## [astro-ph/0504538] Self-interaction spin effects in inspiralling compact binaries

Authors: Balázs Mikóczi, Mátyás Vasúth, László Á. Gergely

Date: Mon, 25 Apr 2005

Abstract: Gravitational radiation drives compact binaries through an inspiral phase towards a final coalescence. For binaries with spin, mass quadrupole and magnetic dipole moments, various contributions add to this process, which is characterized by the rate of increase $df/dt$ of the gravitational wave frequency and the number $\mathcal{N}$ of gravitational wave cycles left until the final coalescence. We present here all contributions to $df/dt$ and $\mathcal{N}$ up to the second post-Newtonian order. Among them we give for the first time the contributions due to the self-interaction of individual spins. These are shown to be commensurable with the proper spin-spin contributions for the recently discovered J0737-3039 double pulsar, and argued to represent the first corrections to the Lense-Thirring approach.

#### Apr 27, 2005

0504538 (/preprints/astro-ph)
2005-04-27, 11:11 

## [gr-qc/0504116] Empirical Foundations of Relativistic Gravity

Authors: Wei-Tou Ni

Date: Sun, 24 Apr 2005

Abstract: In 1859, Le Verrier discovered the mercury perihelion advance anomaly. This anomaly turned out to be the first relativistic-gravity effect observed. During the 141 years to 2000, the precisions of laboratory and space experiments, and astrophysical and cosmological observations on relativistic gravity have been improved by 3 orders of magnitude. In 1999, we envisaged a 3-6 order improvement in the next 30 years in all directions of tests of relativistic gravity. In 2000, the interferometric gravitational wave detectors began their runs to accumulate data. In 2003, the measurement of relativistic Shapiro time-delay of the Cassini spacecraft determined the relativistic-gravity parameter gamma&#947; with a 1.5-order improvement. In October 2004, Ciufolini and Pavlis reported a measurement of the Lense-Thirring effect on the LAGEOS and LAGEOS2 satellites to 10 percent of the value predicted by general relativity. In April 2004, Gravity Probe B was launched and has been accumulating science data for more than 170 days now. MICROSCOPE is on its way for a 2007 launch to test Galileo equivalence principle to 10-15. STEP (Satellite Test of Equivalence Principle), and ASTROD (Astrodynamical Space Test of Relativity using Optical Devices) are in the good planning stage. Various astrophysical tests and cosmological tests of relativistic gravity will reach precision and ultra-precision stages. Clock tests and atomic interferometry tests of relativistic gravity will reach an ever-increasing precision. These will give revived interest and development both in experimental and theoretical aspects of gravity, and may lead to answers to some profound questions of gravity and the cosmos.

#### Apr 26, 2005

0504116 (/preprints/gr-qc)
2005-04-26, 13:59 

## [gr-qc/0504112] The White Dwarf -- White Dwarf galactic background in the LISA data

Authors: Jeffrey A. Edlund, Massimo Tinto, Andrzej Krolak, Gijs Nelemans

Date: Fri, 22 Apr 2005

Abstract: LISA (Laser Interferometer Space Antenna) is a proposed space mission, which will use coherent laser beams exchanged between three remote spacecraft to detect and study low-frequency cosmic gravitational radiation. In the low-part of its frequency band, the LISA strain sensitivity will be dominated by the incoherent superposition of hundreds of millions of gravitational wave signals radiated by inspiraling white-dwarf binaries present in our own galaxy. In order to estimate the magnitude of the LISA response to this background, we have simulated a synthesized population that recently appeared in the literature. We find the amplitude of the galactic white-dwarf binary background in the LISA data to be modulated in time, reaching a minimum equal to about twice that of the LISA noise for a period of about two months around the time when the Sun-LISA direction is roughly oriented towards the Autumn equinox. Since the galactic white-dwarfs background will be observed by LISA not as a stationary but rather as a cyclostationary random process with a period of one year, we summarize the theory of cyclostationary random processes, present the corresponding generalized spectral method needed to characterize such process, and make a comparison between our analytic results and those obtained by applying our method to the simulated data. We find that, by measuring the generalized spectral components of the white-dwarf background, LISA will be able to infer properties of the distribution of the white-dwarfs binary systems present in our Galaxy.

