Search for a stochastic gravitational-wave background using a pair of torsion-bar antennas

Shoda, A.; Ando, Masaki; Ishidoshiro, K.; Okada, Kenshi; Kokuyama, Wataru; Aso, Y.; Tsubono, K.

doi:10.1103/physrevd.89.027101

Cited by 27 publications

(31 citation statements)

References 17 publications

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“…Torsion-bar sensitivities have surpassed 10 −7 Hz −1/2 at 0.1 Hz (Shoda et al 2014). Naturally, work on detector designs needs to be accompanied by careful selection of instrument sites, which can have a big impact on ambient seismic or infrasound fields (Berger et al 2004;Brown et al 2014), and also on the associated gravity noise.…”

Section: Downloaded Frommentioning

confidence: 99%

“…Furthermore, future ground-based detectors have been proposed, such as the Einstein Telescope (ET Science Team 2011) with even more enhanced strain sensitivity, and a detection band extending down to a few Hz. In parallel to these kilometre-scale detectors, groups are developing gravity strainmeters targeting signals below 1 Hz, which are better suited to detect gravity perturbations changing over timescales of a few seconds (Ando et al 2010;Hohensee et al 2011;Dickerson et al 2013;Shoda et al 2014).…”

Section: Motivationsmentioning

confidence: 99%

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Transient gravity perturbations induced by earthquake rupture

Harms

Ampuero

Barsuglia

et al. 2015

Geophysical Journal International

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S U M M A R YThe static and transient deformations produced by earthquakes cause density perturbations which, in turn, generate immediate, long-range perturbations of the Earth's gravity field. Here, an analytical solution is derived for gravity perturbations produced by a point double-couple source in homogeneous, infinite, non-self-gravitating elastic media. The solution features transient gravity perturbations that occur at any distance from the source between the rupture onset time and the arrival time of seismic P waves, which are of potential interest for real-time earthquake source studies and early warning. An analytical solution for such prompt gravity perturbations is presented in compact form. We show that it approximates adequately the prompt gravity perturbations generated by strike-slip and dip-slip finite fault ruptures in a half-space obtained by numerical simulations based on the spectral element method. Based on the analytical solution, we estimate that the observability of prompt gravity perturbations within 10 s after rupture onset by current instruments is severely challenged by the background microseism noise but may be achieved by high-precision gravity strainmeters currently under development. Our analytical results facilitate parametric studies of the expected prompt gravity signals that could be recorded by gravity strainmeters.

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Section: Downloaded Frommentioning

confidence: 99%

Section: Motivationsmentioning

confidence: 99%

Transient gravity perturbations induced by earthquake rupture

Harms

Ampuero

Barsuglia

et al. 2015

Geophysical Journal International

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“…The spectral index of the primordial GW spectrum can change at some frequency. Therefore, #1 There are more ways to obtain upper bounds on the amount of the stochastic GWs, such as dark radiation constraints from the CMB [28,29], CMB µ distortion [30,31], helioseismology [32], precision Doppler tracking from the Cassini spacecraft [33], orbital monitoring of binary systems [34], torsion-bar antennas [35], seismic spectrum from the Earth [36], synchronous recycling interferometers [37], crosscorrelation measurement between the Explorer and Nautilus cryogenic resonant bar detectors [38], and Global Positioning System (GPS) satellite [39].…”

Section: Introductionmentioning

confidence: 99%

Blue-tilted tensor spectrum and thermal history of the Universe

Kuroyanagi

Takahashi

Yokoyama

2015

J. Cosmol. Astropart. Phys.

110

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We investigate constraints on the spectral index of primordial gravitational waves (GWs), paying particular attention to a blue-tilted spectrum. Such constraints can be used to test a certain class of models of the early Universe. We investigate observational bounds from LIGO+Virgo, pulsar timing and big bang nucleosynthesis, taking into account the suppression of the amplitude at high frequencies due to reheating after inflation and also late-time entropy production. Constraints on the spectral index are presented by changing values of parameters such as reheating temperatures and the amount of entropy produced at late time. We also consider constraints under the general modeling approach which can approximately describe various scenarios of the early Universe. We show that the constraints on the blue spectral tilt strongly depend on the underlying assumption and, in some cases, a highly blue-tilted spectrum can still be allowed.

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“…First of all, the direct detection of GWs will be a milestone in science opening a new window to our universe, and marking the beginning of a new era in observational astronomy. Second, several groups around the world have already started to adapt the technology to novel interferometer concepts [60, 155], with potential applications not only in GW science, but also geophysics. The basic measurement scheme is always the same: the relative displacement of test masses is monitored by using ultra-stable lasers.…”

Section: Introductionmentioning

confidence: 99%

Terrestrial Gravity Fluctuations

Harms

2015

Living Rev Relativ

139

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Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10−23 Hz−1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of terrestrial gravity fluctuations will have great impact on the future development of GW detectors and high-precision gravimetry in general, and many open questions need to be answered still as emphasized in this article.

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Search for a stochastic gravitational-wave background using a pair of torsion-bar antennas

Cited by 27 publications

References 17 publications

Transient gravity perturbations induced by earthquake rupture

Transient gravity perturbations induced by earthquake rupture

Blue-tilted tensor spectrum and thermal history of the Universe

Terrestrial Gravity Fluctuations

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