[HTML][HTML] Inflationary interpretation of the stochastic gravitational wave background signal detected by pulsar timing array experiments

S Vagnozzi - Journal of High Energy Astrophysics, 2023 - Elsevier
Various pulsar timing array (PTA) experiments (NANOGrav, EPTA, PPTA, CPTA, including
data from InPTA) very recently reported evidence for excess red common-spectrum signals …

Flat energy spectrum of primordial gravitational waves versus peaks and the NANOGrav 2023 observation

VK Oikonomou - Physical Review D, 2023 - APS
In this work we present several characteristic examples of theories of gravity and particle
physics scenarios that may yield an observable energy spectrum of stochastic primordial …

Effects of the axion through the Higgs portal on primordial gravitational waves during the electroweak breaking

VK Oikonomou - Physical Review D, 2023 - APS
We investigate the effects of short axion kination eras on the energy spectrum of the
primordial gravitational waves corresponding to modes that reenter the Hubble horizon at …

Constant-roll and primordial black holes in f (Q, T) gravity

K El Bourakadi, M Koussour, G Otalora… - Physics of the Dark …, 2023 - Elsevier
In this study, we investigate the consequence of the constant-roll condition and examine the
role of a chosen form of f (Q, T) gravity, given by f (Q, T)= α Q 2+ σ T, in the cosmological …

Inflationary dynamics and swampland criteria for modified Gauss-Bonnet gravity compatible with GW170817

SD Odintsov, VK Oikonomou, FP Fronimos - Physical Review D, 2023 - APS
In this article we present an alternative formalism for the inflationary phenomenology of
rescaled Einstein-Gauss-Bonnet models which are in agreement with the GW170817 event …

Implications of a scalar field interacting with the dark matter fluid on primordial gravitational waves

VK Oikonomou - Physical Review D, 2024 - APS
We consider the implications of a scalar field interacting with the dark matter fluid on the
energy spectrum of primordial gravitational waves. We choose an interaction type which …

A stiff pre-CMB era with a mildly blue-tilted tensor inflationary era can explain the 2023 NANOGrav signal

VK Oikonomou - arXiv preprint arXiv:2309.04850, 2023 - arxiv.org
We examine the effects of a stiff pre-recombination era on the present day's energy spectrum
of the primordial gravitational waves. If the background total equation of state parameter at …

Spontaneous scalarization of black holes in Gauss-Bonnet teleparallel gravity

S Bahamonde, DD Doneva, L Ducobu, C Pfeifer… - Physical Review D, 2023 - APS
In this paper, we find new scalarized black holes by coupling a scalar field with the Gauss-
Bonnet invariant in teleparallel gravity. The teleparallel formulation of this theory uses …

Observational constraints on Tachyon inflation and reheating in f (Q) gravity

KE Bourakadi, Z Sakhi, M Bennai - arXiv preprint arXiv:2302.11229, 2023 - arxiv.org
In this work we study one of the most appealing string theory-motivated models, we present
a tachyonic inflationary model in the recently proposed symmetric teleparallel framework …

Low-scale mirror standard model dark matter and its detection via gravitational waves and the Guitar Nebula

VK Oikonomou - Physical Review D, 2024 - APS
What if the dark matter sector is truly dark, self-interacting, and unreachable by terrestrial
experiments? How could we find hints of such dark sector if it is experimentally unreachable …