challenge of separating features in the data produced by astrophysical sources from features produced by the detector. Matched filtering provides an optimal solution for Gaussian noise, but in practice, transient noise excursions or ''glitches'' complicate the analysis. Detector diagnostics and coincidence tests can be used to veto many glitches which may otherwise be misinterpreted as gravitational wave signals. The glitches that remain can lead to long tails in the matched filter search statistics and drive up the detection threshold. Here we describe a Bayesian approach that incorporates a more realistic model for the instrument noise allowing for fluctuating noise levels that vary independently across frequency bands, and deterministic glitch fitting using wavelets as glitch templates, the number of which is determined by a transdimensional Markov chain Monte Carlo algorithm. We demonstrate the method's effectiveness on simulated data containing low amplitude gravitational wave signals from inspiraling binary black-hole systems, and simulated nonstationary and non-Gaussian noise comprised of a Gaussian component with the standard LIGO/Virgo spectrum, and injected glitches of various amplitude, prevalence, and variety. Glitch fitting allows us to detect significantly weaker signals than standard techniques.
Gravitational waves from the big bounce
Mielczarek, Jakub
2008-11-15
In this paper we investigate gravitational wave production during the big bounce phase, inspired by loop quantum cosmology. We consider the influence of the holonomy corrections to the equation for tensor modes. We show that they act like additional effective graviton mass, suppressing gravitational wave creation. However, such effects can be treated perturbatively. We investigate a simplified model without holonomy corrections to the equation for modes and find its exact analytical solution. Assuming the form for matter {rho}{proportional_to}a{sup -2} we calculate the full spectrum of the gravitational waves from the big bounce phase. The spectrum obtained decreases to zero for the low energy modes. On the basis of this observation we infer that this effect can lead to low cosmic microwave background (CMB) multipole suppression and gives a potential way for testing loop quantum cosmology models. We also consider a scenario with a post-bounce inflationary phase. The power spectrum obtained gives a qualitative explanation of the CMB spectra, including low multipole suppression.
LIGO and the Search for Gravitational Waves
Robertson, Norna A.
2006-10-16
Gravitational waves, predicted to exist by Einstein's General Theory of Relativity but as yet undetected, are expected to be emitted during violent astrophysical events such as supernovae, black hole interactions and the coalescence of compact binary systems. Their detection and study should lead to a new branch of astronomy. However the experimental challenge is formidable: ground-based detection relies on sensing displacements of order 10{sup -18} m over a frequency range of tens of hertz to a few kHz. There is currently a large international effort to commission and operate long baseline interferometric detectors including those that comprise LIGO - the Laser Interferometer Gravitational-Wave Observatory - in the USA. In this talk I will give an introduction to the topic of gravitational wave detection and in particular review the status of the LIGO project which is currently taking data at its design sensitivity. I will also look to the future to consider planned improvements in sensitivity for such detectors, focusing on Advanced LIGO, the proposed upgrade to the LIGO project.
Relic gravitational waves and extended inflation
NASA Technical Reports Server (NTRS)
Turner, Michael S.; Wilczek, Frank
1990-01-01
In extended inflation, a new version of inflation where the transition from the false-vacuum phase to a radiation-dominated Universe is accomplished by bubble nucleation and percolation, bubble collisions supply a potent-and potentially detectable-source of gravitational waves. The present energy density in relic gravity waves from bubble collisions is expected to be about 10(exp -5) of closure density-many orders of magnitude greater than that of the gravity waves produced by quantum fluctuations. Their characteristic wavelength depends upon the reheating temperature T(sub RH): lambda is approximately 10(exp 4) cm (10(exp 14) GeV/T(sub RH)). If large numbers of black holes are produced, a not implausible outcome, they will evaporate producing comparable amounts of shorter wavelength waves, lambda is approximately 10(exp -6) cm (T(sub RH)/10(exp 14) GeV).
Gravitational wave detection with the solar probe: I. Motivation
NASA Technical Reports Server (NTRS)
Thorne, K. S.
1978-01-01
Questions are posed and answered through discussion of gravitational wave detection with the Solar Probe. Discussed are: (1) what a gravitational wave is; (2) why wave detection is important; (3) what astrophysical information might be learned from these waves; (4) status of attempts to detect these waves; (5) why the Solar Probe is a special mission for detecting these waves; (6) how the Solar Probe's expected sensitivity compares with the strength of predicted gravitational waves; and (7) what gravity wave searchers will do after the Solar Probe.
Gravitational waves: Some less discussed intriguing issues
NASA Astrophysics Data System (ADS)
Sivaram, C.
2015-11-01
Attempts to detect gravitational waves is actively in progress with sophisticated devices like LIGO setup across continents. Despite being predicted almost 100 years ago, there has so far been no direct detection of these waves. In this work, we draw attention to some of the less discussed but subtle aspects arising, for example, from high orbital eccentricities, where emission near periastron could be millions of times more than that in the distant parts of the orbit. The strong field nonlinear effects close to the compact objects can substantially slow down and deflect the waves in the last (few) orbit(s) where much of the intensity is expected. Spin-orbit and other forces could be significant. There would also be plasma like resonant absorption (of kilohertz radiation) during the collapse. Recent observation of supermassive black holes at high redshift implies cluster collapse, where the gravitational wave intensity depends on very high powers of the mass. Any unambiguous claim of detection should perhaps consider several of these effects.
Gravitational waves from the electroweak phase transition
Leitao, Leonardo; Mégevand, Ariel; Sánchez, Alejandro D. E-mail: megevand@mdp.edu.ar
2012-10-01
We study the generation of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model, namely, the addition of scalar singlets, the minimal supersymmetric extension, and the addition of TeV fermions. For each model we consider the complete dynamics of the phase transition. In particular, we estimate the friction force acting on bubble walls, and we take into account the fact that they can propagate either as detonations or as deflagrations preceded by shock fronts, or they can run away. We compute the peak frequency and peak intensity of the gravitational radiation generated by bubble collisions and turbulence. We discuss the detectability by proposed spaceborne detectors. For the models we considered, runaway walls require significant fine tuning of the parameters, and the gravitational wave signal from bubble collisions is generally much weaker than that from turbulence. Although the predicted signal is in most cases rather low for the sensitivity of LISA, models with strongly coupled extra scalars reach this sensitivity for frequencies f ∼ 10{sup −4} Hz, and give intensities as high as h{sup 2}Ω{sub GW} ∼ 10{sup −8}.
Gravitational waves from the electroweak phase transition
NASA Astrophysics Data System (ADS)
Leitao, Leonardo; Mégevand, Ariel; Sánchez, Alejandro D.
2012-10-01
We study the generation of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model, namely, the addition of scalar singlets, the minimal supersymmetric extension, and the addition of TeV fermions. For each model we consider the complete dynamics of the phase transition. In particular, we estimate the friction force acting on bubble walls, and we take into account the fact that they can propagate either as detonations or as deflagrations preceded by shock fronts, or they can run away. We compute the peak frequency and peak intensity of the gravitational radiation generated by bubble collisions and turbulence. We discuss the detectability by proposed spaceborne detectors. For the models we considered, runaway walls require significant fine tuning of the parameters, and the gravitational wave signal from bubble collisions is generally much weaker than that from turbulence. Although the predicted signal is in most cases rather low for the sensitivity of LISA, models with strongly coupled extra scalars reach this sensitivity for frequencies f ~ 10-4 Hz, and give intensities as high as h2ΩGW ~ 10-8.
PREFACE: VII Mexican School on Gravitation and Mathematical Physics
NASA Astrophysics Data System (ADS)
Alcubierre Moya, Miguel; García Compeán, Héctor Hugo; Ureña López, Luis Arturo
2007-07-01
The present collection of papers was presented during the VII Mexican School on Gravitation and Mathematical Physics, which was held in Playa del Carmen, Quintana Roo, México, from 26 November to 2 December 2006. The Mexican School on Gravitation and Mathematical Physics, sponsored by the Mexican Physical Society, started in 1994 with the purpose of discussing and exchanging current ideas in gravitational physics. Each school has been devoted to a particular subject, and on previous occasions these subjects have covered topics such as supergravity, branes, black holes, the early Universe, observational cosmology, and quantum gravity. At the dawn of the XXI Century, General Relativity has finally become a standard tool in our understanding of numerous astrophysical phenomena. At the same time, the new generation of large interferometric gravitational wave detectors that are just beginning operation holds the promise of finally allowing the detection of gravitational waves and opening a new window on the Universe. However, because of the complexity of the Einstein field equations, the modelling of realistic astrophysical systems and gravitational wave sources can only be done using numerical simulations. Because of this, we have dedicated our VII School to the topic of relativistic astrophysics and numerical relativity. As in all our previous Schools, international leaders in the field were invited to give courses and plenary lectures. The school was complemented with more specialized talks presented in parallel sessions, some of which are included in these proceedings. All the contributions in this volume have been refereed, and they represent a sample of the courses, invited talks and contributed talks presented during our VII School. Our deep gratitude goes to all those who contributed to these proceedings, and to making our VII Mexican School a great success. Miguel Alcubierre Moya, Héctor Hugo García Compeán and Luis Arturo Ureña López Editors
Kuroyanagi, Sachiko; Chiba, Takeshi; Sugiyama, Naoshi
2011-02-15
We study the potential impact of detecting the inflationary gravitational wave background by the future space-based gravitational wave detectors, such as DECIGO and BBO. The signal-to-noise ratio of each experiment is calculated for chaotic/natural/hybrid inflation models by using the precise predictions of the gravitational wave spectrum based on numerical calculations. We investigate the dependence of each inflation model on the reheating temperature which influences the amplitude and shape of the spectrum, and find that the gravitational waves could be detected for chaotic/natural inflation models with high reheating temperature. From the detection of the gravitational waves, a lower bound on the reheating temperature could be obtained. The implications of this lower bound on the reheating temperature for particle physics are also discussed.
