pith. sign in

arxiv: 2504.07063 · v3 · submitted 2025-04-09 · 🌌 astro-ph.CO · gr-qc

Non-Gaussianity of Tensor Induced Density Perturbations

Pith reviewed 2026-05-22 19:56 UTC · model grok-4.3

classification 🌌 astro-ph.CO gr-qc
keywords non-Gaussianityprimordial gravitational wavestensor-induced perturbationsbispectrumdensity contrastgalaxy surveyschi-squared distribution
0
0 comments X

The pith

Tensor-induced density perturbations from primordial gravitational waves exhibit non-Gaussianity whose bispectrum shape depends on the underlying GW spectrum.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper shows that primordial gravitational waves induce second-order matter density perturbations through local fluctuations in their energy density. These perturbations follow a chi-squared distribution, naturally producing significant non-Gaussianity. The authors compute the bispectrum for different primordial GW power spectra and find that its shape is sensitive to the spectrum by construction. Gaussian-bump and monochromatic sources in particular produce a strong equilateral peak, similar to scalar-induced tensor modes. This non-Gaussian signature offers a new way to probe primordial GWs through galaxy surveys, even though the perturbations otherwise mimic linear ones on sub-horizon scales.

Core claim

The second-order matter density contrast induced by primordial gravitational waves arises from the quadratic term in the tensor energy density and follows a chi-squared distribution, leading to significant non-Gaussianity. The bispectrum of these tensor-induced scalar modes is inherently sensitive to the underlying GWs spectrum, with Gaussian-bump and monochromatic sources producing a strong signal peaking in the equilateral configuration.

What carries the argument

The quadratic dependence of GW energy density on tensor perturbations, which sources the second-order density contrast and produces its chi-squared distribution whose bispectrum encodes the GW spectrum shape.

If this is right

  • Galaxy surveys can detect the non-Gaussianity as a distinct signature of primordial GWs.
  • The equilateral bispectrum peak for bump-like and monochromatic GW spectra provides a way to distinguish different primordial sources.
  • Tensor-induced density perturbations offer a probe of GWs that is complementary to direct detection or scalar-induced effects.
  • The chi-squared nature of the density field implies observable higher-order correlations beyond the bispectrum.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Large-scale structure data from future surveys could be used to place new constraints on the amplitude and tilt of primordial GW spectra.
  • This non-Gaussianity might contribute to scale-dependent bias signals in galaxy clustering, affecting cosmological parameter inference.
  • The mechanism suggests that other second-order induced perturbations could carry similar spectrum-dependent non-Gaussian features.

Load-bearing premise

The second-order matter density contrast is sourced solely by the quadratic term in the tensor energy density, with higher-order scalar and vector contributions remaining negligible on the relevant scales.

What would settle it

A null detection of the predicted equilateral bispectrum peak in galaxy clustering statistics on scales where monochromatic or Gaussian-bump GW sources are expected would contradict the claimed sensitivity of the bispectrum to the GW spectrum.

Figures

Figures reproduced from arXiv: 2504.07063 by Angelo Ricciardone, Mariam Abdelaziz, Pritha Bari, Sabino Matarrese.

Figure 1
Figure 1. Figure 1: The geometrical configuration of the chosen contraction, a modified version of the figure [PITH_FULL_IMAGE:figures/full_fig_p008_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Normalized shapes for the bispectrum of the matter density contrast by scale invariant [PITH_FULL_IMAGE:figures/full_fig_p010_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Normalized shape for the bispectrum of the matter density contrast by a monochromatic [PITH_FULL_IMAGE:figures/full_fig_p011_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Normalized shapes for the bispectrum of the matter density contrast by a Gaussian [PITH_FULL_IMAGE:figures/full_fig_p012_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Impact of different GW sources on the matter power-spectrum; Blue-tilted: ( [PITH_FULL_IMAGE:figures/full_fig_p015_5.png] view at source ↗
read the original abstract