#### Apr 25, 2005

0504112 (/preprints/gr-qc)
2005-04-25, 11:40 

## [gr-qc/0504108] Displacement- and Timing-Noise Free Gravitational-Wave Detection

Authors: Yanbei Chen, Seiji Kawamura

Date: Fri, 22 Apr 2005

Abstract: Motivated by a recently-invented scheme of displacement-noise-free gravitational-wave detection, we demonstrate the existence of gravitational-wave detection schemes insusceptible to both displacement and timing (laser) noises, and are thus realizable by shot-noise-limited laser interferometry. This is possible due to two reasons: first, gravitational waves and displacement disturbances contribute to light propagation times in different manners; second, for an N-detector system, the number of signal channels is of the order O(Nˆ2), while the total number of timing- and displacement-noise channels is of the order O(N).

#### Apr 25, 2005

0504108 (/preprints/gr-qc)
2005-04-25, 11:40 

## [gr-qc/0504086] Was Einstein Right? Testing Relativity at the Centenary

Authors: Clifford M. Will

Date: Tue, 19 Apr 2005

Abstract: We review the experimental evidence for Einstein's special and general relativity. A variety of high precision null experiments verify the weak equivalence principle and local Lorentz invariance, while gravitational redshift and other clock experiments support local position invariance. Together these results confirm the Einstein Equivalence Principle which underlies the concept that gravitation is synonymous with spacetime geometry, and must be described by a metric theory. Solar system experiments that test the weak-field, post-Newtonian limit of metric theories strongly favor general relativity. The Binary Pulsar provides tests of gravitational-wave damping and of strong-field general relativity. Recently discovered binary pulsar systems may provide additional tests. Future and ongoing experiments, such as the Gravity Probe B Gyroscope Experiment, satellite tests of the Equivalence principle, and tests of gravity at short distance to look for extra spatial dimensions could constrain extensions of general relativity. Laser interferometric gravitational-wave observatories on Earth and in space may provide new tests of gravitational theory via detailed measurements of the properties of gravitational waves.

#### Apr 20, 2005

0504086 (/preprints/gr-qc)
2005-04-20, 11:40 

## [gr-qc/0504085] Special Relativity: A Centenary Perspective

Authors: Clifford M. Will

Date: Tue, 19 Apr 2005

Abstract: This article is a partly pedagogical, partly historical and partly technical review of special relativity and its experimental foundations, in honor of the centenary of Einstein's annus mirabilis.

#### Apr 20, 2005

0504085 (/preprints/gr-qc)
2005-04-20, 11:40 

## [gr-qc/0504082] Constraining nuclear equations of state using gravitational waves from hypermassive neutron stars

Authors: Masaru Shibata

Date: Tue, 19 Apr 2005

Abstract: Latest general relativistic simulations for merger of binary neutron stars with realistic equations of state (EOSs) show that a hypermassive neutron star of an ellipsoidal figure is formed after the merger if the total mass is smaller than a threshold value which depends on the EOSs. The effective amplitude of quasiperiodic gravitational waves from such hypermassive neutron stars is $\sim 6$--$7 \times 10ˆ{-21}$ at a distance of 50 Mpc, which may be large enough for detection by advanced laser interferometric gravitational wave detectors although the frequency is high $\sim 3$ kHz. We point out that the detection of such signal may lead to constraining the EOSs for neutron stars.

#### Apr 20, 2005

0504082 (/preprints/gr-qc)
2005-04-20, 11:39 

## [gr-qc/0504079] Response of the common mode of interferometric detectors to a stochastic background of massive scalar radiation

Authors: N. Bonasia, M. Gasperini

Date: Mon, 18 Apr 2005

Abstract: We compute the angular pattern and the overlap reduction functions for the geodesic and non-geodesic response of the common mode of two interferometers interacting with a stochastic, massive scalar background. We also discuss the possible overlap between common and differential modes. We find that the cross-correlated response of two common modes to a non-relativistic background may be higher than the response of two differential modes to the same background.