Probing the Association of Gravitational-Wave and Gamma-Ray Bursts with LIGO and Virgo
NASA Astrophysics Data System (ADS)
Cadonati, Laura
2010-02-01
Gamma Ray Bursts (GRBs), intense flashes of γ-rays routinely detected by satellite-based detectors, have been a target of gravitational wave searches since the early days of laser interferometer data acquisition. A measured correlation between GRBs and gravitational wave transients would provide not only a smoking-gun evidence for the detection of gravitational waves, but also new insights in the physics of GRB progenitors. This talk presents the results of a search for gravitational wave bursts associated with 137 GRBs detected during the fifth LIGO Science run and the first Virgo science run. We discuss the astrophysical interpretation and implication of these results for future investigations of GRBs and gravitational wave bursts. )
Modulation of a chirp gravitational wave from a compact binary due to gravitational lensing
Yamamoto, Kazuhiro
2005-05-15
A possible wave effect in the gravitational lensing phenomenon is discussed. We consider the interference of two coherent gravitational waves of slightly different frequencies from a compact binary, due to the gravitational lensing by a galaxy halo. This system shows the modulation of the wave amplitude. The lensing probability of such the phenomenon is of order 10{sup -5} for a high-z source, but it may be advantageous to the observation due to the magnification of the amplitude.
Gravitational waves from a curvaton model with blue spectrum
Kawasaki, Masahiro; Kitajima, Naoya; Yokoyama, Shuichiro E-mail: nk610@icrr.u-tokyo.ac.jp
2013-08-01
We investigate the gravitational wave background induced by the first order scalar perturbations in the curvaton models. We consider the quadratic and axion-like curvaton potential which can generate the blue-tilted power spectrum of curvature perturbations on small scales and derive the maximal amount of gravitational wave background today. We find the power spectrum of the induced gravitational wave background has a characteristic peak at the frequency corresponding to the scale reentering the horizon at the curvaton decay, in the case where the curvaton does not dominate the energy density of the Universe. We also find the enhancement of the amount of the gravitational waves in the case where the curvaton dominates the energy density of the Universe. Such induced gravitational waves would be detectable by the future space-based gravitational wave detectors or pulsar timing observations.
Doppler-cancelled response to VLF gravitational waves
NASA Technical Reports Server (NTRS)
Caporali, A.
1981-01-01
The interaction of long periodic gravitational waves with a three link microwave system known as the Doppler Cancelling System is discussed. This system, which was developed for a gravitational redshift experiment, uses one-way and two-way Doppler informatin to construct the beat signal of two reference oscillators moving with respect to each other. The geometric optics approximation is used to derive the frequency shift produced on a light signal propagating in a gravitational wave space-time. The signature left on the Doppler-cancelled beat by burst and continuous gravitational waves is analyzed. A comparison is made between the response to gravitational waves of the Doppler Cancelling System and that of a Doppler tracking system which employs two-way, round-trip radio waves. A three-fold repetition of the gravitational wave form is found to be a common feature of the response functions of both systems. These two functions otherwise exhibit interesting differences.
Gravitational Wave Search with the Clock Mission
NASA Technical Reports Server (NTRS)
Armstrong, J. W.
1997-01-01
Doppler tracking of distant spacecraft is the only method currently available to search for gravitational waves in the low-frequency (approx. 0.0001-0.1 Hz) band. In this technique the Doppler system measures the relative dimensionless velocity 2(delta)v/c = (delta)f/f(sub o) between the earth and the spacecraft as a function of time, where (delta)f is the frequency perturbation and f(sub o) is the nominal frequency of the radio link. A gravitational wave of amplitude h incident on this system causes small frequency perturbations, of order h in (delta)f/f(sub o), replicated three times in the observed record (Estabrook and Wahlquist 1975). All experiments to date and those planned for the near future involve only 'two-way' Doppler-i.e., uplink signal coherently transponded by the spacecraft with Doppler measured using a frequency standard common to the transmit and receive chains of the ground station. If, as on the proposed Clock Mission, there is an additional frequency standard on the spacecraft and a suitable earth-spacecraft radio system, some noise sources can be isolated and removed from the data (Vessot and Levine 1978). Supposing that the Clock Mission spacecraft is transferred into a suitable interplanetary orbit, I discuss here how the on-board frequency standard could be employed with an all-Ka-band radio system using the very high stability Deep Space Network station DSS 25 being instrumented for Cassini. With this configuration, the Clock Mission could search for gravitational waves at a sensitivity limited by the frequency standards, rather than plasma or tropospheric scintillation effects, whenever the sun-earth-spacecraft angle is greater than 90 degrees.
Building an International Gravitational Wave Network
NASA Astrophysics Data System (ADS)
Ballmer, Stefan; LSC; Virgo Collaboration
2007-12-01
The international network of ground-based gravitational wave detectors has reached an astrophysically interesting sensitivity and has recently completed its first extended Science run. The network consists of the three LIGO interferometers in the United States, the VIRGO interferometer in Italy, as well as the GEO600 instrument in Germany. I will review the performance of the detectors during the latest run and describe the currently limiting sources of noise, showing that it is possible to further improve the sensitivity with the ongoing upgrades.
Detecting gravitational wave bursts with Pulsar Timing
NASA Astrophysics Data System (ADS)
Cornish, Neil; Ellis, Justin
2016-03-01
The history of astronomy has shown that the Universe is full of suprises. One of the great hopes for gravitational wave astronomy is the discovery of unanticipated phenomena. To accomplish this we need to develop flexible analysis techniques that are able to detect signals with arbitrary waveform morphology. Here I will describe a multi-wavelet approach for the analysis of timing residuals from a pulsar timing array. Please schedule my talk immediately after the related talk by my co-author Justin Ellis.
Detecting Gravitational Waves using Pade Approximants
NASA Astrophysics Data System (ADS)
Porter, E. K.; Sathyaprakash, B. S.
1998-12-01
We look at the use of Pade Approximants in defining a metric tensor for the inspiral waveform template manifold. By using this method we investigate the curvature of the template manifold and the number of templates needed to carry out a realistic search for a Gravitational Wave signal. By comparing this method with the normal use of Taylor Approximant waveforms we hope to show that (a) Pade Approximants are a superior method for calculating the inspiral waveform, and (b) the number of search templates needed, and hence computing power, is reduced.
Primordial gravitational waves from the space-condensate inflation model
NASA Astrophysics Data System (ADS)
Koh, Seoktae; Lee, Bum-Hoon; Tumurtushaa, Gansukh
2016-04-01
We consider the space-condensate inflation model to study the primordial gravitational waves generated in the early Universe. We calculate the energy spectrum of gravitational waves induced by the space-condensate inflation model for the full frequency range with the assumption that the phase transition between two consecutive regimes is abrupt during the evolution of the Universe. The suppression of the energy spectrum is found in our model for the decreasing frequency of gravitational waves depending on the model parameter. To realize the suppression of the energy spectrum of the primordial gravitational waves, we study the existence of the early phase transition during inflation for the space-condensate inflation model.
Gravitational waves from self-ordering scalar fields
Fenu, Elisa; Durrer, Ruth; Figueroa, Daniel G.; García-Bellido, Juan E-mail: daniel.figueroa@uam.es E-mail: juan.garciabellido@uam.es
2009-10-01
Gravitational waves were copiously produced in the early Universe whenever the processes taking place were sufficiently violent. The spectra of several of these gravitational wave backgrounds on subhorizon scales have been extensively studied in the literature. In this paper we analyze the shape and amplitude of the gravitational wave spectrum on scales which are superhorizon at the time of production. Such gravitational waves are expected from the self ordering of randomly oriented scalar fields which can be present during a thermal phase transition or during preheating after hybrid inflation. We find that, if the gravitational wave source acts only during a small fraction of the Hubble time, the gravitational wave spectrum at frequencies lower than the expansion rate at the time of production behaves as Ω{sub GW}(f) ∝ f{sup 3} with an amplitude much too small to be observable by gravitational wave observatories like LIGO, LISA or BBO. On the other hand, if the source is active for a much longer time, until a given mode which is initially superhorizon (kη{sub *} << 1), enters the horizon, for kη ∼> 1, we find that the gravitational wave energy density is frequency independent, i.e. scale invariant. Moreover, its amplitude for a GUT scale scenario turns out to be within the range and sensitivity of BBO and marginally detectable by LIGO and LISA. This new gravitational wave background can compete with the one generated during inflation, and distinguishing both may require extra information.
Gravitational-wave stochastic background from cosmic strings.
