scholarly journals Spectrum of tensor perturbations in warm inflation

2021 ◽  
Vol 104 (8) ◽  
Author(s):  
Yue Qiu ◽  
Lorenzo Sorbo
Keyword(s):  
Warm Inflation ◽  
Tensor Perturbations

Gravitational Waves

2018 ◽  
Author(s):  
Michele Maggiore
Keyword(s):  
Black Hole ◽  
Perturbation Theory ◽  
Gravitational Waves ◽  
Transfer Functions ◽  
Normal Modes ◽  
Cosmological Perturbation ◽  
Tests Of General Relativity ◽  
Pulsar Timing ◽  
Tensor Perturbations ◽  
Stochastic Backgrounds

A comprehensive and detailed account of the physics of gravitational waves and their role in astrophysics and cosmology. The part on astrophysical sources of gravitational waves includes chapters on GWs from supernovae, neutron stars (neutron star normal modes, CFS instability, r-modes), black-hole perturbation theory (Regge-Wheeler and Zerilli equations, Teukoslky equation for rotating BHs, quasi-normal modes) coalescing compact binaries (effective one-body formalism, numerical relativity), discovery of gravitational waves at the advanced LIGO interferometers (discoveries of GW150914, GW151226, tests of general relativity, astrophysical implications), supermassive black holes (supermassive black-hole binaries, EMRI, relevance for LISA and pulsar timing arrays). The part on gravitational waves and cosmology include discussions of FRW cosmology, cosmological perturbation theory (helicity decomposition, scalar and tensor perturbations, Bardeen variables, power spectra, transfer functions for scalar and tensor modes), the effects of GWs on the Cosmic Microwave Background (ISW effect, CMB polarization, E and B modes), inflation (amplification of vacuum fluctuations, quantum fields in curved space, generation of scalar and tensor perturbations, Mukhanov-Sasaki equation,reheating, preheating), stochastic backgrounds of cosmological origin (phase transitions, cosmic strings, alternatives to inflation, bounds on primordial GWs) and search of stochastic backgrounds with Pulsar Timing Arrays (PTA).

scholarly journals Robustness of inflation to large tensor perturbations

2018 ◽  
Vol 2018 (05) ◽  
pp. 065-065 ◽  
Author(s):  
Katy Clough ◽  
Raphael Flauger ◽  
Eugene A. Lim
Keyword(s):  
Tensor Perturbations

scholarly journals Dynamics of polynomial Chaplygin gas warm inflation

2017 ◽  
Vol 77 (11) ◽  
Author(s):  
Abdul Jawad ◽  
Shahid Chaudhary ◽  
Nelson Videla
Keyword(s):  
Chaplygin Gas ◽  
Warm Inflation

scholarly journals Scalar and tensor perturbations in DHOST bounce cosmology

2021 ◽  
Vol 2021 (11) ◽  
pp. 045
Author(s):  
Mian Zhu ◽  
Amara Ilyas ◽  
Yunlong Zheng ◽  
Yi-Fu Cai ◽  
Emmanuel N. Saridakis
Keyword(s):  
Scale Invariance ◽  
Initial Conditions ◽  
Power Spectra ◽  
Thermal Fluctuations ◽  
Spectral Indices ◽  
Vacuum Fluctuations ◽  
Perfect Agreement ◽  
Expansion Phase ◽  
Contraction Phase ◽  
Tensor Perturbations

Abstract We investigate the bounce realization in the framework of DHOST cosmology, focusing on the relation with observables. We perform a detailed analysis of the scalar and tensor perturbations during the Ekpyrotic contraction phase, the bounce phase, and the fast-roll expansion phase, calculating the power spectra, the spectral indices and the tensor-to-scalar ratio. Furthermore, we study the initial conditions, incorporating perturbations generated by Ekpyrotic vacuum fluctuations, by matter vacuum fluctuations, and by thermal fluctuations. The scale invariance of the scalar power spectrum can be acquired introducing a matter contraction phase before the Ekpyrotic phase, or invoking a thermal gas as the source. The DHOST bounce scenario with cosmological perturbations generated by thermal fluctuations proves to be the most efficient one, and the corresponding predictions are in perfect agreement with observational bounds. Especially the tensor-to-scalar ratio is many orders of magnitude within the allowed region, since it is suppressed by the Hubble parameter at the beginning of the bounce phase.

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