#### Apr 19, 2005

0504079 (/preprints/gr-qc)
2005-04-19, 13:28 

## [gr-qc/0504071] Characterizing the Galactic Gravitational Wave Background with LISA

Authors: Seth E. Timpano, Louis J. Rubbo, Neil J. Cornish

Date: Sat, 16 Apr 2005

Abstract: We present a Monte Carlo simulation for the response of the Laser Interferometer Space Antenna (LISA) to the galactic gravitational wave background. The simulated data streams are used to estimate the number and type of binary systems that will be individually resolved. We find that the background is highly non-Gaussian due to the presence of individual bright sources, but once these sources are identified and removed, the remaining signal is Gaussian. We give a new estimate of the confusion noise due to the unresolved sources that differs significantly from earlier estimates.

#### Apr 18, 2005

0504071 (/preprints/gr-qc)
2005-04-18, 12:15 

## [gr-qc/0504065] Report on the first binary black hole inspiral search in LIGO data

Authors: Eirini Messaritaki, for the LIGO Scientific Collaboration

Date: Thu, 14 Apr 2005

Abstract: The LIGO Scientific Collaboration is currently engaged in the first search for binary black hole inspiral signals in real data. We are using the data from the second LIGO science run and we focus on inspiral signals coming from binary systems with component masses between 3 and 20 solar masses. We describe the analysis methods used and report on preliminary estimates for the sensitivities of the LIGO instruments during the second science run.

#### Apr 15, 2005

0504065 (/preprints/gr-qc)
2005-04-15, 11:45 

## [gr-qc/0504062] The LTP Experiment on the LISA Pathfinder Mission

Authors: S. Vitale (for LTP Collaboration)

Date: Thu, 14 Apr 2005

Abstract: We report on the development of the LISA Technology Package (LTP) experiment that will fly on board the LISA Pathfinder mission of the European Space Agency in 2008. We first summarize the science rationale of the experiment aimed at showing the operational feasibility of the so called Transverse-Traceless coordinate frame within the accuracy needed for LISA. We then show briefly the basic features of the instrument and we finally discuss its projected sensitivity and the extrapolation of its results to LISA.

#### Apr 15, 2005

0504062 (/preprints/gr-qc)
2005-04-15, 11:45 

## [gr-qc/0504061] Gravity and the Quantum Vacuum Inertia Hypothesis

Authors: Alfonso Rueda, Bernard Haisch

Date: Fri, 15 Apr 2005

Abstract: In previous work it has been shown that the electromagnetic quantum vacuum, or electromagnetic zero-point field, makes a contribution to the inertial reaction force on an accelerated object. We show that the result for inertial mass can be extended to passive gravitational mass. As a consequence the weak equivalence principle, which equates inertial to passive gravitational mass, appears to be explainable. This in turn leads to a straightforward derivation of the classical Newtonian gravitational force. We call the inertia and gravitation connection with the vacuum fields the quantum vacuum inertia hypothesis. To date only the electromagnetic field has been considered. It remains to extend the hypothesis to the effects of the vacuum fields of the other interactions. We propose an idealized experiment involving a cavity resonator which, in principle, would test the hypothesis for the simple case in which only electromagnetic interactions are involved. This test also suggests a basis for the free parameter $\eta(\nu)$ which we have previously defined to parametrize the interaction between charge and the electromagnetic zero-point field contributing to the inertial mass of a particle or object.

#### Apr 15, 2005

0504061 (/preprints/gr-qc)
2005-04-15, 11:44 

## [gr-qc/0504046] Placement of templates technique in a 2D parameter space for binary inspiral searches

Authors: F. Beauville, D. Buskulic, R. Flaminio, R. Gouaty, D. Grosjean, F. Marion, B. Mours, E. Tournefier, D. Verkindt, M. Yvert

Date: Tue, 12 Apr 2005

Abstract: In the search for binary systems inspiral signal in interferometric gravitational waves detectors, one needs the generation and placement of a grid of templates. We present an original technique for the placement in the associated parameter space, that makes use of the variation of size of the isomatch ellipses in order to reduce the number of templates necessary to cover the parameter space. A study of the covering efficiency, as well as a comparison with a very simple regular tiling using a single ellipse is made.