We investigate the non-Gaussianity of second-order matter density perturbations induced by primordial gravitational waves (GWs). These tensor-induced scalar modes arise from local fluctuations in the GWs energy density, which is quadratic in tensor perturbations. The resulting second-order density contrast follows a chi-squared distribution, naturally exhibiting significant non-Gaussianity. We compute the bispectrum of these tensor-induced scalar modes and analyze its dependence on various primordial GWs power spectra, including scale-invariant, blue-tilted, Gaussian-bump, and monochromatic sources. We find that the bispectrum shape is inherently sensitive to the underlying GWs spectrum by construction. In particular, Gaussian-bump and monochromatic sources produce a strong signal peaking in the equilateral configuration, similar to the effect of scalar-induced tensor modes. Our findings reveal a new way to probe primordial GWs via galaxy surveys and highlight a unique feature of tensor-induced density perturbations, otherwise mimicking linear ones on sub-horizon scales.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

1 major / 2 minor

Summary. The paper claims that second-order matter density perturbations induced by primordial gravitational waves exhibit significant non-Gaussianity because the GW energy density is quadratic in the tensor perturbations, yielding a chi-squared distribution for the density contrast. The authors compute the bispectrum of these tensor-induced scalar modes for several primordial GW power spectra (scale-invariant, blue-tilted, Gaussian-bump, and monochromatic) and report that the bispectrum shape is sensitive to the underlying spectrum, with Gaussian-bump and monochromatic sources producing a strong equilateral peak similar to scalar-induced tensor modes. This is presented as a new probe of primordial GWs via galaxy surveys.

Significance. If the central results hold, the work supplies an explicit, spectrum-dependent mapping from primordial tensor power spectra to the bispectrum of induced density perturbations, offering a potentially falsifiable signature for large-scale structure observations that is otherwise degenerate with linear modes on sub-horizon scales. The direct integration over the tensor power spectrum using standard second-order kernels is a clear strength.

major comments (1)
  1. [§3 (formalism and kernel)] The derivation of the second-order density contrast assumes it arises solely from the quadratic term in the tensor energy density with higher-order scalar and vector contributions negligible. This assumption is load-bearing for the claimed equilateral peaking in the Gaussian-bump and monochromatic cases (see the bispectrum results), yet no quantitative estimate of the neglected terms is provided for localized spectra where they could be comparable on sub-horizon scales and alter both amplitude and configuration dependence.
minor comments (2)
  1. [Figures 3-5] Figure captions and axis labels for the bispectrum plots could more explicitly state the normalization and the range of wavenumbers used.
  2. [§6] A short paragraph comparing the predicted bispectrum amplitude to expected noise levels in upcoming surveys (e.g., Euclid or LSST) would improve the observational discussion.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their thorough review and constructive feedback on our manuscript. The major comment raises an important point about the assumptions underlying our derivation, and we address it directly below. We maintain that the leading-order quadratic contribution is the appropriate focus for this work, but we agree that additional justification will improve clarity.

read point-by-point responses
  1. Referee: The derivation of the second-order density contrast assumes it arises solely from the quadratic term in the tensor energy density with higher-order scalar and vector contributions negligible. This assumption is load-bearing for the claimed equilateral peaking in the Gaussian-bump and monochromatic cases (see the bispectrum results), yet no quantitative estimate of the neglected terms is provided for localized spectra where they could be comparable on sub-horizon scales and alter both amplitude and configuration dependence.

    Authors: We agree that the second-order density contrast is derived from the quadratic tensor energy density term, following the standard approach in the literature on induced gravitational perturbations. Higher-order scalar and vector contributions enter at higher orders in the perturbative expansion and are suppressed by additional factors of the small tensor amplitude. For the localized spectra considered, the bispectrum shape is determined by the convolution structure of the quadratic term, which produces the equilateral peak by construction. Nevertheless, we acknowledge that an explicit order-of-magnitude estimate for sub-horizon scales would strengthen the presentation. In the revised version we will add a brief discussion in §3 providing such an estimate, demonstrating that the neglected terms remain subdominant (by at least an order of magnitude) for the amplitudes and wavenumbers relevant to the Gaussian-bump and monochromatic cases, without altering the reported configuration dependence. revision: yes

Circularity Check

0 steps flagged

No significant circularity; bispectrum follows from standard second-order kernels applied to arbitrary tensor spectra.