Siemens, Xavier; Mandic, Vuk; Creighton, Jolien
2007-03-16
We consider the stochastic background of gravitational waves produced by a network of cosmic strings and assess their accessibility to current and planned gravitational wave detectors, as well as to big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and pulsar timing constraints. We find that current data from interferometric gravitational wave detectors, such as Laser Interferometer Gravitational Wave Observatory (LIGO), are sensitive to areas of parameter space of cosmic string models complementary to those accessible to pulsar, BBN, and CMB bounds. Future more sensitive LIGO runs and interferometers such as Advanced LIGO and Laser Interferometer Space Antenna (LISA) will be able to explore substantial parts of the parameter space. PMID:17501038
Thermal noise from optical coatings in gravitational wave detectors.
Harry, Gregory M; Armandula, Helena; Black, Eric; Crooks, D R M; Cagnoli, Gianpietro; Hough, Jim; Murray, Peter; Reid, Stuart; Rowan, Sheila; Sneddon, Peter; Fejer, Martin M; Route, Roger; Penn, Steven D
2006-03-01
Gravitational waves are a prediction of Einstein's general theory of relativity. These waves are created by massive objects, like neutron stars or black holes, oscillating at speeds appreciable to the speed of light. The detectable effect on the Earth of these waves is extremely small, however, creating strains of the order of 10(-21). There are a number of basic physics experiments around the world designed to detect these waves by using interferometers with very long arms, up to 4 km in length. The next-generation interferometers are currently being designed, and the thermal noise in the mirrors will set the sensitivity over much of the usable bandwidth. Thermal noise arising from mechanical loss in the optical coatings put on the mirrors will be a significant source of noise. Achieving higher sensitivity through lower mechanical loss coatings, while preserving the crucial optical and thermal properties, is an area of active research right now. PMID:16539265
Astronomers Get New Tools for Gravitational-Wave Detection
NASA Astrophysics Data System (ADS)
2010-01-01
exclaimed. "Fermi showed us where to look." "This is a huge help in our effort to use millisecond pulsars to detect gravitational waves," Ransom said. The more such pulsars scientists can find and observe over time, the more likely they are to detect gravitational waves, he explained. He said that astronomers now have barely enough millisecond pulsars to make a convincing gravitational-wave detection. "With Fermi guiding the way, though, we can change that picture quickly," Ray said. "We've just started to follow up on the objects located by Fermi, and have many more to go, with a great success rate so far," he added. Ransom, along with his colleague Mallory Roberts of Eureka Scientific, used the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) to find eight of the 17 new pulsars. The scientists announced their discoveries at the American Astronomical Society's meeting in Washington, DC. Pulsars are neutron stars -- the dense cores left after a massive star has exploded as a supernova. About as large as a medium-sized city, these neutron stars have strong magnetic fields that channel lighthouse-like beams of radio waves that sweep through space as the star rotates. When such a beam strikes the Earth, radio telescopes can detect the strong radio waves. As they age, pulsars slow their rotation rates. However, if the pulsar is part of a binary-star system and can draw in material from its companion, its rotation can be sped up. When the neutron star has been sped up to rotate hundreds of times a second, it is called a millisecond pulsar. In addition to helping scientists detect gravitational waves, study of millisecond pulars also can yield important new information about other effects of General Relativity and about fundamental particle physics. "This new ability to find many more millisecond pulsars really is a treasure chest that can yield many valuable gems of scientific discovery," Ransom said.
Inflationary gravitational waves in collapse scheme models
NASA Astrophysics Data System (ADS)
Mariani, Mauro; Bengochea, Gabriel R.; León, Gabriel
2016-01-01
The inflationary paradigm is an important cornerstone of the concordance cosmological model. However, standard inflation cannot fully address the transition from an early homogeneous and isotropic stage, to another one lacking such symmetries corresponding to our present universe. In previous works, a self-induced collapse of the wave function has been suggested as the missing ingredient of inflation. Most of the analysis regarding the collapse hypothesis has been solely focused on the characteristics of the spectrum associated to scalar perturbations, and within a semiclassical gravity framework. In this Letter, working in terms of a joint metric-matter quantization for inflation, we calculate, for the first time, the tensor power spectrum and the tensor-to-scalar ratio corresponding to the amplitude of primordial gravitational waves resulting from considering a generic self-induced collapse.
Gravitational waves and short gamma ray bursts
NASA Astrophysics Data System (ADS)
Predoi, Valeriu
2012-07-01
Short hard gamma-ray bursts (GRB) are believed to be produced by compact binary coalescences (CBC) { either double neutron stars or neutron star{black hole binaries. The same source is expected to emit strong gravitational radiation, detectable with existing and planned gravitational wave observatories. The focus of this work is to describe a series of searches for gravitational waves (GW) from compact binary coalescence (CBC) events triggered by short gamma-ray burst detections. Specifically, we will present the motivation, frameworks, implementations and results of searches for GW associated with short gamma-ray bursts detected by Swift, Fermi{GBM and the InterPlanetary Network (IPN) gamma-ray detectors. We will begin by presenting the main concepts that lay the foundation of gravitational waves emission, as they are formulated in the theory of General Relativity; we will also brie y describe the operational principles of GW detectors, together with explaining the main challenges that the GW detection process is faced with. Further, we will motivate the use of observations in the electromagnetic (EM) band as triggers for GW searches, with an emphasis on possible EM signals from CBC events. We will briefly present the data analysis techniques including concepts as matched{filtering through a collection of theoretical GW waveforms, signal{to{ noise ratio, coincident and coherent analysis approaches, signal{based veto tests and detection candidates' ranking. We will use two different GW{GRB search examples to illustrate the use of the existing coincident and coherent analysis methods. We will also present a series of techniques meant to improve the sensitivity of existing GW triggered searches. These include shifting background data in time in order to obtain extended coincident data and setting a prior on the GRB inclination angle, in accordance with astrophysical observations, in order to restrict the searched parameter space. We will describe the GW data analysis
Einstein's Symphony: A Gravitational Wave Voyage Through Space and Time
NASA Astrophysics Data System (ADS)
Shapiro Key, Joey; Yunes, Nico; Grimberg, Irene
2015-01-01
Einstein's Symphony: A Gravitational Wave Voyage Through Space and Time is a gravitational wave astronomy planetarium show in production by a collaboration of scientists, filmmakers, and artisits from the Center for Gravitational Wave Astonomy (CGWA) at the University of Texas at Brownsville (UTB) and Montana State University (MSU). The project builds on the success of the interdisciplinary Celebrating Einstein collaboration. The artists and scientists who created the A Shout Across Time original film and the Black (W)hole immersive art installation for Celebrating Einstein are teaming with the Museum of the Rockies Taylor Planetarium staff and students to create a new full dome Digistar planetarium show that will be freely and widely distributed to planetaria in the US and abroad. The show uses images and animations filmed and collected for A Shout Across Time and for Black (W)hole as well as new images and animations and a new soundtrack composed and produced by the MSU School of Music to use the full capability of planetarium sound systems. The planetarium show will be narrated with ideas drawn from the Celebrating Einstein danced lecture on gravitational waves that the collaboration produced. The combination of products, resources, and team members assembled for this project allows us to create an original planetarium show for a fraction of the cost of a typical show. In addition, STEM education materials for G6-12 students and teachers will be provided to complement and support the show. This project is supported by the Texas Space Grant Consortium (TSGC), Montana Space Grant Consortium (MSGC), and the American Physical Society (APS).
The next detectors for gravitational wave astronomy
NASA Astrophysics Data System (ADS)
Blair, David; Ju, Li; Zhao, ChunNong; Wen, LinQing; Miao, HaiXing; Cai, RongGen; Gao, JiangRui; Lin, XueChun; Liu, Dong; Wu, Ling-An; Zhu, ZongHong; Hammond, Giles; Paik, Ho Jung; Fafone, Viviana; Rocchi, Alessio; Blair, Carl; Ma, YiQiu; Qin, JiaYi; Page, Michael
2015-12-01
This paper focuses on the next detectors for gravitational wave astronomy which will be required after the current ground based detectors have completed their initial observations, and probably achieved the first direct detection of gravitational waves. The next detectors will need to have greater sensitivity, while also enabling the world array of detectors to have improved angular resolution to allow localisation of signal sources. Sect. 1 of this paper begins by reviewing proposals for the next ground based detectors, and presents an analysis of the sensitivity of an 8 km armlength detector, which is proposed as a safe and cost-effective means to attain a 4-fold improvement in sensitivity. The scientific benefits of creating a pair of such detectors in China and Australia is emphasised. Sect. 2 of this paper discusses the high performance suspension systems for test masses that will be an essential component for future detectors, while sect. 3 discusses solutions to the problem of Newtonian noise which arise from fluctuations in gravity gradient forces acting on test masses. Such gravitational perturbations cannot be shielded, and set limits to low frequency sensitivity unless measured and suppressed. Sects. 4 and 5 address critical operational technologies that will be ongoing issues in future detectors. Sect. 4 addresses the design of thermal compensation systems needed in all high optical power interferometers operating at room temperature. Parametric instability control is addressed in sect. 5. Only recently proven to occur in Advanced LIGO, parametric instability phenomenon brings both risks and opportunities for future detectors. The path to future enhancements of detectors will come from quantum measurement technologies. Sect. 6 focuses on the use of optomechanical devices for obtaining enhanced sensitivity, while sect. 7 reviews a range of quantum measurement options.
