217 citations · 2.3k across the 54 of their papers we have counts for
42 papers
Adiabatic Perturbations in GW170817-Compatible Einstein-Gauss-Bonnet Inflation
S. D. Odintsov, V. K. Oikonomou
We study the adiabaticity of the cosmological perturbations in the context of inflationary Einstein-Gauss-Bonnet theories. We focus on viable inflationary Einstein-Gauss-Bonnet the…
ACT Data and Positive Running of the Spectral Index for Scalar Theory and Modified Gravity
S. D. Odintsov, V. K. Oikonomou
In this work we address the possibility of having a positive running of the spectral index in inflationary theories. The recent ACT data indicate mildly that the running of the spe…
Is Phantom Divide Crossing in General Relativity Completely Impossible? Shortcomings in canonical and minimally coupled scalar field and Possible Solutions in -essence Models
Shin'ichi Nojiri, S. D. Odintsov, V. K. Oikonomou
General relativity has its successes at the local astrophysical level, however, it seems to be insufficient in describing the Universe at large scales. In this work we investigate…
Apparent Phantom Crossing in Gauss-Bonnet Gravity
Shin'ichi Nojiri, Sergei D. Odintsov, V. K Oikonomou
The recent observations of the Dark Energy Spectroscopic Instrument (DESI) indicated the possibility that the dark energy equation of state parameter might change from t…
Revisiting Einstein-Gauss-Bonnet Theories after GW170817
V. K. Oikonomou
In this work we study the inflationary framework of Einstein-Gauss-Bonnet theories which produce a primordial gravitational wave speed that respects the constraint imposed by the G…
The Necessity of Multi-Band Observations of the Stochastic Gravitational Wave Background
S. D. Odintsov, V. K. Oikonomou
In this work we highlight an important perspective for the complete understanding of the stochastic gravitational background structure. The stochastic gravitational wave background…
Implications of a Scalar Field Interacting with the Dark Matter Fluid on the Primordial Gravitational Waves
V. K. Oikonomou
We consider the implications of a scalar field interacting with the dark matter fluid on the energy spectrum of the primordial gravitational waves. We choose an interaction type wh…
Einstein-Gauss-Bonnet Cosmological Theories at Reheating and at the End of the Inflationary Era
V. K. Oikonomou, Pyotr Tsyba, Olga Razina
In this work we study the GW170817-compatible Einstein-Gauss-Bonnet theories during the reheating and the end of inflationary era. Given the scalar field potential which can…
Recent Advances on Inflation
S. D. Odintsov, V. K. Oikonomou, I. Giannakoudi +2
We review recent trends on inflationary dynamics in the context of viable modified gravity theories. After providing a general overview of the inflationary paradigm emphasizing on…
Compact Stars with Dark Energy in General Relativity and Modified Gravity
Artyom V. Astashenok, Sergey D. Odintsov, Vasilis K. Oikonomou
We investigate realistic models of compact objects, focusing on neutron and strange stars, composed by dense matter and dark energy in the form of a simple fluid or scalar field in…
Chandrasekhar Mass Limit of White Dwarfs in Modified Gravity
Artyom V. Astashenok, Sergey D. Odintsov, Vasilis Oikonomou
We investigate the Chandrasekhar mass limit for white dwarfs in various models of gravity. Two equations of state for stellar matter are used: simple relativistic polytropic…
Maximal Masses of White Dwarfs for Polytropes in Gravity and Theoretical Constraints
Artyom V. Astashenok, Sergey D. Odintsov, Vasilis K. Oikonomou
We examine the Chandrasekhar limit for white dwarfs in gravity, with a simple polytropic equation of state describing stellar matter. We use the most popular gravity…
Primordial Gravitational Waves Predictions for GW170817-compatible Einstein-Gauss-Bonnet Theory
V. K. Oikonomou
In this work we shall calculate in detail the effect of an GW170817-compatible Einstein-Gauss-Bonnet theory on the energy spectrum of the primordial gravitational waves. The spectr…
Amplification of Primordial Gravitational Waves by a Geometrically Driven non-canonical Reheating Era
S. D. Odintsov, V. K. Oikonomou
In order to describe inflation in general relativity, scalar fields must inevitably be used, with all the setbacks of that description. On the other hand, gravity and other…
Generalized Horndeski-Like Einstein Gauss-Bonnet Inflation with Massless Primordial Gravitons
V. K. Oikonomou, F. P. Fronimos
In this work we shall introduce a theoretical framework comprised by a non-minimal coupled canonical scalar field, a non-minimal coupling to the Gauss-Bonnet invariant and a non-mi…
Causal Limit of Neutron Star Maximum Mass in Gravity in View of GW190814
A. V. Astashenok, S. Capozziello, S. D. Odintsov +1
We investigate the causal limit of maximum mass for stars in the framework of gravity. We choose a causal equation of state, with variable speed of sound, and with the transi…
Neutron Stars Phenomenology with Scalar-tensor Inflationary Attractors
S. D. Odintsov, V. K. Oikonomou
In this work we shall study the implications of a subclass of -models cosmological attractors, namely of -attractors, on hydrodynamically stable slowly rotating neutron stars…
Dark Energy and Cosmological Horizon Thermal Effects
Artyom V. Astashenok, Sergei D. Odintsov, Vasilis K. Oikonomou
We investigate various dark energy models by taking into account the thermal effects induced from Hawking radiation on the apparent horizon of the Universe, for example near a fini…
GW170817-compatible Constant-roll Einstein-Gauss-Bonnet Inflation and Non-Gaussianities
S. D. Odintsov, V. K. Oikonomou, F. P. Fronimos +1
In this paper we investigate the inflationary phenomenology of an Einstein-Gauss-Bonnet theory compatible with the GW170817 event, by imposing the constant-roll evolution on the sc…
Extended Gravity Description for the GW190814 Supermassive Neutron Star
Artyom V. Astashenok, Salvatore Capozziello, Sergei D. Odintsov +1
Very recently a compact object with a mass in the range has been discovered via gravitational waves detection of a compact binary coalescence. The mass of t…
Non-Minimally Coupled Einstein Gauss Bonnet Inflation Phenomenology in View of GW170817
S. D. Odintsov, V. K. Oikonomou, F. P. Fronimos
We study the inflationary phenomenology of a non-minimally coupled Einstein Gauss-Bonnet gravity theory, in the presence of a scalar potential, under the condition that the gravita…
Reviving non-Minimal Horndeski-like Theories after GW170817: Kinetic Coupling Corrected Einstein-Gauss-Bonnet Inflation
V. K. Oikonomou, F. P. Fronimos
After the recent GW170817 event of the two neutron stars merging, many string corrected cosmological theories confronted the non-viability peril. This was due to the fact that most…
Rectifying Einstein-Gauss-Bonnet Inflation in View of GW170817
S. D. Odintsov, V. K. Oikonomou, F. P. Fronimos
In this work we introduce a new theoretical framework for Einstein-Gauss-Bonnet theories of gravity, which results to particularly elegant, functionally simple and transparent grav…
Inflationary Phenomenology of Einstein Gauss-Bonnet Gravity Compatible with GW170817
S. D. Odintsov, V. K. Oikonomou
In this work we shall study Einstein Gauss-Bonnet theories and we investigate when these can have their gravitational wave speed equal to the speed of light, which is unity in natu…