full rationale

The central derivation integrates the tensor power spectrum against fixed second-order perturbation kernels to obtain the bispectrum; this is a direct computation whose shape dependence on the input spectrum (scale-invariant, bump, monochromatic) is a mathematical consequence of the quadratic energy-density source, not a redefinition or fit. No load-bearing self-citation, no parameter fitted to the target observable, and no uniqueness theorem imported from prior work by the same authors. The stated assumption that higher-order scalar/vector terms are negligible is an explicit approximation, not a hidden tautology that forces the reported equilateral peak.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 0 invented entities

The claim rests on standard second-order cosmological perturbation theory in an FLRW background and the quadratic form of the gravitational-wave energy-momentum tensor. No new particles or forces are postulated.

free parameters (1)
  • overall amplitude of primordial tensor spectrum
    The normalization of the tensor power spectrum sets the absolute strength of the induced density bispectrum and is treated as an input parameter.
axioms (2)
  • standard math Second-order cosmological perturbation theory on an expanding FLRW background
    Invoked to derive the sourcing of scalar density modes by tensor energy density.
  • domain assumption Primordial tensor perturbations are Gaussian
    Required for the quadratic term to produce a chi-squared density contrast.

pith-pipeline@v0.9.0 · 5701 in / 1364 out tokens · 85534 ms · 2026-05-22T19:56:32.472126+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Forward citations

Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Tracing Primordial Gravitational Waves via non-Gaussian Signatures of Halo Bias

    astro-ph.CO 2026-05 unverdicted novelty 7.0

    Tensor-induced non-Gaussianity from primordial gravitational waves generates a unique scale-dependent halo bias correction that can reach order-one amplitude for rare high-redshift halos at z=7.

  2. Primordial Black Hole from Tensor-induced Density Fluctuation: First-order Phase Transitions and Domain Walls

    astro-ph.CO 2026-05 unverdicted novelty 6.0

    Tensor perturbations from first-order phase transitions and domain wall annihilation induce curvature fluctuations at second order that form primordial black holes, allowing asteroid-mass PBHs to comprise all dark mat...

Reference graph

Works this paper leans on

85 extracted references · 85 canonical work pages · cited by 2 Pith papers

  1. [1]

    The Inflationary Universe: A Possible Solution to the Horizon and Flatness Problems,

    A. H. Guth, “The Inflationary Universe: A Possible Solution to the Horizon and Flatness Problems,” Phys. Rev. D , vol. 23, pp. 347–356, 1981

  2. [2]

    BICEP2 / Keck Array x: Constraints on Primordial Gravitational Waves using Planck, WMAP, and New BICEP2/Keck Observations through the 2015 Season,

    P. A. R. Ade et al., “BICEP2 / Keck Array x: Constraints on Primordial Gravitational Waves using Planck, WMAP, and New BICEP2/Keck Observations through the 2015 Season,”Phys. Rev. Lett., vol. 121, p. 221301, 2018

  3. [3]

    A Probe of primordial gravity waves and vorticity,

    M. Kamionkowski, A. Kosowsky, and A. Stebbins, “A Probe of primordial gravity waves and vorticity,” Phys. Rev. Lett. , vol. 78, pp. 2058–2061, 1997

  4. [4]

    Signature of gravity waves in polarization of the microwave background,

    U. Seljak and M. Zaldarriaga, “Signature of gravity waves in polarization of the microwave background,” Phys. Rev. Lett. , vol. 78, pp. 2054–2057, 1997

  5. [5]

    A New Type of Isotropic Cosmological Models Without Singularity,

    A. A. Starobinsky, “A New Type of Isotropic Cosmological Models Without Singularity,” Phys. Lett. B , vol. 91, pp. 99–102, 1980

  6. [6]

    Particle physics models of inflation and the cosmological density perturbation,

    D. H. Lyth and A. Riotto, “Particle physics models of inflation and the cosmological density perturbation,” Phys. Rept., vol. 314, pp. 1–146, 1999

  7. [7]

    Gravitational waves from infla- tion,

    M. C. Guzzetti, N. Bartolo, M. Liguori, and S. Matarrese, “Gravitational waves from infla- tion,” Riv. Nuovo Cim. , vol. 39, no. 9, pp. 399–495, 2016

  8. [8]

    Cosmological Backgrounds of Gravitational Waves,

    C. Caprini and D. G. Figueroa, “Cosmological Backgrounds of Gravitational Waves,” Class. Quant. Grav., vol. 35, no. 16, p. 163001, 2018