#### Apr 13, 2005

0504046 (/preprints/gr-qc)
2005-04-13, 11:22 

## [gr-qc/0504042] A time-domain MCMC search and upper limit technique for gravitational waves of uncertain frequency from a targeted neutron star

Authors: John Veitch, Richard Umstaetter, Renate Meyer, Nelson Christensen, Graham Woan

Date: Sat, 9 Apr 2005

Abstract: It is computationally expensive to search the large parameter space associated with a gravitational wave signal of uncertain frequency, such as might be expected from the possible pulsar generated by SN1987A. To address this difficulty we have developed a Markov Chain Monte Carlo method that performs a time-domain Bayesian search for a signal over a 4 Hz frequency band and a spindown of magnitude of up to $1\ee{-9}$ Hz/s. We use Monte Carlo simulations to set upper limits on signal amplitude with this technique, which we intend to apply to a gravitational wave search.

#### Apr 12, 2005

0504042 (/preprints/gr-qc)
2005-04-12, 10:33 

## [lrr-2005-3] Gravitational-Wave Data Analysis: Formalism and Sample Applications: The Gaussian Case

Authors: Piotr Jaranowski, Andrzej Królak

Date: Apr 11, 2005

Abstract: The article reviews the statistical theory of signal detection in application to analysis of deterministic gravitational-wave signals in the noise of a detector. Statistical foundations for the theory of signal detection and parameter estimation are presented. Several tools needed for both theoretical evaluation of the optimal data analysis methods and for their practical implementation are introduced. They include optimal signal-to-noise ratio, Fisher matrix, false alarm and detection probabilities, F-statistic, template placement, and fitting factor. These tools apply to the case of signals buried in a stationary and Gaussian noise. Algorithms to efficiently implement the optimal data analysis techniques are discussed. Formulas are given for a general gravitational-wave signal that includes as special cases most of the deterministic signals of interest.

#### Apr 11, 2005

lrr-2005-3 (/preprints)
2005-04-11, 10:05 

## [astro-ph/0504048] Search templates for stochastic gravitational-wave backgrounds

Authors: Sukanta Bose

Date: Sat, 2 Apr 2005

Abstract: Several earth-based gravitational-wave (GW) detectors are actively pursuing the quest for placing observational constraints on models that predict the behavior of a variety of astrophysical and cosmological sources. These sources span a wide gamut, ranging from hydrodynamic instabilities in neutron stars (such as r-modes) to particle production in the early universe. Signals from a subset of these sources are expected to appear in these detectors as stochastic GW backgrounds (SGWBs). The detection of these backgrounds will help us in characterizing their sources. Accounting for such a background will also be required by some detectors, such as the proposed space-based detector LISA, so that they can detect other GW signals. Here, we formulate the problem of constructing a bank of search templates that discretely span the parameter space of a generic SGWB. We apply it to the specific case of a class of cosmological SGWBs, known as the broken power-law models. We derive how the template density varies in their three-dimensional parameter space and show that for the LIGO 4km detector pair, with LIGO-I sensitivities, about a few hundred templates will suffice to detect such a background while incurring a loss in signal-to-noise ratio of no more than 3%.

