Three different approaches show that, contrary to a longstanding conviction older than 160 years, the advance of Mercury perihelion can be achieved in Newtonian gravity with a very high precision by correctly analysing the situation without neglecting Mercury’s mass. General relativity remains more precise than Newtonian physics, but Newtonian framework is more powerful than researchers and astronomers

In this paper, the thermodynamics and the stability of horizon of the charged AdS black hole surrounded by quintessence and cloud of strings in d-dimensional spacetime are studied via the scalar field scattering and the charged particle absorption. The cosmological constant is interpreted as the thermodynamic pressure in the black hole. During the study, we consider the case where the energy of the

The implications of thermal geometries on Brane-World black hole (consisting of cosmological and dark matter effects) will be investigated by extracting the stability conditions (small and large roots) and divergences. To achieve this, we develop the temperature and heat capacity with respect to horizon radius, cosmological and dark matter parameters, respectively, which help in analyzing the small

We consider a cosmological model with dark matter in the form of ∼10−12M⊙ primordial black holes in dense weakly relativistic clusters with masses 18–560M⊙. It is shown that during the multiple collisions of the black holes the ∼10% of the initial cluster mass can be transformed into gravitational waves in the time interval from recombination to the redshifts z≥10. At the recombination epoch, the density

Quantum-effective gravity must lead to a regularized cosmology and thereby by itself source and regulate the high energy inflaton fields required for an appropriate inflationary beginning of the Universe. Pursuing this premise, we involve in the generic code of extended theories of gravity in conceiving semi-classical imprinting of quantum effects into gravitation. Hence, we prescribe a general semi-classical

We study the gravitational waves phenomena for generalized Chaplygin gas, variable modified Chaplygin gas and some parametrizations of dark energy models. Motivated by their works, here we consider the Friedmann–Robertson–Walker (FRW) model of the non-flat Universe in the presence of dark matter with dark energy and we investigate the gravitational waves phenomena for some other candidates of dark

Purely kinetic k-essence models have been shown in the literature to be a field theory equivalent of barotropic fluid models of dark energy or dark matter–dark energy unification. In the modeling framework where the speed of sound squared of a barotropic fluid is modeled as a function of its Equation of State parameter, a systematic procedure of obtaining the Lagrangian density of an equivalent purely

Improvement of the classical gravity with the running gravitational coupling obtained from asymptotically safe gravity, is a good way of considering the effects of quantum gravity. This is usually done for metric theories of gravity. Here we investigate the effects of such an improvement for pure affine theories of gravity. To motivate the approach, we first consider the effects of quantum improvement

The matter–antimatter asymmetry through baryogenesis (and generalized baryogenesis interaction) mechanism for well-known models of f(R,G) gravity (where R,G represent the Ricci scalar curvature and Gauss–Bonnet topological invariant) and f(G,T) (T denotes the trace of the energy momentum tensor) is being examined. This mechanism is based on the charge-parity (CP) violating interaction between the derivative

We consider a non-canonic field in the context of Starobinsky inflation. We work in Einstein-frame. In this frame, the gravitational part of the action is equivalent to the Hilbert–Einstein action, plus a scalar field called scalaron. We investigate a model with a heavy scalaron trapped at the effective potential minimum, where its fluctuations are negligible. To be more explicit, we consider a Dirac–Born–Infeld

We present here a quantitative estimate of the impact of uncertainties of astrophysical nature on the determination of the dark matter distribution within our Galaxy, the Milky Way. Based on an update of a previous analysis, this work is motivated by recent new determinations of astrophysical quantities of relevance – such as the Galactic parameters (R0, V0) – from the GRAVITY collaboration and the

In the present paper, we investigate the required anisotropy of an exact regular Bardeen black hole characterized by its mass M and the nonlinear parameter β in anti-de sitter spacetime with a static anisotropic matter field. We also show that the relative pressure anisotropy, equation of state and the pressure depends on the radial coordinate, reflecting the required anisotropy for Bardeen black hole

