Curvature bounce in general relativity: background and primordial spectrum

Renevey, Cyril; Barrau, A.; Martineau, Killian; Touati, Selim

doi:10.1088/1475-7516/2021/01/018

Cited by 12 publications

(9 citation statements)

References 44 publications

(66 reference statements)

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“…We however want to emphasize that contrarily to what if often believed, a past singularity is not unavoidable in GR, even without exotic matter contents[19,20].…”

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confidence: 90%

Cosmological implications of generalized holonomy corrections

Renevey,

Martineau,

Barrau

2021

Preprint

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Most of the phenomenology of loop quantum gravity in the cosmological sector is based on the so-called holonomy correction to the Hamiltonian constraint. It straightforwardly modifies the Friedmann equations. In this work, we investigate the influence of corrections generalizing the one usually used in loop quantum cosmology. We find that a long enough inflation phase can be generated by purely quantum geometrical effects but we also underline the limitations of this scenario. In addition, we study the effects of generalized holonomy corrections on an inflationary phase generated by a massive scalar field. At the level of perturbations, we investigate in details the consequences on the primordial scalar power spectrum.

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“…We however want to emphasize that contrarily to what if often believed, a past singularity is not unavoidable in GR, even without exotic matter contents[19,20].…”

mentioning

confidence: 90%

Cosmological implications of generalized holonomy corrections

Renevey,

Martineau,

Barrau

2021

Preprint

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“…Quite a lot of theories beyond general relativity predict a cosmological bounce instead of the Big Bang singularity (see, e.g., [24][25][26] for reviews). This is even possible in general relativity without exotic matter [27,28]. In such models, the Universe was contracting before entering the current expanding branch.…”

Section: The Contracting Universe Catastrophementioning

confidence: 99%

The catastrophic fate of Schwarzschild black holes in a thermal bath

Barrau¹,

Martineau²,

Renevey³

2022

Preprint

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Using the Schwazchild metric as a rudimentary toy-model, we pedagogically revisit the curious prediction that the mass of a classical black hole in a constant temperature thermal bath diverges in a finite amount of time. We study in details how this instability behaves if the temperature of the bath is allowed to vary with time and conclude that whatever the background behavior (but for a zero-measure subspace of the initial conditions), the black hole mass either diverges or vanishes in a finite time if the Hawking radiation is taken into account. The competition between both effects is subtle and not entirely governed by the hierarchy of the relevant temperatures. This instability is also shown to be reached before the background singularity in a contracting universe, which has implications for bouncing models. The results are generalized to spaces with extra-dimensions and the main conclusions are shown to remain true. The limitations of the model are reviewed, both from the point of view of the dynamical black hole horizon and from the point of view of the background space expansion. Comparisons with other approaches are suggested and possible developments are underlined.

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“…The singular origin of our universe is naturally regularized thanks to the positive curvature combined with inflation. A further numerical investigation was carried out in [14]. Quite impressively, the usual claims about the need of a quantum (or modified) theory of gravity to escape the unavoidable singularity are simply contradicted using only the hypotheses of the standard cosmological scenario (if space is positively curved).…”

Section: Introductionmentioning

confidence: 99%

Detailed analysis of the curvature bounce: background dynamics and imprints in the CMB

Renevey,

Barrau,

Martineau

2022

Preprint

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If the spatial sections of the Universe are positively curved, extrapolating the inflationary stage backward in time inevitably leads to a classical bounce. This simple scenario, non-singular and free of exotic physics, deserves to be investigated in details. The background dynamics exhibits interesting features and is shown to be mostly insensitive to initial conditions as long as observational consequences are considered. The primordial scalar power spectrum is explicitly computed, for different inflaton potentials, and the subsequent CMB temperature anisotropies are calculated. The results are compatible with current measurements. Some deviations with respect to the standard paradigm can however appear at large scales and we carefully disentangle what is associated with the vacuum choice with what is more fundamentally due to the bounce itself.

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Curvature bounce in general relativity: background and primordial spectrum

Cited by 12 publications

References 44 publications

Cosmological implications of generalized holonomy corrections

Cosmological implications of generalized holonomy corrections

The catastrophic fate of Schwarzschild black holes in a thermal bath

Detailed analysis of the curvature bounce: background dynamics and imprints in the CMB

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