Article
Astronomy & Astrophysics
Alberto Salvio
Summary: The study calculates the relic gravitational wave background generated by tensor linear perturbations during Higgs inflation, considering both the Standard Model and a well-motivated phenomenological completion. It focuses on critical Higgs inflation, which amplifies the tensor fluctuations and suggests that future space-borne interferometers may detect the corresponding primordial gravitational waves.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Mar Bastero-Gil, Antonio Torres Manso
Summary: Investigated the phenomenology of scalar-field interactions with photons and examined the generation of coupled vector particles and calculation of gravitational wave spectra.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Andreas Ringwald, Ken'ichi Saikawa, Carlos Tamarit
Summary: This paper analyzes the spectrum of primordial gravitational waves predicted in the SMASH model, which addresses multiple fundamental problems in particle physics and cosmology. The unique prediction for the critical temperature of the PQ phase transition in the model leads to a drastic change in the universe's equation of state. Future high sensitivity GW experiments, like DECIGO, are expected to detect the nontrivial features resulting from the PQ phase transition in this model.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
P. Klose, M. Laine, S. Procacci
Summary: A study on the interaction between a pseudoscalar inflaton and a non-Abelian sector reveals that this coupling can efficiently heat up the medium through the production of gauge bosons. By analyzing hydrodynamic fluctuations and particle collisions, a lower bound for the production rate of gravitational waves is determined, indicating that non-Abelian models may avoid overproduction.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
P. Klose, M. Laine, S. Procacci
Summary: In this paper, the framework of axion-like inflation is revisited considering the possibility of the inflaton coupling to a non-Abelian topological charge density, which could result in the generation of a rapidly thermalizing heat bath. Both dispersive and absorptive effects are taken into account. It is found that, for phenomenologically viable parameters, the system remains in a weak regime of warm inflation. An interpolating formula for tensor perturbations is derived, which incorporates both vacuum and thermal production. The coefficient in the thermal production yields a model-independent frequency shape similar to f03 in the LISA window, and it can be used to measure the maximal shear viscosity of the thermal epoch. However, finding models with a large enough coefficient to be observable is a challenge.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Muhammad Atif Masoud, Mansoor Ur Rehman, Qaisar Shafi
Summary: This study presents a successful realization of the sneutrino tribrid inflation model based on a gauged U(1)(B-L) extension of the Minimal Supersymmetric Standard Model (MSSM). By involving a single interaction term, it achieves multiple purposes such as generating heavy Majorana masses for the right-handed neutrinos, explaining tiny neutrino masses via the seesaw mechanism, and successfully realizing inflation with right-handed sneutrino as the inflaton. Depending on the model parameters, predicted ranges for the tensor to scalar ratio, running of the scalar spectral index, and B-L breaking scale are provided. A discussion on the possibility of realizing metastable cosmic strings in a grand unified theory setup is also included.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
Yanou Cui, Evangelos I. Sfakianakis
Summary: This article investigates the production of gravitational waves during preheating in hybrid inflation models, where an axion-like waterfall field couples to Abelian gauge fields. The study finds that the gravitational wave signal from these models can be detected by foreseeable gravitational wave experiments such as LISA, AEDGE, ET, and CE, and is comparable to that of LIGO A+ in terms of frequency range and signal strength. Additionally, the resulting gravitational wave signal is helically polarized, which distinguishes it from other sources of stochastic gravitational wave background. Furthermore, these models can generate primordial black holes that can constitute dark matter and contribute to merger events detectable by gravitational wave detectors.
Article
Astronomy & Astrophysics
Thomas Kite, Jens Chluba, Andrea Ravenni, Subodh P. Patil
Summary: The researchers used numerical methods to explore the energy spectrum characteristics of the primordial gravitational wave background, discussing the effects of different eras in the early universe and their importance in cosmological parameters. Numerical analysis can reveal potential errors in previous literature and describe the effects of gravitational wave backgrounds at different scales.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Rinku Maji, Qaisar Shafi
Summary: We discuss the survival of topologically stable intermediate mass monopoles in SO(10) grand unification during inflation, driven by a Coleman-Weinberg potential and non-minimal coupling to gravity. The model predicts an agreement with current observations of the scalar spectral index ns, and a tensor to scalar ratio r >= 0.003. It also suggests the presence of intermediate scale topologically stable cosmic strings, whose gravitational wave spectrum reflects the amount of cosmic inflation experienced during symmetry breaking.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Philipp Gubler, Naoki Yamamoto, Di-Lun Yang
Summary: We investigate the polarized gravitational waves generated by chiral fermions in the early Universe, with a focus on the contribution from left-handed neutrinos in thermal equilibrium. The correlation functions of gravitational fields related to the circular polarization of gravitational waves are computed. It is found that thermalized neutrinos induce a non-vanishing circular polarization in the long wavelength region, linearly dependent on the neutrino degeneracy parameter and wavenumber of gravitational waves. Although the magnitude of these gravitational waves is currently undetectable, future detectors in ultra-high frequency regimes may provide information on the neutrino degeneracy parameter.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
C. P. Burgess, R. Holman, Greg Kaplanek, Jerome Martin, Vincent Vennin
Summary: This study computes the rate at which super-Hubble cosmological fluctuations decohere during inflation, due to their gravitational interactions with unobserved shorter-wavelength scalar and tensor modes. The study utilizes Open Effective Field Theory methods to obtain a minimal result, considering only the self-interactions predicted by General Relativity in single-clock models. The findings reveal that decoherence is suppressed by the first slow-roll parameter and the energy density during inflation, but enhanced by the volume within the scale of interest.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
John Ellis, Malcolm Fairbairn, Gert Hutsi, Martti Raidal, Juan Urrutia, Ville Vaskonen, Hardi Veermae
Summary: NANOGrav and other Pulsar Timing Arrays (PTAs) have discovered a common-spectrum process in the nHz range that may be due to gravitational waves (GWs) generated by black hole (BH) binaries with total masses greater than 10^9 solar masses. The Extended Press-Schechter formalism and a simple halo-BH mass relation suggest that these binaries have redshifts around 1 and mass ratios greater than 10, and that the GW signal above 10 nHz may be dominated by a few distinct binaries that can be observed with circular polarization. Extrapolating the model to higher frequencies shows that future GW detectors like LISA and AEDGE could expand PTA observations to BH masses greater than 10^3 solar masses.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Tomasz Krajewski, Krzysztof Turzynski
Summary: We study the post-inflationary evolution in alpha-attractor T-models of inflation, finding that the perturbations of the spectator field are more unstable than the perturbations of the inflaton field, thus dominating the dynamics of the early stages of preheating.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Tomasz Krajewski, Krzysztof Turzynski
Summary: This study focuses on the post-inflationary evolution in alpha-attractor T-models of inflation. By examining the dynamics of the scalar fields present in these models, namely the inflaton and the spectator, it is found that the perturbations of the spectator field are more unstable, thus dominating the dynamics of the early stages of preheating. Additionally, the spectrum of gravitational waves originating from scalar fluctuations is calculated to determine if the alpha-attractor T-models can be constrained or ruled out by current cosmological observations.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Basabendu Barman, Debasish Borah, Suruj Jyoti Dasb, Indrajit Sahab
Summary: This study investigates the relationship between primordial gravitational waves and beyond the Standard Model frameworks. By analyzing the NANOGrav 15 yr data, it is found that the scale of Dirac leptogenesis should be above 107 GeV, while the scale of minimal LRSM is about 106 GeV. The non-minimal LRSM can be compatible with the NANOGrav data, but violates collider bounds.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