  9. [9]

    Relating gravitational wave constraints from primordial nu- cleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early Universe,

    L. A. Boyle and A. Buonanno, “Relating gravitational wave constraints from primordial nu- cleosynthesis, pulsar timing, laser interferometers, and the CMB: Implications for the early Universe,” Phys. Rev. D , vol. 78, p. 043531, 2008

  10. [10]

    Gravitational Wave Production right after a Primordial Black Hole Evaporation,

    K. Inomata, M. Kawasaki, K. Mukaida, T. Terada, and T. T. Yanagida, “Gravitational Wave Production right after a Primordial Black Hole Evaporation,” Phys. Rev. D , vol. 101, no. 12, p. 123533, 2020

  11. [11]

    Anisotropies and non-Gaussianity of the Cosmological Gravitational Wave Background,

    N. Bartolo, D. Bertacca, S. Matarrese, M. Peloso, A. Ricciardone, A. Riotto, and G. Tasinato, “Anisotropies and non-Gaussianity of the Cosmological Gravitational Wave Background,” Phys. Rev. D , vol. 100, no. 12, p. 121501, 2019

  12. [12]

    Characterizing the cosmological gravitational wave background: Anisotropies and non- Gaussianity,

    N. Bartolo, D. Bertacca, S. Matarrese, M. Peloso, A. Ricciardone, A. Riotto, and G. Tasi- nato, “Characterizing the cosmological gravitational wave background: Anisotropies and non- Gaussianity,” Phys. Rev. D , vol. 102, no. 2, p. 023527, 2020

  13. [13]

    Probing anisotropies of the Stochastic Gravitational Wave Background with LISA,

    N. Bartolo et al. , “Probing anisotropies of the Stochastic Gravitational Wave Background with LISA,” JCAP, vol. 11, p. 009, 2022

  14. [14]

    Gravitational wave experiments and early universe cosmology,

    M. Maggiore, “Gravitational wave experiments and early universe cosmology,” Phys. Rept. , vol. 331, pp. 283–367, 2000

  15. [15]

    The Quest for B Modes from Inflationary Gravitational Waves,

    M. Kamionkowski and E. D. Kovetz, “The Quest for B Modes from Inflationary Gravitational Waves,” Ann. Rev. Astron. Astrophys. , vol. 54, pp. 227–269, 2016

  16. [16]

    Improved Calculation of the Primordial Gravitational Wave Spectrum in the Standard Model,

    Y. Watanabe and E. Komatsu, “Improved Calculation of the Primordial Gravitational Wave Spectrum in the Standard Model,” Phys. Rev. D , vol. 73, p. 123515, 2006. 17

  17. [17]

    Probing the early history of cosmic reionization by future cosmic microwave background experiments,

    H. Sakamoto, K. Ahn, K. Ichiki, H. Moon, and K. Hasegawa, “Probing the early history of cosmic reionization by future cosmic microwave background experiments,” The Astrophysical Journal, vol. 930, no. 2, p. 140, 2022

  18. [18]

    CMB-S4: Forecasting Constraints on Primordial Gravitational Waves,

    K. Abazajian et al., “CMB-S4: Forecasting Constraints on Primordial Gravitational Waves,” Astrophys. J., vol. 926, no. 1, p. 54, 2022

  19. [19]

    Measuring the spectrum of primor- dial gravitational waves with CMB, PTA and Laser Interferometers,

    P. Campeti, E. Komatsu, D. Poletti, and C. Baccigalupi, “Measuring the spectrum of primor- dial gravitational waves with CMB, PTA and Laser Interferometers,” JCAP, vol. 01, p. 012, 2021

  20. [20]

    Improved reconstruction of a stochastic gravitational wave background with LISA,

    R. Flauger, N. Karnesis, G. Nardini, M. Pieroni, A. Ricciardone, and J. Torrado, “Improved reconstruction of a stochastic gravitational wave background with LISA,” JCAP, vol. 01, p. 059, 2021

  21. [21]

    Probing Cosmic Inflation with the LiteBIRD Cosmic Microwave Background Polarization Survey,

    E. Allys et al., “Probing Cosmic Inflation with the LiteBIRD Cosmic Microwave Background Polarization Survey,” PTEP, vol. 2023, no. 4, p. 042F01, 2023

