Uncovering gravitational-wave backgrounds from noises of unknown shape with LISA

Baghi, Quentin; Karnesis, Nikolaos; Bayle, Jean-Baptiste; Besançon, M.; Inchauspé, H.

doi:10.1088/1475-7516/2023/04/066

Cited by 12 publications

(6 citation statements)

References 86 publications

(96 reference statements)

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“…For any particular ( Ũ , Ṽ ) combination, the coefficients c U ij (f ) and c V ij (f ) can be combined to form a 6 × 6 matrix 9 C U V . We remark that this procedure is similar to what has very recently (and independently from our work) been proposed in [38]. Note that the coefficient matrices C U V depend only on the choice of TDI variables, while the actual noise or signal correlations are encoded in the previously computed single-link correlation matrix S η .…”

Section: Signal and Noise Projection On The Tdi Variablesmentioning

confidence: 59%

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Stochastic gravitational wave background reconstruction for a non-equilateral and unequal-noise LISA constellation

Hartwig¹,

Lilley²,

Muratore³

et al. 2023

Preprint

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We explore the impact of choosing different sets of Time-Delay Interferometry (TDI) variables for detecting and reconstructing Stochastic Gravitational Wave Background (SGWB) signals and estimating the instrumental noise in LISA. Most works in the literature build their data analysis pipelines relying on a particular set of TDI channels, the so-called AET variables, which are orthogonal under idealized conditions. By relaxing the assumption of a perfectly equilateral LISA configuration, we investigate to which degree these channels remain orthogonal and compare them to other TDI channels. We show that different sets of TDI variables are more robust under perturbations of the perfect equilateral configuration, better preserving their orthogonality and, thus, leading to a more accurate estimate of the instrumental noise. Moreover, we investigate the impact of considering the noise levels associated with each instrumental noise source to be independent of one another, generalizing the analysis from two to twelve noise parameters. We find that, in this scenario, the assumption of orthogonality is broken for all the TDI variables, leading to a misestimation of measurement error for some of the noise parameters. Remarkably, we find that for a flat power-law signal, the reconstruction of the signal parameters is nearly unaffected in these various configurations.

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Section: Signal and Noise Projection On The Tdi Variablesmentioning

confidence: 59%

“…Future studies are needed in order to test the impact of these effects on noise and signal reconstruction. For existing works setting the path in this direction, see, e.g., [38,42,43].…”

Section: Discussionmentioning

confidence: 99%

Stochastic gravitational wave background reconstruction for a non-equilateral and unequal-noise LISA constellation

Hartwig¹,

Lilley²,

Muratore³

et al. 2023

Preprint

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“…Similar approaches for stochastic signals in simulated LISA [78] data have been discussed in, e.g. [4,79,80]. In addition, some gravitational wave detectors (e.g.…”

Section: Scalar-induced Sgwb Phenomenologymentioning

confidence: 84%

Primordial stochastic gravitational wave backgrounds from a sharp feature in three-field inflation. Part I. The radiation era

Aragam,

Paban,

Rosati

2023

J. Cosmol. Astropart. Phys.

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The detection of a primordial stochastic gravitational wave background has the potential to reveal unprecedented insights into the early universe, and possibly into the dynamics of inflation. Generically, UV-complete inflationary models predict an abundance of light scalars, so any inflationary stochastic background may well be formed in a model with several interacting degrees of freedom. The stochastic backgrounds possible from two-field inflation have been well-studied in the literature, but it is unclear how similar they are to the possibilities from many-field inflation. In this work we study stochastic backgrounds from more-than-two field inflation for the first time, focusing on the scalar-induced background produced during the radiation era by a brief turn in three-field space. We find an analytic expression for the enhancement in the power spectrum as a function of the turn rate and the torsion, and show that unique signatures of three-field dynamics are possible in the primordial power spectrum and gravitational wave spectrum. We confirm our analytic results with a suite of numerical simulations and find good agreement in the shape and amplitude of the power spectra. We also comment on the detection prospects in LISA and other future detectors. We do not expect the moderately large growth of the inflationary perturbations necessary for detection to cause a breakdown of perturbation theory, but this must be verified on a case-by-case basis for specific microphysical models to make a definitive claim.

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“…Existing work has focused on distinguishing between several components of SGWB, but primarily focusing on the isotropic component [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] (see also [49,50] for ideas utilizing the time-dependence of an SGWB). An important feature that has been used so far is that the astrophysical and cosmological components typically have different frequency dependencies.…”

Section: Introductionmentioning

confidence: 99%

Unraveling cosmological anisotropies within stochastic gravitational wave backgrounds

Cui,

Kumar,

Sundrum

et al. 2023

J. Cosmol. Astropart. Phys.

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Identifying the anisotropies in a cosmologically sourced stochastic gravitational wave background (SGWB) would be of significance in shedding light on the nature of primordial inhomogeneities. For example, if SGWB carries isocurvature fluctuations, it would provide evidence for a multi-field inflationary origin of these inhomogeneities. However, this is challenging in practice due to finite detector sensitivity and also the presence of the astrophysical foregrounds that can compete with the cosmological signal. In this work, we explore the prospects for measuring cosmological SGWB anisotropies in the presence of an astrophysical counterpart and detector noise. To illustrate the main idea, we perform a Fisher analysis using a well-motivated cosmological SGWB template corresponding to a first order phase transition, and an astrophysical SGWB template corresponding to extra-galactic binary mergers, and compute the uncertainty with which various parameters characterizing the isotropic and anisotropic components can be extracted. We also discuss some subtleties and caveats involving shot noise in the astrophysical foreground. Overall, we show that upcoming experiments, e.g., LISA, Taiji, Einstein Telescope, Cosmic Explorer, and BBO, can all be effective in discovering plausible anisotropic cosmological SGWBs.

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Uncovering gravitational-wave backgrounds from noises of unknown shape with LISA

Cited by 12 publications

References 86 publications

Stochastic gravitational wave background reconstruction for a non-equilateral and unequal-noise LISA constellation

Stochastic gravitational wave background reconstruction for a non-equilateral and unequal-noise LISA constellation

Primordial stochastic gravitational wave backgrounds from a sharp feature in three-field inflation. Part I. The radiation era

Unraveling cosmological anisotropies within stochastic gravitational wave backgrounds

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