CMB 
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 cross correlations as a probe of primordial black hole scenarios

Özsoy, Ogan; Tasinato, Gianmassimo

doi:10.1103/physrevd.104.043526

Cited by 18 publications

(3 citation statements)

References 75 publications

(96 reference statements)

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“…These relations are valid for any single-field models that enhance the spectrum through a brief deviation from the standard attractor era, including cases with a time-varying sound speed and Planck mass. They are accompanied by consistency conditions on the squeezed limit of non-Gaussian higher-order point functions around the dip [227][228][229], as expected in single-field scenarios 22 .…”

Section: The Features Of the Spectrum: Analytic Considerationsmentioning

confidence: 52%

Inflation and Primordial Black Holes

Özsoy

Tasinato

2023

Universe

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We review conceptual aspects of inflationary scenarios able to produce primordial black holes by amplifying the size of curvature fluctuations to the level required to trigger black hole formation. We identify general mechanisms to do so, both for single- and multiple-field inflation. In single-field inflation, the spectrum of curvature fluctuations is enhanced by pronounced gradients of background quantities controlling the cosmological dynamics, which can induce brief phases of non-slow-roll inflationary evolution. In multiple-field inflation, the amplification occurs through appropriate couplings with additional sectors characterized by tachyonic instabilities that enhance the size of their fluctuations. As representative examples, we consider axion inflation and two-field models of inflation with rapid turns in field space. We develop our discussion in a pedagogical manner by including some of the most relevant calculations and by guiding the reader through the existing theoretical literature, emphasizing general themes common to several models.

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Section: The Features Of the Spectrum: Analytic Considerationsmentioning

confidence: 52%

Inflation and Primordial Black Holes

Özsoy

Tasinato

2023

Universe

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“…As a result, it can be expected that any higher order correlation function involving the wave number also identically vanishes (for a detailed discussion regarding the dip, see Refs. [58,119,[147][148][149]). We should add that the bispectra also contain additional features that are unique to the nature of the terms in the cubic order action and the corresponding integrals involved in the computation. )…”

Section: Numerical Computation Of the Scalar Bispectrum And The Assoc...mentioning

confidence: 99%

Observational Imprints of Enhanced Scalar Power on Small Scales in Ultra Slow Roll Inflation and Associated Non-Gaussianities

Ragavendra

Sriramkumar

2023

Galaxies

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The discovery of gravitational waves from merging binary black holes has generated considerable interest in examining whether these black holes could have a primordial origin. If a significant number of black holes have to be produced in the early universe, the primordial scalar power spectrum should have an enhanced amplitude on small scales, when compared to the COBE normalized values on the large scales that is strongly constrained by the anisotropies in the cosmic microwave background. In the inflationary scenario driven by a single, canonical scalar field, such power spectra can be achieved in models that permit a brief period of ultra slow roll inflation during which the first slow roll parameter decreases exponentially. In this review, we shall consider a handful of such inflationary models as well as a reconstructed scenario and examine the extent of formation of primordial black holes and the generation of secondary gravitational waves in these cases. We shall also discuss the strength and shape of the scalar bispectrum and the associated non-Gaussianity parameter that arise in such situations. We shall conclude with an outlook wherein we discuss the wider implications of the increased strengths of the non-Gaussianities on smaller scales.

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“…This avenue was opened by Pajer & Zaldarriaga ( 2012 ) and Ganc & Komatsu ( 2012 ) and further extended and quantitatively refined in Emami et al ( 2015 ), Ota ( 2016 ), Chluba et al ( 2017 ), Ravenni et al ( 2017 ), and Cabass, Pajer & van der Woude ( 2018 ). Recently it has been shown how the same idea can be applied to models involving primordial black holes ( Özsoy & Tasinato 2021 ; Ze ge ye, Inomata & Hu 2021 ) and to models in which scalar and tensor perturbations are correlated (Orlando, Meerburg & Patil 2022 ). While fainter than the monopole signal, SDAs do not require (Ganc & Komatsu 2012 ) the use of a purposefully built absolutely calibrated spectrometer (Chluba et al 2019 ), ho we ver can be extracted from differential measurement carried out by an imager (e.g.…”

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confidence: 96%

Leverage on small-scale primordial non-Gaussianity through cross-correlations between CMB E-mode and μ-distortion anisotropies

Remazeilles

Ravenni

Chluba

2022

Monthly Notices of the Royal Astronomical Society

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Multi-field inflation models and non-Bunch-Davies vacuum initial conditions both predict sizeable non-Gaussian primordial perturbations and anisotropic μ-type spectral distortions of the cosmic microwave background (CMB) blackbody. While CMB anisotropies allow us to probe non-Gaussianity at wavenumbers k ≃ 0.05 Mpc−1, μ-distortion anisotropies are related to non-Gaussianity of primordial perturbation modes with much larger wavenumbers, k ≃ 740 Mpc−1. Through cross-correlations between CMB and μ-distortion anisotropies, one can therefore shed light on the aforementioned inflation models. We investigate the ability of a future CMB satellite imager like LiteBIRD to measure μT and μE cross-power spectra between anisotropic μ-distortions and CMB temperature and E-mode polarization anisotropies in the presence of foregrounds, and derive LiteBIRD forecasts on ${f_{\rm NL}^\mu (k\simeq 740\, {\rm Mpc^{-1}})}$. We show that μE cross-correlations with CMB polarization provide more constraining power on $f_{\rm NL}^\mu$ than μT cross-correlations in the presence of foregrounds, and the joint combination of μT and μE observables adds further leverage to the detection of small-scale primordial non-Gaussianity. For multi-field inflation, we find that LiteBIRD would detect ${f_{\rm NL}^\mu }=4500$ at 5σ significance after foreground removal, and achieve a minimum error of ${\sigma (f_{\rm NL}^\mu =0) \simeq 800}$ at 68% CL by combining CMB temperature and polarization. Due to the huge dynamic range of wavenumbers between CMB and μ-distortion anisotropies, such large $f^\mu _{\rm NL}$ values would still be consistent with current CMB constraints in the case of very mild scale-dependence of primordial non-Gaussianity. Anisotropic spectral distortions thus provide a new path, complementary to CMB B-modes, to probe inflation with LiteBIRD.

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CMB μT cross correlations as a probe of primordial black hole scenarios

Cited by 18 publications

References 75 publications

Inflation and Primordial Black Holes

Inflation and Primordial Black Holes

Observational Imprints of Enhanced Scalar Power on Small Scales in Ultra Slow Roll Inflation and Associated Non-Gaussianities

Leverage on small-scale primordial non-Gaussianity through cross-correlations between CMB E-mode and μ-distortion anisotropies

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