  22. [22]

    Impact of correlated noise on the reconstruction of the stochastic gravitational wave background with Einstein Telescope,

    I. Caporali, G. Capurri, W. Del Pozzo, A. Ricciardone, and L. Valbusa Dall’Armi, “Impact of correlated noise on the reconstruction of the stochastic gravitational wave background with Einstein Telescope,” 1 2025

  23. [23]

    Science with the Einstein Telescope: a comparison of different designs,

    M. Branchesi et al., “Science with the Einstein Telescope: a comparison of different designs,” JCAP, vol. 07, p. 068, 2023

  24. [24]

    Gravitational waves from inflation in LISA: reconstruction pipeline and physics interpretation,

    M. Braglia et al. , “Gravitational waves from inflation in LISA: reconstruction pipeline and physics interpretation,” JCAP, vol. 11, p. 032, 2024

  25. [25]

    The Science of the Einstein Telescope,

    A. Abac et al. , “The Science of the Einstein Telescope,” 3 2025

  26. [26]

    The NANOGrav 15 yr Data Set: Search for Signals from New Physics,

    A. Afzal et al. , “The NANOGrav 15 yr Data Set: Search for Signals from New Physics,” Astrophys. J. Lett. , vol. 951, no. 1, p. L11, 2023

  27. [27]

    European Pulsar Timing Array Limits On An Isotropic Stochastic Gravitational-Wave Background,

    L. Lentati et al. , “European Pulsar Timing Array Limits On An Isotropic Stochastic Gravitational-Wave Background,” Mon. Not. Roy. Astron. Soc. , vol. 453, no. 3, pp. 2576– 2598, 2015

  28. [28]

    The second data release from the European Pulsar Timing Array - IV. Implications for massive black holes, dark matter, and the early Universe,

    J. Antoniadis et al. , “The second data release from the European Pulsar Timing Array - IV. Implications for massive black holes, dark matter, and the early Universe,”Astron. Astrophys., vol. 685, p. A94, 2024

  29. [29]

    Searching for the Nano-Hertz Stochastic Gravitational Wave Background with the Chinese Pulsar Timing Array Data Release I,

    H. Xu et al. , “Searching for the Nano-Hertz Stochastic Gravitational Wave Background with the Chinese Pulsar Timing Array Data Release I,” Res. Astron. Astrophys. , vol. 23, no. 7, p. 075024, 2023

  30. [30]

    The Gravitational-wave Background Null Hypothesis: Characterizing Noise in Millisecond Pulsar Arrival Times with the Parkes Pulsar Timing Array,

    D. J. Reardon et al. , “The Gravitational-wave Background Null Hypothesis: Characterizing Noise in Millisecond Pulsar Arrival Times with the Parkes Pulsar Timing Array,” Astrophys. J. Lett., vol. 951, no. 1, p. L7, 2023

  31. [31]

    Upper Limits on the Isotropic Gravitational Radiation Background from Pulsar Timing Analysis,

    R. w. Hellings and G. s. Downs, “Upper Limits on the Isotropic Gravitational Radiation Background from Pulsar Timing Analysis,” Astrophys. J. Lett. , vol. 265, pp. L39–L42, 1983. 18

  32. [32]

    Gravitational waves from resolvable massive black hole binary systems and observations with Pulsar Timing Arrays,

    A. Sesana, A. Vecchio, and M. Volonteri, “Gravitational waves from resolvable massive black hole binary systems and observations with Pulsar Timing Arrays,” Mon. Not. Roy. Astron. Soc., vol. 394, p. 2255, 2009

  33. [33]

    The Astrophysics of Nanohertz Gravitational Waves,

    S. Burke-Spolaor et al. , “The Astrophysics of Nanohertz Gravitational Waves,” Astron. As- trophys. Rev., vol. 27, no. 1, p. 5, 2019

  34. [34]

    The NANOGrav 12.5 yr Data Set: Search for an Isotropic Stochastic Gravitational-wave Background,

    Z. Arzoumanian et al., “The NANOGrav 12.5 yr Data Set: Search for an Isotropic Stochastic Gravitational-wave Background,” Astrophys. J. Lett. , vol. 905, no. 2, p. L34, 2020