The multi-messenger observation of GW170817 enabled the first historic measurement of the Hubble constant via a standard siren, so-called in analogy to standard candles that enabled the measurement of the luminosity distance versus redshift relationship at small redshift. In the next decades, third-generation observatories are expected to detect hundreds to thousand of gravitational wave events from

After reionisation, the 21 cm emission line of neutral hydrogen within galaxies provides a tracer of dark matter. Next-generation intensity mapping surveys, with the SKA and other radio telescopes, will cover large sky areas and a wide range of redshifts, facilitating their use as probes of primordial non-Gaussianity. Previous works have shown that the bispectrum can achieve tight constraints on primordial

The observation of strongly lensed Type Ia supernovae enables both the luminosity and angular diameter distance to a source to be measured simultaneously using a single observation. This feature can be used to measure the distance duality parameter η(z) without relying on multiple datasets and cosmological assumptions to reconstruct the relation between angular and luminosity distances. In this paper

We test the cosmological implications of a varying absolute magnitude of Type Ia supernovae using the Pantheon compilation, by reconstructing different phenomenological approaches that could justify a varying absolute magnitude, but also approaches based on cosmic voids, modified gravity models and a binning scheme. In all the cases considered in this work, we find good agreement with the expected

We consider a specific dark energy model, which only includes the Lagrangian up to the cubic order in terms of the vector field self-interactions in the generalized Proca theory. We examine the cosmological parameters in the model by using the data sets of CMB and CMB+HST, respectively. In particular, the Hubble constant is found to be H0=71.80−0.72+1.07 (72.48−0.60+0.72) kms−1Mpc−1 at 68% C.L. with

In this paper, we will consider cosmological implications of the Maxwell theory coupled to a non-local U(1)-symmetric term. It is well-known that the theory in flat space–time, reduces to the Proca theory. However, it will be shown that in curved space–time the resulting theory will differ from the coupled Einstein–Proca system. The cosmological perturbations on top of the de Sitter space–time is also

In this article, we have investigated the role of bulk viscosity to study the accelerated expansion of the universe in the framework of modified f(Q) gravity. The gravitational action in this modified gravity theory has the form f(Q), where Q denote the non-metricity scalar. In the present manuscript, we have considered a bulk viscous matter-dominated cosmological model with the bulk viscosity coefficient

We assume a dark U(1)D symmetric hidden sector and explore its possible content such that neutrino mass and Dark Matter are generated through the scotogenic mechanism. The hidden sector is considered analogue to the Standard Model, namely the charge assignment of hidden fermions is chiral and anomaly-free. Moreover, U(1)D is assumed broken by an only Higgs singlet that also generates masses to all

In the present work we present, for the first time ever, the exact configuration integral entering the partition function Z that allows for a statistical mechanics treatment of galactic clustering. Thus, the general distribution function and the general clustering parameter for point mass systems is obtained from a grand canonical ensemble discussion. Such distribution is also approximated starting

We perform correct and reasonable cosmological constraints on the newly proposed 4D Gauss–Bonnet gravity. Using the joint constraint from cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers and redshift space distortions, we obtain, so far, the strongest constraint α̃=(1.2±5.2)×10−17, namely α=(2.69±11.67)×1048 eV−2, among various observational limitations

We use a combination of observational data in order to reconstruct the free function of f(T) gravity in a model-independent manner. Starting from the data-driven determined dark-energy equation-of-state parameter we are able to reconstruct the f(T) form. The obtained function is consistent with the standard ΛCDM cosmology within 1σ confidence level, however the best-fit value experiences oscillatory

We investigate Euclidean wormholes in Gauss–Bonnet-dilaton gravity to explain the creation of the universe from nothing. We considered two types of dilaton couplings (i.e., the string-inspired model and the Gaussian model) and we obtained qualitatively similar results. There can exist Euclidean wormholes that explain the possible origin of our universe, where the dilaton field is located over the barrier