Gravitational waves and the scale of inflation
NASA Astrophysics Data System (ADS)
Mirbabayi, Mehrdad; Senatore, Leonardo; Silverstein, Eva; Zaldarriaga, Matias
2015-03-01
We revisit alternative mechanisms of gravitational wave production during inflation and argue that they generically emit a non-negligible amount of scalar fluctuations. We find the scalar power is larger than the tensor power by a factor of order 1 /ɛ2. For an appreciable tensor contribution, the associated scalar emission completely dominates the zero-point fluctuations of the inflaton, resulting in a tensor-to-scalar ratio r ˜ɛ2. A more quantitative result can be obtained if one further assumes that gravitational waves are emitted by localized subhorizon processes, giving rmax≃0.3 ɛ2 . However, ɛ is generally time dependent, and this result for r depends on its instantaneous value during the production of the sources, rather than just its average value, somewhat relaxing constraints from the tilt ns. We calculate the scalar 3-point correlation function in the same class of models and show that non-Gaussianity cannot be made arbitrarily small, i.e. fN L≳1 , independently of the value of r . Possible exceptions in multifield scenarios are discussed.
Astrophysical Model Selection in Gravitational Wave Astronomy
NASA Technical Reports Server (NTRS)
Adams, Matthew R.; Cornish, Neil J.; Littenberg, Tyson B.
2012-01-01
Theoretical studies in gravitational wave astronomy have mostly focused on the information that can be extracted from individual detections, such as the mass of a binary system and its location in space. Here we consider how the information from multiple detections can be used to constrain astrophysical population models. This seemingly simple problem is made challenging by the high dimensionality and high degree of correlation in the parameter spaces that describe the signals, and by the complexity of the astrophysical models, which can also depend on a large number of parameters, some of which might not be directly constrained by the observations. We present a method for constraining population models using a hierarchical Bayesian modeling approach which simultaneously infers the source parameters and population model and provides the joint probability distributions for both. We illustrate this approach by considering the constraints that can be placed on population models for galactic white dwarf binaries using a future space-based gravitational wave detector. We find that a mission that is able to resolve approximately 5000 of the shortest period binaries will be able to constrain the population model parameters, including the chirp mass distribution and a characteristic galaxy disk radius to within a few percent. This compares favorably to existing bounds, where electromagnetic observations of stars in the galaxy constrain disk radii to within 20%.
Gravitational wave astronomy: needle in a haystack.
Cornish, Neil J
2013-02-13
A worldwide array of highly sensitive ground-based interferometers stands poised to usher in a new era in astronomy with the first direct detection of gravitational waves. The data from these instruments will provide a unique perspective on extreme astrophysical objects, such as neutron stars and black holes, and will allow us to test Einstein's theory of gravity in the strong field, dynamical regime. To fully realize these goals, we need to solve some challenging problems in signal processing and inference, such as finding rare and weak signals that are buried in non-stationary and non-Gaussian instrument noise, dealing with high-dimensional model spaces, and locating what are often extremely tight concentrations of posterior mass within the prior volume. Gravitational wave detection using space-based detectors and pulsar timing arrays bring with them the additional challenge of having to isolate individual signals that overlap one another in both time and frequency. Promising solutions to these problems will be discussed, along with some of the challenges that remain. PMID:23277598
An Atomic Gravitational Wave Interferometric Sensor (AGIS)
Dimopoulos, Savas; Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.; Rajendran, Surjeet; /SLAC /Stanford U., Phys. Dept.
2008-08-01
We propose two distinct atom interferometer gravitational wave detectors, one terrestrial and another satellite-based, utilizing the core technology of the Stanford 10m atom interferometer presently under construction. Each configuration compares two widely separated atom interferometers run using common lasers. The signal scales with the distance between the interferometers, which can be large since only the light travels over this distance, not the atoms. The terrestrial experiment with baseline {approx} 1 km can operate with strain sensitivity {approx} 10{sup -19}/{radical}Hz in the 1 Hz-10 Hz band, inaccessible to LIGO, and can detect gravitational waves from solar mass binaries out to megaparsec distances. The satellite experiment with baseline {approx} 1000 km can probe the same frequency spectrum as LISA with comparable strain sensitivity {approx} 10{sup -20}/{radical}Hz. The use of ballistic atoms (instead of mirrors) as inertial test masses improves systematics coming from vibrations, acceleration noise, and significantly reduces spacecraft control requirements. We analyze the backgrounds in this configuration and discuss methods for controlling them to the required levels.
Can JWST Follow Up on Gravitational-Wave Detections?
NASA Astrophysics Data System (ADS)
Kohler, Susanna
2016-02-01
Bitten by the gravitational-wave bug? While we await Thursdays press conference, heres some food for thought: if LIGO were able to detect gravitational waves from compact-object mergers, how could we follow up on the detections? A new study investigates whether the upcoming James Webb Space Telescope (JWST) will be able to observe electromagnetic signatures of some compact-object mergers.Hunting for MergersStudying compact-object mergers (mergers of black holes and neutron stars) can help us understand a wealth of subjects, like high-energy physics, how matter behaves at nuclear densities, how stars evolve, and how heavy elements in the universe were created.The Laser Interferometer Gravitational-Wave Observatory (LIGO) is searching for the signature ripples in spacetime identifying these mergers, but gravitational waves are squirrelly: LIGO will only be able to localize wave sources to tens of square degrees. If we want to find out more about any mergers LIGO discovers in gravitational waves, well need a follow-up search for electromagnetic counterparts with other observatories.The Kilonova KeyOne possible electromagnetic counterpart is kilonovae, explosions that can be produced during a merger of a binary neutron star or a neutron starblack hole system. If the neutron star is disrupted during the merger, some of the hot mass is flung outward and shines brightly by radioactive decay.Kilonovae are especially promising as electromagnetic counterparts to gravitational waves for three reasons:They emit isotropically, so the number of observable mergers isnt limited by relativistic beaming.They shine for a week, giving follow-up observatories time to search for them.The source location can beeasily recovered.The only problem? We dont currently have any sensitive survey instruments in the near-infrared band (where kilonova emission peaks) that can provide coverage over tens of square degrees. Luckily, we will soon have just the thing: JWST, launching in 2018!JWSTs
X ray timing observations and gravitational physics
NASA Technical Reports Server (NTRS)
Michelson, Peter F.; Wood, Kent S.
1989-01-01
Photon-rich x ray observations on bright compact galactic sources will make it possible to detect many fast processes that may occur in these systems on millisecond and submillisecond timescales. Many of these processes are of direct relevance to gravitational physics because they arise in regions of strong gravity near neutron stars and black holes where the dynamical timescales for compact objects of stellar mass are milliseconds. To date, such observations have been limited by the detector area and telemetry rates available. However, instruments such as the proposed X ray Large Array (XLA) would achieve collecting areas of about 100 sq m. This instrument has been described elsewhere (Wood and Michelson 1988) and was the subject of a recent prephase A feasibility study at Marshall Space Flight Center. Observations with an XLA class instrument will directly impact five primary areas of astrophysics research: the attempt to detect gravitational radiation, the study of black holes, the physics of mass accretion onto compact objects, the structure of neutron stars and nuclear matter, and the characterization of dark matter in the universe. Those observations are discussed that are most directly relevant to gravitational physics: the search for millisecond x ray pulsars that are potential sources of continuous gravitational radiation; and the use of x ray timing observations to probe the physical conditions in extreme relativistic regions of space near black holes, both stellar-sized and supermassive.
Optimizing vetoes for gravitational-wave transient searches
NASA Astrophysics Data System (ADS)
Essick, R.; Blackburn, L.; Katsavounidis, E.
2013-08-01
Interferometric gravitational-wave detectors like LIGO, GEO600 and Virgo record a surplus of information above and beyond possible gravitational-wave events. These auxiliary channels capture information about the state of the detector and its surroundings which can be used to infer potential terrestrial noise sources of some gravitational-wave-like events. We present an algorithm addressing the ordering (or equivalently optimizing) of such information from auxiliary systems in gravitational-wave detectors to establish veto conditions in searches for gravitational-wave transients. The procedure was used to identify vetoes for searches for unmodeled transients by the LIGO and Virgo collaborations during their science runs from 2005 through 2007. In this work we present the details of the algorithm; we also use a limited amount of data from LIGO's past runs in order to examine the method, compare it with other methods, and identify its potential to characterize the instruments themselves. We examine the dependence of receiver operating characteristic curves on the various parameters of the veto method and the implementation on real data. We find that the method robustly determines important auxiliary channels, ordering them by the apparent strength of their correlations to the gravitational-wave channel. This list can substantially reduce the background of noise events in the gravitational-wave data. In this way it can identify the source of glitches in the detector as well as assist in establishing confidence in the detection of gravitational-wave transients.
Searches for continuous gravitational waves with LIGO and GEO600
NASA Astrophysics Data System (ADS)
Landry, M.
2008-02-01
Current searches for astrophysically generated gravitational waves include the ground-based interferometers GEO600 and LIGO. The sensitive band of the detectors is at audio frequencies, from a few tens of Hz to several kHz. We report on efforts to search the data from these detectors for gravitational waves from spinning compact objects such as neutron or quark stars.
Gravitational wave astronomy - astronomy of the 21st century
NASA Astrophysics Data System (ADS)
Dhurandhar, S. V.