  35. [35]

    Second order perturbations of the Einstein-de Sitter universe,

    S. Matarrese, S. Mollerach, and M. Bruni, “Second order perturbations of the Einstein-de Sitter universe,” Phys. Rev. D , vol. 58, p. 043504, 1998

  36. [36]

    Semianalytic calculation of gravitational wave spectrum nonlinearly induced from primordial curvature perturbations,

    K. Kohri and T. Terada, “Semianalytic calculation of gravitational wave spectrum nonlinearly induced from primordial curvature perturbations,” Phys. Rev. D , vol. 97, no. 12, p. 123532, 2018

  37. [37]

    Scalar Induced Gravitational Waves Review,

    G. Dom` enech, “Scalar Induced Gravitational Waves Review,”Universe, vol. 7, no. 11, p. 398, 2021

  38. [38]

    Gravitational Waves Induced by Scalar Perturbations during a Gradual Transition from an Early Matter Era to the Radiation Era,

    K. Inomata, K. Kohri, T. Nakama, and T. Terada, “Gravitational Waves Induced by Scalar Perturbations during a Gradual Transition from an Early Matter Era to the Radiation Era,” JCAP, vol. 10, p. 071, 2019. [Erratum: JCAP 08, E01 (2023)]

  39. [39]

    Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations,

    D. Baumann, P. J. Steinhardt, K. Takahashi, and K. Ichiki, “Gravitational Wave Spectrum Induced by Primordial Scalar Perturbations,” Phys. Rev. D , vol. 76, p. 084019, 2007

  40. [40]

    A Cosmological Signature of the SM Higgs Insta- bility: Gravitational Waves,

    J. R. Espinosa, D. Racco, and A. Riotto, “A Cosmological Signature of the SM Higgs Insta- bility: Gravitational Waves,” JCAP, vol. 09, p. 012, 2018

  41. [41]

    Fully non-Gaussian Scalar-Induced Gravitational Waves,

    G. Perna, C. Testini, A. Ricciardone, and S. Matarrese, “Fully non-Gaussian Scalar-Induced Gravitational Waves,” JCAP, vol. 05, p. 086, 2024

  42. [42]

    Scalar-Induced Gravitational Waves in Modified Gravity,

    A. A. Kugarajh, M. Traforetti, A. Maselli, S. Matarrese, and A. Ricciardone, “Scalar-Induced Gravitational Waves in Modified Gravity,” 2 2025

  43. [43]

    Reconstructing Primordial Curvature Perturbations via Scalar-Induced Gravitational Waves with LISA,

    J. E. Gammal et al., “Reconstructing Primordial Curvature Perturbations via Scalar-Induced Gravitational Waves with LISA,” 1 2025

  44. [44]

    Observation of Gravitational Waves from a Binary Black Hole Merger,

    B. P. Abbott et al., “Observation of Gravitational Waves from a Binary Black Hole Merger,” Phys. Rev. Lett. , vol. 116, no. 6, p. 061102, 2016

  45. [45]

    Seeking Inflation Fossils in the Cosmic Microwave Background,

    L. Dai, D. Jeong, and M. Kamionkowski, “Seeking Inflation Fossils in the Cosmic Microwave Background,” Phys. Rev. D , vol. 87, no. 10, p. 103006, 2013

  46. [46]

    Clustering Fossils from the Early Universe,

    D. Jeong and M. Kamionkowski, “Clustering Fossils from the Early Universe,” Phys. Rev. Lett., vol. 108, p. 251301, 2012

  47. [47]

    Primordial gravity wave fossils and their use in testing inflation,

    K. W. Masui and U.-L. Pen, “Primordial gravity wave fossils and their use in testing inflation,” Phys. Rev. Lett. , vol. 105, p. 161302, 2010

  48. [48]

    Inflationary tensor fossils in large-scale structure,

    E. Dimastrogiovanni, M. Fasiello, D. Jeong, and M. Kamionkowski, “Inflationary tensor fossils in large-scale structure,” JCAP, vol. 12, p. 050, 2014. 19

  49. [49]

    Anisotropic tensor power spectrum at interferometer scales induced by tensor squeezed non-Gaussianity,