With the recent data from the first year of the Dark Energy Survey (DES Y1), we attempt to probe whether there is new physics beyond the standard cosmology and to reconcile the σ8 tension between the DES Y1 and Planck datasets in three alternative cosmological models. Combining the galaxy clustering and weak gravitational lensing data from the DES Y1 with other cosmological observations including cosmic

We pioneer the black hole mass gap as a powerful new tool for constraining new particles. A new particle that couples to the Standard Model – such as an axion – acts as an additional source of loss in the cores of population-III stars, suppressing mass lost due to winds and quenching the pair-instability. This results in heavier astrophysical black holes. As an example, using stellar simulations we

In an alternative dark matter scenario, it is assumed that there exist two species of dark matter: a heavy dark matter particle (HDM) with the mass of O(TeV) which is generated in early universe and a lighter dark matter particle (LDM) which is a relativistic product due to the decay of HDM. HDMs, captured by the earth, decay to high energy LDMs, and these particles can be measured by km3 neutrino

In this paper, we study a triad of inhomogeneous scalar fields, known as ”solid”, as a source of homogeneous but anisotropic dark energy. By using a dynamical system approach, we find that anisotropic accelerated solutions can be realized as attractor points for suitable choices of the parameters of the model. We complement the dynamical analysis with a numerical solution whose initial conditions are

Within the framework of Unimodular Gravity, we consider non-gravitational interactions between dark matter and dark energy. Particularly, we describe such interactions in the dark sector by considering diffusion models that couple the cold dark matter fluid with the dark energy component, where the latter has the form of a variable cosmological “constant”. For the first time, we solve the cosmological

In this work, we explore the phenomenon of cosmic evolution using curved FLRW space–time bounded by apparent horizon with a specific holographic cut-off. To this end, we use the framework of Rastall gravity (RG) and universe is assumed to be consists of interacting/ non-interacting dark energy (DE) and dark matter (DM). In both scenarios, we evaluate exact solutions of the dynamical equations and constraint

In this paper, we investigate the behavior of charged anisotropic solutions for a static sphere in the background of self-interacting Brans–Dicke theory. The spherical solutions are devised from known isotropic distributions by adding a source in the action. Deformations are induced in temporal and radial metric functions to decompose the field equations into two sets. We employ the metric potentials

This article discusses a dark energy cosmological model in the standard theory of gravity - general relativity with a broad scalar field as a source. Exact solutions of Einstein’s field equations are derived by considering a particular form of deceleration parameter q, which shows a smooth transition from decelerated to accelerated phase in the evolution of the universe. The external datasets such

We inspect the possibility that neutron star interiors are a mixture of ordinary matter and mirror dark matter. This is a scenario that can be naturally envisaged according to well studied accretion mechanisms, including the Bondi–Hoyle one. We show that the inclusion of mirror dark matter in neutron star models lowers the maximum neutron star mass for a given equation of state, and that it decreases

In this work we shall study the implications of a subclass of E-models cosmological attractors, namely of a-attractors, on hydrodynamically stable slowly rotating neutron stars. Specifically, we shall present the Jordan frame theory of the a-attractors, and by using a conformal transformation we shall derive the Einstein frame theory. We discuss the inflationary context of a-attractors in order to

In this paper we have assumed a weak-field regime to explore the gravitational lensed photons in a 4 dimensional Einstein–Gauss–Bonnet gravity, which is very much in the limelight these days. The investigation is conducted in three distinct paradigms: uniform plasma, singular isothermal sphere and a non-singular isothermal sphere. The lensing angle associated with the distribution factor of the medium

Given an anisotropic fluid source, we determine in closed forms, upon solving the field equations of general relativity (GR) and teleparallel gravity (TEGR) coupled to a cosmological constant, cylindrically symmetric four-dimensional cosmological rotating wormholes, satisfying all local energy conditions, and cosmological rotating solutions with two axes of symmetry at finite proper distance. These

