The dipole of the astrophysical gravitational-wave background

Dall'Armi, Lorenzo Valbusa; Ricciardone, Angelo; Bertacca, Daniele

doi:10.1088/1475-7516/2022/11/040

Cited by 16 publications

(14 citation statements)

References 137 publications

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“…However, in the context of thirdgeneration interferometers, it is expected that many of the binaries which make up this "stochastic" signal will in fact be individually resolvable, allowing us to coherently subtract them and search for underlying cosmological signals [72,73], to which our dipole search can be applied. Alternatively, it may be possible to mitigate the effects of shot noise by optimally combining data from different time segments [32] and frequency bins [35]. We leave a fuller exploration of these issues for future work.…”

Section: Discussionmentioning

confidence: 99%

“…Aside from the intrinsic anisotropies, there are also extrinsic or kinematic anisotropies due to the peculiar motion of our GW detectors with respect to the rest frame of the GWB [20,23,[33][34][35]. Most notable of these is the Doppler enhancement of the GW intensity we observe from sources we are moving toward and the corresponding reduction in intensity from sources we are receding from.…”

Section: Introductionmentioning

confidence: 99%

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Targeted search for the kinematic dipole of the gravitational-wave background

et al. 2022

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There is growing interest in using current and future gravitational-wave interferometers to search for anisotropies in the gravitational-wave background. One guaranteed anisotropic signal is the kinematic dipole induced by our peculiar motion with respect to the cosmic rest frame, as measured in other full-sky observables such as the cosmic microwave background. Our prior knowledge of the amplitude and direction of this dipole is not explicitly accounted for in existing searches by LIGO/Virgo/KAGRA but could provide crucial information to help disentangle the sources which contribute to the gravitationalwave background. Here, we develop a targeted search pipeline which uses this prior knowledge to enable unbiased and minimum-variance inference of the dipole magnitude. Our search generalizes existing methods to allow for a time-dependent signal model, which captures the annual modulation of the dipole due to the Earth's orbit. We validate our pipeline on mock data, demonstrating that neglecting this time dependence can bias the inferred dipole by as much as Oð10%Þ. We then run our analysis on the full LIGO/Virgo O1 þ O2 þ O3 dataset, obtaining upper limits on the dipole amplitude that are consistent with existing anisotropic search results.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Targeted search for the kinematic dipole of the gravitational-wave background

et al. 2022

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“…refs. [137][138][139][140][141][142][143][144][145][146][147][148][149][150][151]. Of specific interest is the recent code [152] that compute anisotropies of the AGWB.…”

Section: Agwbmentioning

confidence: 99%

Probing parity-odd bispectra with anisotropies of GW V modes

Orlando

2022

J. Cosmol. Astropart. Phys.

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It is well known that non-trivial squeezed tensor bispectra can lead to anisotropies in the inflationary stochastic gravitational wave (GW) background, providing us with an alternative and complementary window to primordial non-Gaussianities (NGs) with respect to the CMB. Previous works have highlighted the detection prospects of parity-even tensor NGs via the GW I-mode anisotropies. In this work we extend this by analysing for the first time the additional information carried by GW V-mode anisotropies due to squeezed NGs. We show that GW V modes allow us to probe parity-odd squeezed 〈 tts 〉 and 〈 ttt 〉 bispectra. These bispectra break parity at the non-linear level and can be introduced by allowing alternative symmetry breaking patterns during inflation, like those comprised in solid inflation. Considering a BBO-like experiment, we find that a non-zero detection of squeezed 〈 tts 〉 parity-odd bispectra in the V modes dipole is possible without requiring any short-scale enhancement of the GW power spectrum amplitude over the constraints set by the CMB. We also briefly discuss the role of V-CMB cross-correlations. Our work can be extended in several directions and motivates a systematic search for polarized GW anisotropies in the next generations of GW experiments.

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“…But, as for the CMB, it is potentially well larger than intrinsic cosmological anisotropies (see, e.g., the studies [34][35][36][37][38][39][40]). Kinematic anisotropies is a topic of active research in the context of GW interferometers [23,[41][42][43][44][45]. It is then worth asking what information we can obtain from a possible future detection of kinematic anisotropies with PTA experiments.…”

Section: Introductionmentioning

confidence: 99%

Kinematic anisotropies and pulsar timing arrays

Tasinato

2023

Phys. Rev. D

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Doppler anisotropies, induced by our relative motion with respect to the source rest frame, are a guaranteed property of stochastic gravitational wave backgrounds of cosmological origin. If detected by future pulsar timing array measurements, they will provide interesting information on the physics sourcing gravitational waves, which is hard or even impossible to extract from measurements of the isotropic part of the background only. We analytically determine the pulsar response function to kinematic anisotropies, including possible effects due to parity violation, to features in the frequency dependence of the isotropic part of the spectrum, as well as to the presence of extra scalar and vector polarizations. For the first time, we show how the sensitivity to different effects crucially depends on the pulsar configuration with respect to the relative motion among frames. Correspondingly, we propose examples of strategies of detection, each aimed at exploiting future measurements of kinematic anisotropies for characterizing distinct features of the cosmological gravitational wave background.

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The dipole of the astrophysical gravitational-wave background

Cited by 16 publications

References 137 publications

Targeted search for the kinematic dipole of the gravitational-wave background

Targeted search for the kinematic dipole of the gravitational-wave background

Probing parity-odd bispectra with anisotropies of GW V modes

Kinematic anisotropies and pulsar timing arrays

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