    A. Ricciardone and G. Tasinato, “Anisotropic tensor power spectrum at interferometer scales induced by tensor squeezed non-Gaussianity,” JCAP, vol. 02, p. 011, 2018

  50. [50]

    Primordial gravitational waves in supersolid inflation,

    A. Ricciardone and G. Tasinato, “Primordial gravitational waves in supersolid inflation,” Phys. Rev. D , vol. 96, no. 2, p. 023508, 2017

  51. [51]

    Bending of light by gravity waves,

    N. Kaiser and A. H. Jaffe, “Bending of light by gravity waves,” Astrophys. J. , vol. 484, pp. 545–554, 1997

  52. [52]

    Large-Scale Structure with Gravitational Waves I: Galaxy Clus- tering,

    D. Jeong and F. Schmidt, “Large-Scale Structure with Gravitational Waves I: Galaxy Clus- tering,” Phys. Rev. D , vol. 86, p. 083512, 2012

  53. [53]

    Large-Scale Structure with Gravitational Waves II: Shear,

    F. Schmidt and D. Jeong, “Large-Scale Structure with Gravitational Waves II: Shear,” Phys. Rev. D, vol. 86, p. 083513, 2012

  54. [54]

    Non-Linear Theory of Gravitational Instability in the Expanding Universe,

    K. Tomita, “Non-Linear Theory of Gravitational Instability in the Expanding Universe,”Prog. Theor. Phys., vol. 37, no. 5, pp. 831–846, 1967

  55. [55]

    Signatures of Primordial Gravitational Waves on the Large-Scale Structure of the Universe,

    P. Bari, A. Ricciardone, N. Bartolo, D. Bertacca, and S. Matarrese, “Signatures of Primordial Gravitational Waves on the Large-Scale Structure of the Universe,” Phys. Rev. Lett., vol. 129, no. 9, p. 091301, 2022

  56. [56]

    An an- alytical study of the primordial gravitational-wave-induced contribution to the large-scale structure of the Universe,

    P. Bari, D. Bertacca, N. Bartolo, A. Ricciardone, S. Giardiello, and S. Matarrese, “An an- alytical study of the primordial gravitational-wave-induced contribution to the large-scale structure of the Universe,” JCAP, vol. 07, p. 034, 2023

  57. [57]

    Euclid preparation. VII. Forecast validation for Euclid cosmological probes,

    A. Blanchard et al. , “Euclid preparation. VII. Forecast validation for Euclid cosmological probes,” Astron. Astrophys., vol. 642, p. A191, 2020

  58. [58]

    Overview of the DESI Legacy Imaging Surveys,

    A. Dey et al. , “Overview of the DESI Legacy Imaging Surveys,” Astron. J., vol. 157, no. 5, p. 168, 2019

  59. [59]

    Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary Science,

    O. Dor´ eet al. , “Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary Science,” 6 2016

  60. [60]

    Cosmology with Phase 1 of the Square Kilometre Array: Red Book 2018: Technical specifications and performance forecasts,

    D. J. Bacon et al. , “Cosmology with Phase 1 of the Square Kilometre Array: Red Book 2018: Technical specifications and performance forecasts,” Publ. Astron. Soc. Austral., vol. 37, p. e007, 2020

  61. [61]

    A Reference Survey for Supernova Cosmology with the Nancy Grace Roman Space Telescope,

    B. M. Rose et al. , “A Reference Survey for Supernova Cosmology with the Nancy Grace Roman Space Telescope,” 11 2021

  62. [62]

    The Impact of Observing Strategy on Cosmological Constraints with LSST,

    M. Lochner et al. , “The Impact of Observing Strategy on Cosmological Constraints with LSST,” Astrophys. J. Supp. , vol. 259, no. 2, p. 58, 2022

  63. [63]

    Inflation without an Inflaton,

    D. Bertacca, R. Jimenez, S. Matarrese, and A. Ricciardone, “Inflation without an Inflaton,” 12 2024

  64. [64]

    Non-Gaussianity from inflation: The- ory and observations,

    N. Bartolo, E. Komatsu, S. Matarrese, and A. Riotto, “Non-Gaussianity from inflation: The- ory and observations,” Phys. Rept., vol. 402, pp. 103–266, 2004

  65. [65]