Einstein–Gauss–Bonnet (EGB) model is recently restudied in order to analyze new consequences in gravitation, modifying appropriately the Einstein–Hilbert action. The consequences in EGB cosmology are mainly geometric, with higher order values in the Hubble parameter. In this vein this paper is devoted to contribute with extra evidences about its pros and cons of the model from a cosmological point

We obtain a scaling relation for spherically symmetric k-essence scalar fields ϕ(r,t) for an inhomogeneous cosmology with the Lemaitre–Tolman–Bondi (LTB) metric. We show that this scaling relation reduces to the known relation for a homogeneous cosmology when the LTB metric reduces to the Friedmann–Lemaitre–Robertson–Walker (FLRW) metric under certain identifications of the metric functions. A k-essence

In this paper, we study the geodesic deviation equation (GDE) within the context of the Brans–Dicke (BD) theory in D dimensions. Then, we restrict our attention to the GDE for the fundamental observers and null vector field past directed. Concerning the latter, in order to apply the retrieved GDE for the cosmological models as well as examining exact solutions, we study some cosmological models in

This paper is devoted to investigating the oscillating universe in f(G,T) gravity, where G is the Gauss–Bonnet term and T is the trace of energy–momentum tensor. Purpose of this paper is twofold: First, we consider a Gauss–Bonnet cosmological model with logarithmic trace term. We explore the possibility of bouncing solutions by choosing a well-known equation of state parameter. Secondly, we consider

Quantum cosmology with quintom dark energy model has been investigated in the present work using symmetry analysis of the underlying physical system. In the background of the flat FLRW model quintom cosmological model has been studied using Noether symmetry and appropriate conserved charge is obtained. The Wheeler–DeWitt (WD) equation is constructed on the minisuperspace and solutions are obtained

Low energy limits of string theory indicated that the standard gravity action should be modified to include higher-order curvature terms, in the form of dimensionally continued Gauss–Bonnet densities. If one includes only quadratic curvature terms then the resulting theory is Einstein–Gauss–Bonnet (EGB) gravity valid only in D>4 dimensions. Recently there has been a surge of interest in regularizing

This work is devoted to the recently introduced Einstein–Gauss–Bonnet gravity in four dimensions. This theory can bypass Lovelock’s theorem and avoids Ostrogradsky instability. The integrated part of this theory is the GB term which gives rise to a non-trivial contribution to the gravitational dynamics in the limit D→4. Our main interest is to explore a class of static, spherically symmetric compact

Gravitational wave detection from binary black hole (BBH) inspirals has become routine thanks to the LIGO/Virgo interferometers. The nature of these black holes remains uncertain. We study here the spin distributions of LIGO/Virgo black holes from the first catalogue GWTC-1 and the first four published BBH events from run O3. We compute the Bayes evidence for several independent priors: flat, isotropic

In the present work, we extend and generalize our previous work regarding the scale dependence applied to black holes in the presence of non-linear electrodynamics (Rincón et al., 2017). The starting point for this study is the Einstein-power-Maxwell theory with a vanishing cosmological constant in (3+1) dimensions, assuming a scale dependence of both the gravitational and the electromagnetic coupling

A regularized four-dimensional Einstein–Gauss–Bonnet model has been recently proposed in Glavan and Lin (2020). It was claimed that the approach bypasses the Lovelock theorem. In this approach the four-dimensional solution is constructed through dimensional regularization by taking the limit D→4. The consistent formulation of the corresponding four-dimensional theory with broken diffeomorphism invariance

We extended the modified Lemaitre–Tolman model (Peirani and de Freitas Pacheco, 2006; Peirani and de Freitas Pacheco, 2008) taking into account the effect of angular momentum and dynamical friction. The inclusion of these quantities in the equation of motion modifies the evolution of a perturbation, initially moving with the Hubble flow. Solving the equation of motions we got the relationships between

In this paper, we have constructed the cosmological model of the universe in interacting two-fluid environment i.e. dark matter and HDE models by choosing the interaction between them should be a function with unit of inverse of cosmic time which is the form of Q=3δHρm (where δ is the coupling constant). In order to construct the model, Hypersurface-homogeneous space–time is considered with a constant