2011-03-01
An enigmatic prediction of Einstein's general theory of relativity is gravitational waves. With the observed decay in the orbit of the Hulse-Taylor binary pulsar agreeing within a fraction of a percent with the theoretically computed decay from Einstein's theory, the existence of gravitational waves was firmly established. Currently there is a worldwide effort to detect gravitational waves with inteferometric gravitational wave observatories or detectors and several such detectors have been built or being built. The initial detectors have reached their design sensitivities and now the effort is on to construct advanced detectors which are expected to detect gravitational waves from astrophysical sources. The era of gravitational wave astronomy has arrived. This article describes the worldwide effort which includes the effort on the Indian front - the IndIGO project -, the principle underlying interferometric detectors both on ground and in space, the principal noise sources that plague such detectors, the astrophysical sources of gravitational waves that one expects to detect by these detectors and some glimpse of the data analysis methods involved in extracting the very weak gravitational wave signals from detector noise.
Gravitational wave astronomy-- astronomy of the 21st century
NASA Astrophysics Data System (ADS)
Dhurandhar, S. V.
2011-12-01
An enigmatic prediction of Einstein's general theory of relativity is gravitational waves. With the observed decay in the orbit of the Hulse-Taylor binary pulsar agreeing within a fraction of a percent with the theoretically computed decay from Einstein's theory, the existence of gravitational waves was firmly established. Currently there is a worldwide effort to detect gravitational waves with inteferometric gravitational wave observatories or detectors and several such detectors have been built or are being built. The initial detectors have reached their design sensitivities and now the effort is on to construct advanced detectors which are expected to detect gravitational waves from astrophysical sources. The era of gravitational wave astronomy has arrived. This article describes the worldwide effort which includes the effort on the Indian front-- the IndIGO project --, the principle underlying interferometric detectors both on ground and in space, the principal noise sources that plague such detectors, the astrophysical sources of gravitational waves that one expects to detect by these detectors and some glimpse of the data analysis methods involved in extracting the very weak gravitational wave signals from detector noise.
Optimizing Vetoes for Gravitational-wave Transient Searches
NASA Technical Reports Server (NTRS)
Essick, R.; Blackburn, Lindy L.; Katsavounidis, E.
2014-01-01
Interferometric gravitational-wave detectors like LIGO, GEO600 and Virgo record a surplus of information above and beyond possible gravitational-wave events. These auxiliary channels capture information about the state of the detector and its surroundings which can be used to infer potential terrestrial noise sources of some gravitational-wave-like events. We present an algorithm addressing the ordering (or equivalently optimizing) of such information from auxiliary systems in gravitational-wave detectors to establish veto conditions in searches for gravitational-wave transients. The procedure was used to identify vetoes for searches for unmodelled transients by the LIGO and Virgo collaborations during their science runs from 2005 through 2007. In this work we present the details of the algorithm; we also use a limited amount of data from LIGO's past runs in order to examine the method, compare it with other methods, and identify its potential to characterize the instruments themselves. We examine the dependence of Receiver Operating Characteristic curves on the various parameters of the veto method and the implementation on real data. We find that the method robustly determines important auxiliary channels, ordering them by the apparent strength of their correlations to the gravitational-wave channel. This list can substantially reduce the background of noise events in the gravitational-wave data. In this way it can identify the source of glitches in the detector as well as assist in establishing confidence in the detection of gravitational-wave transients.
Gravitational wave emission from binary supermassive black holes
NASA Astrophysics Data System (ADS)
Sesana, A.
2013-12-01
Massive black hole binaries (MBHBs) are unavoidable outcomes of the hierarchical structure formation process, and, according to the theory of general relativity, are expected to be the loudest gravitational wave (GW) sources in the Universe. In this paper I provide a broad overview of MBHBs as GW sources. After reviewing the basics of GW emission from binary systems and of MBHB formation, evolution and dynamics, I describe in some details the connection between binary properties and the emitted gravitational waveform. Direct GW observations will provide an unprecedented wealth of information about the physical nature and the astrophysical properties of these extreme objects, allowing to reconstruct their cosmic history, dynamics and coupling with their dense stellar and gaseous environment. In this context I describe ongoing and future efforts to make a direct detection with space based interferometry and pulsar timing arrays, highlighting the invaluable scientific payouts of such enterprises.
Black Hole Coalescence: The Gravitational Wave Driven Phase
NASA Technical Reports Server (NTRS)
Schnittman, Jeremy D.
2011-01-01
When two supermassive black holes (SMBHS) approach within 1-10 mpc, gravitational wave (GW) losses begin to dominate the evolution of the binary, pushing the system to merge in a relatively small time. During this final inspiral regime, the system will emit copious energy in GWs, which should be directly detectable by pulsar timing arrays and space-based interferometers. At the same time, any gas or stars in the immediate vicinity of the merging 5MBHs can get heated and produce bright electromagnetic (EM) counterparts to the GW signals. We present here a number of possible mechanisms by which simultaneous EM and GW signals will yield valuable new information about galaxy evolution, accretion disk dynamics, and fundamental physics in the most extreme gravitational fields.
Gravitational waves from the fragmentation of a supersymmetric condensate
Kusenko, Alexander; Mazumdar, Anupam; Multamaeki, Tuomas
2009-06-15
We discuss the production of gravity waves from the fragmentation of a supersymmetric condensate in the early Universe. Supersymmetry predicts the existence of flat directions in the potential. At the end of inflation, the scalar fields develop large time-dependent vacuum expectation values along these flat directions. Under some general conditions, the scalar condensates undergo a fragmentation into nontopological solitons, Q-balls. We study this process numerically and confirm the recent analytical calculations showing that it can produce gravity waves observable by the Advanced Laser Interferometer Gravitational Wave Observatory, Laser Interferometer Space Antenna, and Big Bang Observer. The fragmentation can generate gravity waves with an amplitude as large as {omega}{sub GW}h{sup 2}{approx}10{sup -11} and with a peak frequency ranging from 1 mHz to 10 Hz, depending on the parameters. The discovery of such a relic gravitational background radiation can open a new window on the physics at the high scales, even if supersymmetry is broken well above the electroweak scale.
Gravitational-wave detection using redshifted 21-cm observations
Bharadwaj, Somnath; Guha Sarkar, Tapomoy
2009-06-15
A gravitational-wave traversing the line of sight to a distant source produces a frequency shift which contributes to redshift space distortion. As a consequence, gravitational waves are imprinted as density fluctuations in redshift space. The gravitational-wave contribution to the redshift space power spectrum has a different {mu} dependence as compared to the dominant contribution from peculiar velocities. This, in principle, allows the two signals to be separated. The prospect of a detection is most favorable at the highest observable redshift z. Observations of redshifted 21-cm radiation from neutral hydrogen hold the possibility of probing very high redshifts. We consider the possibility of detecting primordial gravitational waves using the redshift space neutral hydrogen power spectrum. However, we find that the gravitational-wave signal, though present, will not be detectable on superhorizon scales because of cosmic variance and on subhorizon scales where the signal is highly suppressed.
Directed search for continuous gravitational waves from the Galactic center
NASA Astrophysics Data System (ADS)
Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann, G.; Berliner, J. M.; Bertolini, A.; Bessis, D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Bose, S.; Bosi, L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Colombini, M.; Constancio, M., Jr.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Deleeuw, E.; Deléglise, S.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.; Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.
2013-11-01
We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO’s fifth science run from two LIGO detectors. The search uses a semicoherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of first-order spindown values down to -7.86×10-8Hz/s at the highest frequency. No gravitational waves were detected. The 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic center are ˜3.35×10-25 for frequencies near 150 Hz. These upper limits are the most constraining to date for a large-parameter-space search for continuous gravitational wave signals.
Gravitational waves from the cosmological QCD transition
NASA Astrophysics Data System (ADS)
Mourão Roque, V. R. C.; Roque, G. Lugones o.; Lugones, G.
2014-09-01
We determine the minimum fluctuations in the cosmological QCD phase transition that could be detectable by the eLISA/NGO gravitational wave observatory. To this end, we performed several hydrodynamical simulations using a state-of-the-art equation of state derived from lattice QCD simulations. Based on the fact that the viscosity per entropy density of the quark gluon plasma obtained from heavy-ion collision experiments at the RHIC and the LHC is extremely small, we considered a non-viscous fluid in our simulations. Several previous works about this transition considered a first order transition that generates turbulence which follows a Kolmogorov power law. We show that for the QCD crossover transition the turbulent spectrum must be very different because there is no viscosity and no source of continuous energy injection. As a consequence, a large amount of kinetic energy accumulates at the smallest scales. From the hydrodynamic simulations, we have obtained the spectrum of the gravitational radiation emitted by the motion of the fluid, finding that, if typical velocity and temperature fluctuations have an amplitude Δ v /c ≳ 10-2 and/or Δ T/T_c ≳ 10-3, they would be detected by eLISA/NGO at frequencies larger than ˜ 10-4 Hz.
DETECTING GRAVITATIONAL WAVE MEMORY WITH PULSAR TIMING
Cordes, J. M.; Jenet, F. A. E-mail: merlyn@phys.utb.edu
2012-06-10
We compare the detectability of gravitational bursts passing through the solar system with those passing near each millisecond pulsar in an N-pulsar timing array. The sensitivity to Earth-passing bursts can exploit the correlation expected in pulse arrival times while pulsar-passing bursts, though uncorrelated between objects, provide an N-fold increase in overall time baseline that can compensate for the lower sensitivity. Bursts with memory from mergers of supermassive black holes produce step functions in apparent spin frequency that are the easiest to detect in pulsar timing. We show that the burst rate and amplitude distribution, while strongly dependent on inadequately known cosmological evolution, may favor detection in the pulsar terms rather than the Earth timing perturbations. Any contamination of timing data by red spin noise makes burst detection more difficult because both signals grow with the length of the time data span T. Furthermore, the different bursts that could appear in one or more data sets of length T Almost-Equal-To 10 yr also affect the detectability of the gravitational wave stochastic background that, like spin noise, has a red power spectrum. A burst with memory is a worthwhile target in the timing of multiple pulsars in a globular cluster because it should produce a correlated signal with a time delay of less than about 10 years in some cases.