#### Apr 08, 2005

0504048 (/preprints/astro-ph)
2005-04-08, 12:44 

## [gr-qc/0504026] Simulation of the White Dwarf -- White Dwarf galactic background in the LISA data

Authors: Jeffrey A. Edlund, Massimo Tinto, Andrzej Królak, Gijs Nelemans

Date: Thu, 7 Apr 2005

Abstract: LISA (Laser Interferometer Space Antenna) is a proposed space mission, which will use coherent laser beams exchanged between three remote spacecraft to detect and study low-frequency cosmic gravitational radiation. In the low-part of its frequency band, the LISA strain sensitivity will be dominated by the incoherent superposition of hundreds of millions of gravitational wave signals radiated by inspiraling white-dwarf binaries present in our own galaxy. In order to estimate the magnitude of the LISA response to this background, we have simulated a synthesized population that recently appeared in the literature. We find the amplitude of the galactic white-dwarf binary background in the LISA data to be modulated in time, reaching a minimum equal to about twice that of the LISA noise for a period of about two months around the time when the Sun-LISA direction is roughly oriented towards the Autumn equinox. Since the galactic white-dwarfs background will be observed by LISA not as a stationary but rather as a cyclostationary random process with a period of one year, we summarize the theory of cyclostationary random processes and present the corresponding generalized spectral method needed to characterize such process. We find that, by measuring the generalized spectral components of the white-dwarf background, LISA will be able to infer properties of the distribution of the white-dwarfs binary systems present in our Galaxy.

#### Apr 08, 2005

0504026 (/preprints/gr-qc)
2005-04-08, 12:43 

## [gr-qc/0504017] Testing general relativity and probing the merger history of massive black holes with LISA

Authors: Emanuele Berti, Alessandra Buonanno, Clifford M. Will

Date: Tue, 5 Apr 2005

Abstract: We study parameter estimation for inspiralling compact binaries of massive black holes (MBH), and for inspirals of neutron stars into intermediate-mass black holes, using LISA. We include non-precessional spin effects. We work both in Einstein's theory and in alternative theories of gravity of the scalar-tensor and massive-graviton types. Inclusion of spin terms in MBH binaries has little effect on the angular resolution or on distance determination accuracy, but it degrades the estimation of intrinsic binary parameters such as chirp mass and reduced mass by between one and two orders of magnitude. The bound on the coupling parameter of scalar-tensor gravity is significantly reduced by the presence of spin couplings, while the reduction in the graviton-mass bound is milder. LISA will measure the luminosity distance of MBHs to better than ~10% out to z~4 for a (10ˆ6+10ˆ6) Msun binary, and out to z~2 for a (10ˆ7+10ˆ7) Msun binary. The chirp mass of a MBH binary can always be determined with excellent accuracy. Ignoring spin effects, the reduced mass can be measured within ~1% out to z=10 and beyond for a (10ˆ6+10ˆ6) Msun binary, but only out to z~2 for a (10ˆ7+10ˆ7) Msun binary. Present-day MBH coalescence rate calculations indicate that most detectable events should originate at z~2-6: at these redshifts LISA can be used to measure the two black hole masses and their luminosity distance with sufficient accuracy to probe the merger history of MBHs. If the low-frequency LISA noise can only be trusted down to 10ˆ-4 Hz, parameter estimation for MBHs (and LISA's ability to perform reliable cosmological observations) will be significantly degraded.

#### Apr 05, 2005

0504017 (/preprints/gr-qc)
2005-04-05, 22:57 

## [gr-qc/0504015] Gravitational radiation reaction and inspiral waveforms in the adiabatic limit

Authors: Scott A. Hughes, Steve Drasco, Eanna E. Flanagan, Joel Franklin

Date: Tue, 5 Apr 2005

Abstract: We describe progress evolving an important limit of binary orbits in general relativity, that of a stellar mass compact object gradually spiraling into a much larger, massive black hole. These systems are of great interest for gravitational wave observations. We have developed tools to compute for the first time the radiated fluxes of energy and angular momentum, as well as instantaneous snapshot waveforms, for generic geodesic orbits. For special classes of orbits, we compute the orbital evolution and waveforms for the complete inspiral by imposing global conservation of energy and angular momentum. For fully generic orbits, inspirals and waveforms can be obtained by augmenting our approach with a prescription for the self force in the adiabatic limit derived by Mino. The resulting waveforms should be sufficiently accurate to be used in future gravitational-wave searches.