We are living in a golden age for experimental cosmology. New experiments with high accuracy precision are been used to constrain proposals of several theories of gravity, as it has been never done before. However, important roles to constrain new theories of gravity in a theoretical perspective are the energy conditions. Throughout this work, we carefully constrained some free parameters of two different

In this work we model two non-linear directly interacting scenarios in dark sector of the universe with the dimensionless parameter α and β, which dominate the energy exchange between dark energy and dark matter. The central goal of this investigation is to research the interacting model and discuss the cosmological implications based on the current observational datasets. The class of the interaction

Considering the entropic force on the holographic Hubble horizon of the universe which carries a Bekenstein–Hawking entropy and temperature leads to the entropic force cosmology, and it assumes that the entropic force is responsible from the increase of entropy and accelerated expansion of the universe as a source of cosmological constant. This assumption naturally solves the cosmological constant

In this paper, we discuss the cosmic evolution of the anisotropic and spatially homogeneous Kantowski–Sachs universe with Renyi holographic dark energy in the background of general relativity. In order to find a solution of the field equations we have considered a relation between the metric potentials of the model. Cosmological aspects of the dynamical parameters corresponding to our dark energy model

Several attempts have been made in the past decades to search for the true ground state of the dense matter at sufficiently large densities and low temperatures via compact astrophysical objects. Focusing on strange stars, we derive the hydrostatic equilibrium assuming a maximally symmetric phase of homogeneous superconducting quark matter called the color-flavor-locked (CFL) phase in the background

We study the interaction, in general curved spacetime, between a spinor and a scalar field describing dark energy; the so-called DEν model in curved space. The dominant term is the dimension 5 operator, which results in different energy shifts for the neutrino states: an Aharonov–Bohm-like effect. We study the phenomenology of this term and make observational predictions to detect dark energy interactions

We explore the mimetic gravity formulation with the inclusion of a scalar field potential namely, V(ϕ). However, we are not considering any a priori specific form this term. By means of the Chevallier–Polarski–Linder parametrization for the parameter state of the fluid we can construct an explicit function for such potential in terms of the cosmological redshift and obtain analytical solutions in the

We demonstrate that Kerr/CFT duality can be extended to rotating charged black hole solution surrounded by quintessence in Rastall gravity. Since Rastall gravity can be considered as F(R,T)=R+βT theory with the addition of a matter term, so the gravitational Lagrangian is resemblant to Einstein general relativity. In fact, the resulting central term is coincident to the central term in the general

We consider the evolution of traversable wormhole geometries in the inflationary, radiation – and matter – dominated eras, and dynamic wormholes with a traceless energy–momentum tensor (EMT), within the recently proposed pole dark energy model. We show that the evolving radiation – and matter – dominated wormhole space times satisfy the null energy condition (NEC), but possess negative energy densities

In this paper, the new formalism of thermodynamic geometry proposed in Hosseini Mansoori and Mirza (2019) is employed in investigating phase transition points and the critical behavior of a Gauss–Bonnet-AdS black hole in four dimensional spacetime. In this regard, extrinsic and intrinsic curvatures of a certain kind of hypersurface immersed in the thermodynamic manifold contain information about s

I propose a new model of preinflation, where the universe suffers a transition from an initial stable state [such that the universe is initially at the minimum of a ϕ-quartic potential: V(ϕ)∼ϕ4], to an unstable evolving state that drives the initial accelerated expansion. Using Relativistic Quantum Geometry (RQG), I demonstrate that back-reaction produced by the inflaton field fluctuations should be

By the use of homotopy perturbation method-Padé (HPM-Padé) technique, a new analytical approximation of luminosity distance in the flat universe is proposed, which has the advantage of significant improvement for accuracy in approximating luminosity distance over cosmological redshift range within 0≤z≤2.5. Then we confront the analytical expression of luminosity distance that is obtained by our new