95 citations · 634 across the 27 of their papers we have counts for
27 papers
Towards Model Agnostic Gravity Inflation
V. K. Oikonomou
In this work we construct a formalism that can reveal the general characteristics of classes of viable inflationary theories. The assumptions we make is that the slow-roll e…
Rescaled Einstein-Gauss-Bonnet Gravity Inflation
V. K. Oikonomou, Ardit Gkioni, Iason Sdranis +2
We study the inflationary phenomenology of a rescaled Einstein-Gauss-Bonnet gravity. In this framework, the gravitational constant of the Einstein-Hilbert term is rescaled due to e…
Phenomenology of Axionic Static Neutron Stars with Masses in the Mass-Gap Region
V. K. Oikonomou
In this work we consider an axionic scalar-tensor theory of gravity and its effects on static neutron stars. The axionic theory is considered in the regime in which the axion oscil…
Red or Blue Tensor Spectrum from GW170817-compatible Einstein-Gauss-Bonnet Theory: A Detailed Analysis
V. K. Oikonomou, Pyotr Tsyba, Olga Razina
In this work we shall prove that the tensor spectral index of the primordial tensor perturbations for GW170817-compatible Einstein-Gauss-Bonnet theories, takes the approximate simp…
Primordial Cosmology of an Emergent-like Universe from Modified Gravity: Reconstruction and Phenomenology Optimization with a Genetic Algorithm
V. K. Oikonomou, Gregory K. Kafanelis
In this work we consider the realization of a variant emergent Universe scenario in the context of gravity. We use well-known reconstruction techniques existing in the liter…
Flat Energy Spectrum of Primordial Gravitational Waves vs Peaks and the NANOGrav 2023 Observation
V. K. Oikonomou
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…
Swampland Criteria and Constraints on Inflation in a Gravity Theory
V. K. Oikonomou, Konstantinos-Rafail Revis, Ilias C. Papadimitriou +1
In this paper, we worked in the framework of an inflationary theory, in the presence of a canonical scalar field. More specifically, the gravity. The valu…
Static Neutron Stars Perspective of Quadratic and Induced Inflationary Attractor Scalar-tensor Theories
V. K. Oikonomou
This study focuses on the static neutron star perspective for two types of cosmological inflationary attractor theories, namely the induced inflationary attractors and the quadrati…
Gravity Effects on the Kinetic Axion Phase Space
V. K. Oikonomou
In this work we consider the effect of an term on the kinetic misalignment axion theory. By using the slow-roll assumptions during inflation and the field equations, we const…
Dissimilar Donuts in the Sky? Effects of a Pressure Singularity on the Circular Photon Orbits and Shadow of a Cosmological Black Hole
S. D. Odintsov, V. K. Oikonomou
The black hole observations obtained so far indicate one thing: similar "donuts" exist in the sky. But what if some of the observed black hole shadows that will obtained in the fut…
Bottom-Up Reconstruction of Viable GW170817 Compatible Einstein-Gauss-Bonnet Theories
V. K. Oikonomou, P. D. Katzanis, Ilias C. Papadimitriou
In this work we shall use a bottom-up approach for obtaining viable inflationary Einstein-Gauss-Bonnet models which are also compatible with the GW170817 event. Specifically, we sh…
Did the Universe Experienced a Pressure non-Crushing Type Cosmological Singularity in the Recent Past?
S. D. Odintsov, V. K. Oikonomou
In the recent literature it has been shown that the tension may be eliminated if an abrupt physics transition changed the Cepheid parameters in the near past of the Universe,…
Maximum Baryon Masses for Static Neutron Stars in Gravity
A. V. Astashenok, S. Capozziello, S. D. Odintsov +1
We investigate the upper mass limit predictions of the baryonic mass for static neutron stars in the context of gravity. We use the most popular gravity model, namely…
On the Occurrence of Finite-time Singularities in Swampland-related Quintessence Dark Energy Models
V. K. Oikonomou, Achilles Gitsis, Maria Mitrou
In this work we focus on the phase space singularities of interactive quintessence model in the presence of matter fluid. This model is related to swampland studies, that the outco…
A Refined Einstein-Gauss-Bonnet Inflationary Theoretical Framework
V. K. Oikonomou
We provide a refined and much more simplified Einstein-Gauss-Bonnet inflationary theoretical framework, which is compatible with the GW170817 observational constraints on the gravi…
Universal Inflationary Attractors Implications on Static Neutron Stars
V. K. Oikonomou
We study static neutron stars in the context of a class of non-minimally coupled inflationary potentials, the universal attractors. Universal attractors are known to generate a via…
Non-minimally Coupled Scalar -Inflation Dynamics
V. K. Oikonomou
In this work we shall study -inflation theories with non-minimal coupling of the scalar field to gravity, in the presence of only a higher order kinetic term of the form $\sim \…
A Nearly Massless Graviton in Einstein-Gauss-Bonnet Inflation with Linear Coupling Implies Constant-roll for the Scalar Field
V. K. Oikonomou, F. P. Fronimos
The striking GW170817 event indicated that the graviton is nearly massless, since the gamma rays emitted from the two neutron stars merging arrived almost simultaneously with the g…
Rectifying an Inconsistency in Gravity Inflation
V. K. Oikonomou
In this letter we shall provide a formal derivation of the inflationary slow-roll indices for gravity from the power spectrum without the condition , frequently u…
Canonical Scalar Field Inflation with a Woods-Saxon Potential
V. K. Oikonomou, N. Th. Chatzarakis
This paper focuses on the realization of an inflationary model from a canonical scalar field theory with a Woods-Saxon potential, in the slow-roll approximation. Our analysis indic…
Autonomous Dynamical System of Einstein-Gauss-Bonnet Cosmologies
N. Chatzarakis, V. K. Oikonomou
In this paper, we study the phase space of cosmological models in the context of Einstein-Gauss-Bonnet theory. More specifically, we consider a generalized dynamical system that en…
Effects of Spatial Curvature on the Gravity Phase Space: no Inflationary Attractor?
S. D Odintsov, V. K. Oikonomou
In this paper we study the effects of spatial curvature of the metric on the phase space of vacuum gravity. Particularly, we appropriately choose the variables of the dynami…
Cosmological Fluids with Logarithmic Equation of State
S. D. Odintsov, V. K. Oikonomou, A. V. Timoshkin +2
We investigate the cosmological applications of fluids having an equation of state which is the analog to the one related to the isotropic deformation of crystalline solids, that i…
Autonomous Dynamical System Description of de Sitter Evolution in Scalar Assisted Gravity
K. Kleidis, V. K. Oikonomou
In this letter we will study the cosmological dynamical system of an gravity in the presence of a canonical scalar field with an exponential potential, by constructing t…