Gravitational wave: gamma-ray burst connections.
Hough, Jim
2007-05-15
After 35 years of experimental research, we are rapidly approaching the point at which gravitational waves (GWs) from astrophysical sources may be directly detected by the long-baseline detectors LIGO (USA), GEO 600 (Germany/UK), VIRGO (Italy/France) and TAMA 300 (Japan), which are now in or coming into operation.A promising source of GWs is the coalescence of compact binary systems, events which are now believed to be the origin of short gamma-ray bursts (GRBs). In this paper, a brief review of the state of the art in detector development and exploitation will be given, with particular relevance to a search for signals associated with GRBs, and plans for the future will be discussed. PMID:17293333
Beyond LISA: Exploring future gravitational wave missions
NASA Astrophysics Data System (ADS)
Crowder, Jeff; Cornish, Neil J.
2005-10-01
The Advanced Laser Interferometer Antenna (ALIA) and the Big Bang Observer (BBO) have been proposed as follow on missions to the Laser Interferometer Space Antenna (LISA). Here we study the capabilities of these observatories, and how they relate to the science goals of the missions. We find that the Advanced Laser Interferometer Antenna in Stereo (ALIAS), our proposed extension to the ALIA mission, will go considerably further toward meeting ALIA’s main scientific goal of studying intermediate mass black holes. We also compare the capabilities of LISA to a related extension of the LISA mission, the Laser Interferometer Space Antenna in Stereo (LISAS). Additionally, we find that the initial deployment phase of the BBO would be sufficient to address the BBO’s key scientific goal of detecting the Gravitational Wave Background, while still providing detailed information about foreground sources.
Gravitational wave triggered searches for failed supernovae
NASA Astrophysics Data System (ADS)
Annis, James; Dark Energy Survey Collaboration
2016-03-01
Stellar core collapses occur to all stars of sufficiently high mass and often result in supernovae. A small fraction of supergiant stars, however, are thought to collapse directly into black holes without producing supernovae. A survey of such ``failed'' supernovae would require monitoring millions of supergiants for several years. That is very challenging even for current surveys. With the start of the Advanced LIGO science run, we investigate the possibility of detecting failed supernovae by looking for missing supergiants associated with gravitational wave triggers. We use the Dark Energy Camera (DECam). Our project is a joint effort between the community and the Dark Energy Survey (DES) collaboration. In this talk we report on our ongoing efforts and discuss prospects for future searches.
Broadband Resonant Mass Gravitational Wave Detection
NASA Astrophysics Data System (ADS)
Aguiar, Odylio D.; Barroso, Joaquim J.; Marinho, Rubens M.; Pimentel, Guilherme L.; Tobar, Michael E.
By changing from a resonant multimode paradigm to a free mass paradigm for transducers in resonant mass gravitational wave detection, an array of six spheres can achieve a sensitivity response curve competitive with interferometers, being as sensitive as GEO600 and TAMA300 in the 3-6 kHz band and more sensitive than LIGO for 50% of the 6-10 kHz band. This approach has additional benefits. First, due to the relatively inexpensive nature of this technology (~US$1 million), it is accessible to a broader part of the world's scientific community. Additionally, spherical resonant mass detectors have the ability to discern both the direction and polarization resolutions.
Constraining the braneworld with gravitational wave observations.
McWilliams, Sean T
2010-04-01
Some braneworld models may have observable consequences that, if detected, would validate a requisite element of string theory. In the infinite Randall-Sundrum model (RS2), the AdS radius of curvature, l, of the extra dimension supports a single bound state of the massless graviton on the brane, thereby reproducing Newtonian gravity in the weak-field limit. However, using the AdS/CFT correspondence, it has been suggested that one possible consequence of RS2 is an enormous increase in Hawking radiation emitted by black holes. We utilize this possibility to derive two novel methods for constraining l via gravitational wave measurements. We show that the EMRI event rate detected by LISA can constrain l at the approximately 1 microm level for optimal cases, while the observation of a single galactic black hole binary with LISA results in an optimal constraint of l < or = 5 microm. PMID:20481929
Searching for gravitational waves from binary coalescence
NASA Astrophysics Data System (ADS)
Babak, S.; Biswas, R.; Brady, P. R.; Brown, D. A.; Cannon, K.; Capano, C. D.; Clayton, J. H.; Cokelaer, T.; Creighton, J. D. E.; Dent, T.; Dietz, A.; Fairhurst, S.; Fotopoulos, N.; González, G.; Hanna, C.; Harry, I. W.; Jones, G.; Keppel, D.; McKechan, D. J. A.; Pekowsky, L.; Privitera, S.; Robinson, C.; Rodriguez, A. C.; Sathyaprakash, B. S.; Sengupta, A. S.; Vallisneri, M.; Vaulin, R.; Weinstein, A. J.
2013-01-01
We describe the implementation of a search for gravitational waves from compact binary coalescences in LIGO and Virgo data. This all-sky, all-time, multidetector search for binary coalescence has been used to search data taken in recent LIGO and Virgo runs. The search is built around a matched filter analysis of the data, augmented by numerous signal consistency tests designed to distinguish artifacts of non-Gaussian detector noise from potential detections. We demonstrate the search performance using Gaussian noise and data from the fifth LIGO science run and demonstrate that the signal consistency tests are capable of mitigating the effect of non-Gaussian noise and providing a sensitivity comparable to that achieved in Gaussian noise.
Gravitational waves in open de Sitter space
NASA Astrophysics Data System (ADS)
Hawking, S. W.; Hertog, Thomas; Turok, Neil
2000-09-01
We compute the spectrum of primordial gravitational wave perturbations in open de Sitter spacetime. The background spacetime is taken to be the continuation of an O(5) symmetric instanton saddle point of the Euclidean no boundary path integral. The two-point tensor fluctuations are computed directly from the Euclidean path integral. The Euclidean correlator is then analytically continued into the Lorentzian region where it describes the quantum mechanical vacuum fluctuations of the graviton field. Unlike the results of earlier work, the correlator is shown to be unique and well behaved in the infrared. We show that the infrared divergence found in previous calculations is due to the contribution of a discrete gauge mode inadvertently included in the spectrum.
Black Holes, Gravitational Waves, and LISA
NASA Technical Reports Server (NTRS)
Baker, John
2009-01-01
Binary black hole mergers are central to many key science objectives of the Laser Interferometer Space Antenna (LISA). For many systems the strongest part of the signal is only understood by numerical simulations. Gravitational wave emissions are understood by simulations of vacuum General Relativity (GR). I discuss numerical simulation results from the perspective of LISA's needs, with indications of work that remains to be done. Some exciting scientific opportunities associated with LISA observations would be greatly enhanced if prompt electromagnetic signature could be associated. I discuss simulations to explore this possibility. Numerical simulations are important now for clarifying LISA's science potential and planning the mission. We also consider how numerical simulations might be applied at the time of LISA's operation.
Optimal directed searches for continuous gravitational waves
NASA Astrophysics Data System (ADS)
Ming, Jing; Krishnan, Badri; Papa, Maria Alessandra; Aulbert, Carsten; Fehrmann, Henning
2016-03-01
Wide parameter space searches for long-lived continuous gravitational wave signals are computationally limited. It is therefore critically important that the available computational resources are used rationally. In this paper we consider directed searches, i.e., targets for which the sky position is known accurately but the frequency and spin-down parameters are completely unknown. Given a list of such potential astrophysical targets, we therefore need to prioritize. On which target(s) should we spend scarce computing resources? What parameter space region in frequency and spin-down should we search through? Finally, what is the optimal search setup that we should use? In this paper we present a general framework that allows us to solve all three of these problems. This framework is based on maximizing the probability of making a detection subject to a constraint on the maximum available computational cost. We illustrate the method for a simplified problem.
Topics in gravitational-wave astronomy
NASA Astrophysics Data System (ADS)
O'Shaughnessy, R.