#### Apr 05, 2005

0504015 (/preprints/gr-qc)
2005-04-05, 22:57 

## [gr-qc/0504011] The generalized F-statistic: multiple detectors and multiple GW pulsars

Authors: Curt Cutler, Bernard F. Schutz

Date: Mon, 4 Apr 2005

Abstract: The F-statistic, derived by Jaranowski, Krolak & Schutz (1998), is the optimal (frequentist) statistic for the detection of nearly periodic gravitational waves from known neutron stars, in the presence of stationary, Gaussian detector noise. The F-statistic was originally derived for the case of a single detector, whose noise spectral density was assumed constant in time, and for a single known neutron star. Here we show how the F-statistic can be straightforwardly generalized to the cases of 1) a network of detectors with time-varying noise curves, and 2) a population of known sources. Fortunately, all the important ingredients that go into our generalized F-statistics are already calculated in the single-source/single-detector searches that are currently implemented, e.g., in the LIGO Software Library, so implementation of optimal multi-detector, multi-source searches should require negligible additional cost in computational power or software development.

#### Apr 05, 2005

0504011 (/preprints/gr-qc)
2005-04-05, 13:52 

## [gr-qc/0504006] Global parameter-space correlations of coherent searches for continuous gravitational waves

Authors: Reinhard Prix, Yousuke Itoh

Date: Fri, 1 Apr 2005

Abstract: The space of phase-parameters (sky-position, frequency, spindowns) of a coherent matched-filtering search for continuous gravitational waves from isolated neutron stars shows strong global correlations (‘circles in the sky’). In the local limit this can be analysed in terms of a parameter-space metric, but the global properties are less well studied. In this work we report on our recent progress in understanding these global correlations analytically for short to intermediate (less than a month, say) observation times and neglecting spindowns. The location of these correlation-circles in parameter-space is found to be determined mostly by the orbital velocity of the earth, while the spin-motion of the detector and the antenna-patterns only contribute significantly to the amplitude of the detection statistic along these circles.

#### Apr 05, 2005

0504006 (/preprints/gr-qc)
2005-04-05, 13:52 

## [gr-qc/0504012] Detecting Galactic Binaries with LISA

Authors: Neil J. Cornish, Edward K. Porter

Date: Mon, 4 Apr 2005

Abstract: One of the main sources of gravitational waves for the LISA space-borne interferometer are galactic binary systems. The waveforms for these sources are represented by eight parameters, of which four are extrinsic, and four are intrinsic to the system. Geometrically, these signals exist in an 8-d parameter space. By calculating the metric tensor on this space, we calculate the number of templates needed to search for such sources. We show in this study that below a particular monochromatic frequency, we can ignore one of the intrinsic parameters and search over a 7-d space. Beyond this frequency, we have a sudden change in dimensionality of the parameter space from 7 to 8 dimensions, which results in a change in the scaling of the growth of template number as a function of monochromatic frequency.

#### Apr 05, 2005

0504012 (/preprints/gr-qc)
2005-04-05, 13:52 

## [astro-ph/0503511] Testing models of supermassive black hole seed formation through gravity waves

Authors: Savvas M. Koushiappas (1), Andrew R. Zentner (2) ((1) ETH, (2) KICP, UChicago)

Date: Wed, 30 Mar 2005

Abstract: We study the gravitational wave background produced from the formation and assembly of supermassive black holes within the cosmological paradigm of hierarchical structure formation. In particular, we focus on a supermassive black hole formation scenario in which the present-day population of supermassive black holes is built from high-mass seed black holes and we compute the concomitant spectrum of gravitational radiation produced by mergers of the seed black holes. We find that this scenario predicts a large, stochastic gravitational wave background that should be observable at very high signal-to-noise with the proposed Laser Interferometric Space Antenna (LISA). This prediction is robust and insensitive to several of the details of the model. We conclude that the LISA interferometer will be able to effectively rule out or confirm a class of models where supermassive black holes grow from high-mass seed black holes and may be able to place strong limits on the role of mergers as a channel for supermassive black hole growth. Supermassive black hole seeds likely form in the earliest proto-galactic structures at high redshift and the masses of supermassive black holes are known to be strongly correlated with the potentials of the spheroids in which they reside, therefore these results imply that LISA can be used as a powerful probe of the physics of galaxy formation and proto-galaxy formation at very high redshift.

#### Apr 01, 2005

0503511 (/preprints/astro-ph)
2005-04-01, 09:39