    Primordial non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Struc- ture,

    M. Liguori, E. Sefusatti, J. R. Fergusson, and E. P. S. Shellard, “Primordial non-Gaussianity and Bispectrum Measurements in the Cosmic Microwave Background and Large-Scale Struc- ture,” Adv. Astron., vol. 2010, p. 980523, 2010. 20

  66. [66]

    Primordial Non-Gaussianity,

    M. Celoria and S. Matarrese, “Primordial Non-Gaussianity,” Proc. Int. Sch. Phys. Fermi , vol. 200, pp. 179–215, 2020

  67. [67]

    Tests for primordial nonGaus- sianity,

    L. Verde, R. Jimenez, M. Kamionkowski, and S. Matarrese, “Tests for primordial nonGaus- sianity,” Mon. Not. Roy. Astron. Soc. , vol. 325, p. 412, 2001

  68. [68]

    Scale-dependent gravitational waves from a rolling axion,

    R. Namba, M. Peloso, M. Shiraishi, L. Sorbo, and C. Unal, “Scale-dependent gravitational waves from a rolling axion,” JCAP, vol. 01, p. 041, 2016

  69. [69]

    Primordial Gravitational Waves from Axion- Gauge Fields Dynamics,

    E. Dimastrogiovanni, M. Fasiello, and T. Fujita, “Primordial Gravitational Waves from Axion- Gauge Fields Dynamics,” JCAP, vol. 01, p. 019, 2017

  70. [70]

    Finding the chiral gravitational wave background of an axion-SU(2) inflationary model using CMB observations and laser interferometers,

    B. Thorne, T. Fujita, M. Hazumi, N. Katayama, E. Komatsu, and M. Shiraishi, “Finding the chiral gravitational wave background of an axion-SU(2) inflationary model using CMB observations and laser interferometers,” Phys. Rev. D , vol. 97, no. 4, p. 043506, 2018

  71. [71]

    Cosmological Perturbation Theory,

    H. Kodama and M. Sasaki, “Cosmological Perturbation Theory,” Prog. Theor. Phys. Suppl. , vol. 78, pp. 1–166, 1984

  72. [72]

    PostNewtonian cosmological dynamics in Lagrangian coor- dinates,

    S. Matarrese and D. Terranova, “PostNewtonian cosmological dynamics in Lagrangian coor- dinates,” Mon. Not. Roy. Astron. Soc. , vol. 283, pp. 400–418, 1996

  73. [73]

    Contributions to the relativistic mechanics of continuous media,

    J. Ehlers, “Contributions to the relativistic mechanics of continuous media,” Abh. Akad. Wiss. Lit. Mainz. Nat. Kl. , vol. 11, pp. 793–837, 1961

  74. [74]

    Relativistic cosmology. 1.,

    A. Raychaudhuri, “Relativistic cosmology. 1.,” Phys. Rev., vol. 98, pp. 1123–1126, 1955

  75. [75]

    The Maximal Amount of Gravita- tional Waves in the Curvaton Scenario,

    N. Bartolo, S. Matarrese, A. Riotto, and A. Vaihkonen, “The Maximal Amount of Gravita- tional Waves in the Curvaton Scenario,” Phys. Rev. D , vol. 76, p. 061302, 2007

  76. [76]

    J. A. Peacock, Cosmological physics. Cambridge University Press, 2010

  77. [77]

    The Cosmological constant,

    S. M. Carroll, “The Cosmological constant,” Living Rev. Rel. , vol. 4, p. 1, 2001

  78. [78]

    Planck 2018 results. VI. Cosmological parameters,

    N. Aghanim et al. , “Planck 2018 results. VI. Cosmological parameters,” Astron. Astrophys., vol. 641, p. A6, 2020. [Erratum: Astron.Astrophys. 652, C4 (2021)]

  79. [79]

    Large Nongaussianity in Axion Inflation,

    N. Barnaby and M. Peloso, “Large Nongaussianity in Axion Inflation,” Phys. Rev. Lett. , vol. 106, p. 181301, 2011

  80. [80]

    Parity violation in the Cosmic Microwave Background from a pseudoscalar infla- ton,

    L. Sorbo, “Parity violation in the Cosmic Microwave Background from a pseudoscalar infla- ton,” JCAP, vol. 06, p. 003, 2011

Showing first 80 references.