2004-09-01
Both the Laser Interferometer Gravitational Wave Observatory (LIGO) the Laser Interferometer Space Antenna (LISA) will over the next decade detect gravitational waves emitted by the motion of compact objects (e.g. black hole and neutron star binaries). This thesis presents methods to improve (i)LIGO detector quality, (ii)our knowledge of waveforms for certain LIGO and LISA sources, and (iii)models for the rate of detectability of a particular LISA source. (1)Plunge of compact object into a supermassive black hole: LISA should detect many inspirals of compact objects into supermassive black holes (˜105 107 M⊙ ). Since the inspiral of each compact object terminates shortly after the inspiralling object reaches its last stable orbit, the late-stage inspiral waveform provides insight into the location of the last stable orbit and strong-field relativity. I discovered that while LISA will easily see the overall inspiral (consisting of many cycles before plunge), the present LISA design will just miss detecting the waves emitted from the transition from inspiral to plunge. (2)Scheme to reduce thermoelastic noise in advanced LIGO: After its first upgrade, LIGO will have its sensitivity limited by thermoelastic noise. [Thermoelastic noise occurs because milimeter-scale thermal fluctuations in the mirror bulk expand and contract, causing the mirror surface to shimmer.] The interferometer's sensitivity could be enhanced substantially by reducing thermoelastic noise. In collaboration with Kip Thorne, Erika d'Ambrosio, Sergey Vyatchanin, and Sergey Strigin, I developed a proposal to reduce thermoelastic noise in advanced-LIGO by switching the LIGO cavity optics from simple spherical mirrors to a new, Mexican-hat shape. (3)Geometric-optics-based analysis of stability of symmetric-hyperbolic formulations of Einstein's equations : Einstein's equations must be evolved numerically to predict accurate waveforms for the late stages of binary black hole inspiral and merger. But no
Demorest, P. B.; Ransom, S.; Ferdman, R. D.; Kaspi, V. M.; Gonzalez, M. E.; Stairs, I. H.; Nice, D.; Arzoumanian, Z.; Brazier, A.; Cordes, J. M.; Burke-Spolaor, S.; Lazio, J.; Chamberlin, S. J.; Ellis, J.; Giampanis, S.; Finn, L. S.; Freire, P.; Jenet, F.; Lommen, A. N.; McLaughlin, M.; and others
2013-01-10
We present an analysis of high-precision pulsar timing data taken as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We have observed 17 pulsars for a span of roughly five years using the Green Bank and Arecibo radio telescopes. We analyze these data using standard pulsar timing models, with the addition of time-variable dispersion measure and frequency-variable pulse shape terms. Sub-microsecond timing residuals are obtained in nearly all cases, and the best rms timing residuals in this set are {approx}30-50 ns. We present methods for analyzing post-fit timing residuals for the presence of a gravitational wave signal with a specified spectral shape. These optimally take into account the timing fluctuation power removed by the model fit, and can be applied to either data from a single pulsar, or to a set of pulsars to detect a correlated signal. We apply these methods to our data set to set an upper limit on the strength of the nHz-frequency stochastic supermassive black hole gravitational wave background of h{sub c} (1 yr{sup -1}) < 7 Multiplication-Sign 10{sup -15} (95%). This result is dominated by the timing of the two best pulsars in the set, PSRs J1713+0747 and J1909-3744.
Black-Hole Binaries, Gravitational Waves, and Numerical Relativity
NASA Technical Reports Server (NTRS)
Kelly, Bernard J.; Centrella, Joan; Baker, John G.; Kelly, Bernard J.; vanMeter, James R.
2010-01-01
Understanding the predictions of general relativity for the dynamical interactions of two black holes has been a long-standing unsolved problem in theoretical physics. Black-hole mergers are monumental astrophysical events ' releasing tremendous amounts of energy in the form of gravitational radiation ' and are key sources for both ground- and spacebased gravitational wave detectors. The black-hole merger dynamics and the resulting gravitational waveforms can only he calculated through numerical simulations of Einstein's equations of general relativity. For many years, numerical relativists attempting to model these mergers encountered a host of problems, causing their codes to crash after just a fraction of a binary orbit cnuld be simulated. Recently ' however, a series of dramatic advances in numerical relativity has ' for the first time, allowed stable / robust black hole merger simulations. We chronicle this remarkable progress in the rapidly maturing field of numerical relativity, and the new understanding of black-hole binary dynamics that is emerging. We also discuss important applications of these fundamental physics results to astrophysics, to gravitationalwave astronomy, and in other areas.
Magnetar asteroseismology with long-term gravitational waves
Kashiyama, Kazumi; Ioka, Kunihito
2011-04-15
Magnetic flares and induced oscillations of magnetars (supermagnetized neutron stars) are promising sources of gravitational waves (GWs). We suggest that the GW emission, if any, would last longer than the observed x-ray quasiperiodic oscillations (X-QPOs), calling for longer-term GW analyses lasting a day to months, compared to current searches' durations. Like the pulsar timing, the oscillation frequency would also evolve with time because of the decay or reconfiguration of the magnetic field, which is crucial for the GW detection. With the observed GW frequency and its time-derivatives, we can probe the interior magnetic field strength of {approx}10{sup 16} G and its evolution to open a new GW asteroseismology with the next generation interferometers like the advanced laser interferometer gravitational wave observatory, the advanced Virgo gravitational wave detector at the European Gravitational Observatory, the Large-scale cryogenic gravitational wave telescope, and the Einstein telescope.
The LIGO Gravitational Wave Observatories:. Recent Results and Future Plans
NASA Astrophysics Data System (ADS)
Harry, G. M.; Adhikari, R.; Ballmer, S.; Bayer, K.; Betzwieser, J.; Bochner, B.; Burgess, R.; Cadonati, L.; Chatterji, S.; Corbitt, T.; Csatorday, P.; Fritschel, P.; Goda, K.; Hefetz, Y.; Katsavounidis, E.; Lawrence, R.; Macinnis, M.; Marin, A.; Mason, K.; Mavalvala, N.; Mittleman, R.; Ottaway, D. J.; Pratt, M.; Regimbau, T.; Richman, S.; Rollins, J.; Shoemaker, D. H.; Smith, M.; van Putten, M.; Weiss, R.; Aulbert, C.; Berukoff, S. J.; Cutler, C.; Grunewald, S.; Itoh, Y.; Krishnan, B.; Machenschalk, B.; Mohanty, S.; Mukherjee, S.; Naundorf, H.; Papa, M. A.; Schutz, B. F.; Sintes, A. M.; Williams, P. R.; Colacino, C.; Danzmann, K.; Freise, A.; Grote, H.; Heinzel, G.; Kawabe, K.; Kloevekorn, P.; Lück, H.; Mossavi, K.; Nagano, S.; Rüdiger, A.; Schilling, R.; Smith, J. R.; Weidner, A.; Willke, B.; Winkler, W.; Cusack, B. J.; McClelland, D. E.; Scott, S. M.; Searle, A. C.; Drever, R. W. P.; Tinto, M.; Williams, R.; Buonanno, A.; Chen, Y.; Thorne, K. S.; Vallisneri, M.; Abbott, B.; Anderson, S. B.; Araya, M.; Armandula, H.; Asiri, F.; Barish, B. C.; Barnes, M.; Barton, M. A.; Bhawal, B.; Billingsley, G.; Black, E.; Blackburn, K.; Bogue, L.; Bork, R.; Busby, D.; Cardenas, L.; Chandler, A.; Chapsky, J.; Charlton, P.; Coyne, D.; Creighton, T. D.; D'Ambrosio, E.; Desalvo, R.; Ding, H.; Edlund, J.; Ehrens, P.; Etzel, T.; Evans, M.; Farnham, D.; Fine, M.; Gillespie, A.; Grimmett, D.; Hartunian, A.; Heefner, J.; Hoang, P.; Hrynevych, M.; Ivanov, A.; Jones, L.; Jungwirth, D.; Kells, W.; King, C.; King, P.; Kozak, D.; Lazzarini, A.; Lei, M.; Libbrecht, K.; Lindquist, P.; Liu, S.; Logan, J.; Lyons, T. T.; Mageswaran, M.; Mailand, K.; Majid, W.; Mann, F.; Márka, S.; Maros, E.; Mason, J.; Meshkov, S.; Miyakawa, O.; Miyoki, S.; Mours, B.; Nocera, F.; Ouimette, D.; Pedraza, M.; Rao, S. R.; Redding, D.; Regehr, M. W.; Reilly, K. T.; Reithmaier, K.; Robison, L.; Romie, J.; Rose, D.; Russell, P.; Salzman, I.; Sanders, G. H.; Sannibale, V.; Schmidt, V.; Sears, B.; Seel, S.; Shawhan, P.; Sievers, L.; Smith, M. R.; Spero, R.; Sumner, M. C.; Sylvestre, J.; Takamori, A.; Tariq, H.; Taylor, R.; Tilav, S.; Torrie, C.; Tyler, W.; Vass, S.; Wallace, L.; Ware, B.; Webber, D.; Weinstein, A.; Wen, L.; Whitcomb, S. E.; Willems, P. A.; Wilson, A.; Yamamoto, H.; Zhang, L.; Zweizig, J.; Ganezer, K. S.; Babak, S.; Balasubramanian, R.; Churches, D.; Davies, R.; Sathyaprakash, B.; Taylor, I.; Christensen, N.; Ebeling, C.; Flanagan, É.; Nash, T.; Penn, S.; Dhurandar, S.; Nayak, R.; Sengupta, A. S.; Barker, D.; Barker-Patton, C.; Bland-Weaver, B.; Cook, D.; Gray, C.; Guenther, M.; Hindman, N.; Landry, M.; Lubiński, M.; Matherny, O.; Matone, L.; McCarthy, R.; Mendell, G.; Moreno, G.; Myers, J.; Parameswariah, V.; Raab, F.; Radkins, H.; Ryan, K.; Savage, R.; Schwinberg, P.; Sigg, D.; Vorvick, C.; Worden, J.; Abbott, R.; Carter, K.; Coles, M.; Evans, T.; Frolov, V.; Fyffe, M.; Gretarsson, A. M.; Hammond, M.; Hanson, J.; Kern, J.; Khan, A.; Kovalik, J.; Langdale, J.; Lormand, M.; O'Reilly, B.; Overmier, H.; Parameswariah, C.; Riesen, R.; Rizzi, A.; Roddy, S.; Sibley, A.; Stapfer, G.; Traylor, G.; Watts, K.; Wooley, R.; Yakushin, I.; Zucker, M.; Chickarmane, V.; Daw, E.; Giaime, J. A.; González, G.; Hamilton, W. O.; Johnson, W. W.; Wen, S.; Zotov, N.; McHugh, M.; Whelan, J. T.; Walther, H.; Ageev, A.; Bilenko, I. A.; Braginsky, V. B.; Mitrofanov, V. P.; Tokmakov, K. V.; Vyachanin, S. P.; Camp, J. B.; Kawamura, S.; Belczynski, K.; Grandclément, P.; Kalogera, V.; Kim, C.; Nutzman, P.; Olson, T.; Yoshida, S.; Beausoleil, R.; Bullington, A.; Byer, R. L.; Debra, D.; Fejer, M. M.; Gustafson, E.; Hardham, C.; Hennessy, M.; Hua, W.; Lantz, B.; Robertson, N. A.; Saulson, P. R.; Finn, L. S.; Hepler, N.; Owen, B. J.; Rotthoff, E.; Schlaufman, K.; Shapiro, C. A.; Stuver, A.; Summerscales, T.; Sutton, P. J.; Tibbits, M.; Winjum, B. J.; Anderson, W. G.; Díaz, M.; Johnston, W.; Romano, J. D.; Torres, C.; Ugolini, D.; Aufmuth, P.; Brozek, S.; Fallnich, C.; Goßler, S.; Heng, I. S.; Heurs, M.; Kötter, K.; Leonhardt, V.; Malec, M.; Quetschke, V.; Schrempel, M.; Traeger, S.; Weiland, U.; Welling, H.; Zawischa, I.; Ingley, R.; Messenger, C.; Vecchio, A.; Amin, R.; Castiglione, J.; Coldwell, R.; Delker, T.; Klimenko, S.; Mitselmakher, G.; Mueller, G.; Rakhmanov, M.; Reitze, D. H.; Rong, H.; Sazonov, A.; Shu, Q. Z.; Tanner, D. B.; Whiting, B. F.; Wise, S.; Barr, B.; Bennett, R.; Cagnoli, G.; Cantley, C. A.; Casey, M. M.; Crooks, D. R. M.; Dupuis, R. J.; Elliffe, E. J.; Grant, A.; Heptonstall, A.; Hewitson, M.; Hough, J.; Jennrich, O.; Killbourn, S.; Killow, C. J.; McNamara, P.; Newton, G.; Pitkin, M.; Plissi, M.; Robertson, D. I.; Rowan, S.; Skeldon, K.; Sneddon, P.; Strain, K. A.; Ward, H.; Woan, G.; Chin, D.; Gustafson, R.; Riles, K.; Brau, J. E.; Frey, R.; Ito, M.; Leonor, I.
2006-02-01
The LIGO interferometers are operating as gravitational wave observatories, with a noise level near an order of magnitude of the goal and the first scientific data recently taken. This data has been analyzed for four different categories of gravitational wave sources; millisecond bursts, inspiralling binary neutron stars, periodic waves from a known pulsar, and stochastic background. Research and development is also underway for the next generation LIGO detector, Advanced LIGO.
Earth-orbiting resonant-mass gravitational wave detectors
NASA Technical Reports Server (NTRS)
Paik, Ho Jung
1989-01-01
Earth-based gravitational wave detectors suffer from the need to support the large antenna masses against the earth's gravity without transmitting a significant amount of seismic noise. Passive vibration isolation is difficult to achieve below 1 Hz on the earth. Vibration-free space environment thus gives an opportunity to extend the frequency window of gravitational wave detection to ultralow frequencies. The weightless condition of a space laboratory also enables construction of a highly symmetric multimode antenna which is capable of resolving the direction of the source and the polarization of the incoming wave without resorting to multiantenna coincidence. Two types of earth-orbiting resonant-mass gravitational wave detectors are considered. One is a skyhook gravitational wave detector, proposed by Braginsky and Thorne (1985). The other is a spherical detector, proposed by Forward (1971) and analyzed by Wagoner and Paik (1976).
Interferometric Gravitational-Wave Detectors: Current Status and Future Plans
NASA Astrophysics Data System (ADS)
Ando, Masaki
2008-08-01
Constructions of the first-generation interferometric gravitational-wave detectors, such as LIGO, VIRGO, GEO600, and TAMA300, have been finished, and long-term observation runs have been carried out as a global network. These data are analyzed in searches for gravitational-wave signals, and are starting to produce scientific results. In addition, next-generation detectors, which will have sufficient sensitivity to directly detect gravitational waves, are being proposed. In this article, the status of the current detectors, scientific results obtained form observation data, and future interferometric detector plans are reviewed.
Optical frequency standards for gravitational wave detection using satellite velocimetry
NASA Astrophysics Data System (ADS)
Vutha, Amar
2015-04-01
Satellite Doppler velocimetry, building on the work of Kaufmann and Estabrook and Wahlquist, is a complementary technique to interferometric methods of gravitational wave detection. This method is based on the fact that the gravitational wave amplitude appears in the apparent Doppler shift of photons propagating from an emitter to a receiver. This apparent Doppler shift can be resolved provided that a frequency standard, capable of quickly averaging down to a high stability, is available. We present a design for a space-capable optical atomic frequency standard, and analyze the sensitivity of satellite Doppler velocimetry for gravitational wave astronomy in the milli-hertz frequency band.
Observable induced gravitational waves from an early matter phase
Alabidi, Laila; Sasaki, Misao; Kohri, Kazunori; Sendouda, Yuuiti E-mail: kohri@post.kek.jp E-mail: sendouda@cc.hirosaki-u.ac.jp
2013-05-01
Assuming that inflation is succeeded by a phase of matter domination, which corresponds to a low temperature of reheating T{sub r} < 10{sup 9}GeV, we evaluate the spectra of gravitational waves induced in the post-inflationary universe. We work with models of hilltop-inflation with an enhanced primordial scalar spectrum on small scales, which can potentially lead to the formation of primordial black holes. We find that a lower reheat temperature leads to the production of gravitational waves with energy densities within the ranges of both space and earth based gravitational wave detectors.
Composite gravitational-wave detection of compact binary coalescence
Cannon, Kipp; Hanna, Chad; Keppel, Drew; Searle, Antony C.
2011-04-15
The detection of gravitational waves from compact binaries relies on a computationally burdensome processing of gravitational-wave detector data. The parameter space of compact-binary-coalescence gravitational waves is large and optimal detection strategies often require nearly redundant calculations. Previously, it has been shown that singular value decomposition of search filters removes redundancy. Here we will demonstrate the use of singular value decomposition for a composite detection statistic. This can greatly improve the prospects for a computationally feasible rapid detection scheme across a large compact binary parameter space.
Gravitational waves from kinks on infinite cosmic strings
Kawasaki, Masahiro; Miyamoto, Koichi; Nakayama, Kazunori
2010-05-15
Gravitational waves emitted by kinks on infinite strings are investigated using detailed estimations of the kink distribution on infinite strings. We find that gravitational waves from kinks can be detected by future pulsar timing experiments such as SKA for an appropriate value of the string tension, if the typical size of string loops is much smaller than the horizon at their formation. Moreover, the gravitational wave spectrum depends on the thermal history of the Universe and hence it can be used as a probe into the early evolution of the Universe.
Merging ``real'' neutron stars for gravitational waves and electromagnetic counterparts
NASA Astrophysics Data System (ADS)
Duez, Matthew
2014-03-01
Having more-or-less succeeded in learning to stably evolve Einstein's equations, numerical relativity is taking the leap to including the physics of neutron stars, which will enable us to construct truly realistic pictures of neutron star-neutron star and black hole-neutron star binary mergers. The neutron star profile affects late inspirals and mergers, leaving its imprint on gravitational waveforms and electromagnetic counterpart signals. Furthermore, we expect neutrino radiation, magnetic field, and nuclear recombination effects to drive the post-merger evolution. In this talk, I will describe some recent neutron star merger simulations combining nuclear physics and general relativity. The goal is to connect assumptions about the nuclear equation of state and the premerger binary to resulting binary trajectories, matter outflows, accretion disk dynamics, and neutrino energy output. These can then hopefully be connected to observable signals in the form of gravitational waves, kilonovae, and gamma ray bursts. It is found that an interesting variety of disks, outflows, and neutrino bursts are possible. Connections to observables are being attempted by tracking nuclear reactions in tidal ejecta and estimating energy injection to gamma ray bursts from neutrino annihilation and other sources. Meanwhile, non-vacuum inspiral simulations are finally approaching the length and accuracy needed for interesting comparisons with binary black hole waveforms and post-Newtonian predictions, these being steps toward a reliable characterization of the imprint of the nuclear equation of state on the gravitational waves. The speaker acknowledges support from NASA Grant No. NNX11AC37G and NSF Grant PHY-1068243.
Numerical Relativity, Black Hole Mergers, and Gravitational Waves: Part I
NASA Technical Reports Server (NTRS)
Centrella, Joan
2012-01-01
This series of 3 lectures will present recent developments in numerical relativity, and their applications to simulating black hole mergers and computing the resulting gravitational waveforms. In this first lecture, we introduce the basic ideas of numerical relativity, highlighting the challenges that arise in simulating gravitational wave sources on a computer.