Related papers: Modified cosmology through Kaniadakis entropy
We consider perturbative modifications of the Friedmann equations in terms of energy density corresponding to modified theories of gravity proposed as an alternative route to comply with the observed accelerated expansion of the universe.…
Assuming that observers located inside the Universe measure a time flow which is different from the time appearing in the Friedmann-Lemaitre equation, and determining this time flow such that the Universe always appears flat to these…
The contemporary cosmic expansion is considered in the context of Modified Friedmann Dynamics (MOFD). We discuss some relativistic model exploring analogy to MOND modification of Newtonian dynamics. We argue that MOFD cosmologies can…
We explore the cosmological consequences of Modified Gravity (MOG), and find that it provides, using a minimal number of parameters, good fits to data, including CMB temperature anisotropy, galaxy power spectrum, and supernova…
Using modified gravity with non-linear terms of curvature, $R^2$ and $R^{(r +2)}$ (with $r$ being the positive real number and $R$ being the scalar curvature), cosmological scenario,beginning at the Planck scale, is obtained. Here, a…
We investigate the evolution of a universe with a decaying cosmological term (vacuum energy) that is assumed to be a function of the scale factor. In this model, while the cosmological term increases to the early universe, the radiation…
In this work we present a derivation of modified Raychaudhuri and Friedmann equations from a phenomenological model of quantum gravity based on the thermodynamics of spacetime. Starting from general gravitational equations of motion which…
Expansion dynamics of the Universe is one of the important subjects in modern cosmology. The dark energy equation of state determines this dynamics so that the Universe is in an accelerating phase. However, the dark matter can also affect…
Although big bang cosmology effectively models even the most puzzling observational data, it offers no insight into why the cosmological expansion should occur at all. In this paper it is suggested that a finite Universe poses particular…
A range of cosmological observations demonstrate an accelerated expansion of the Universe, and the most likely explanation of this phenomenon is a cosmological constant. Given the importance of understanding the underlying physics, it is…
We investigate the emergence of cosmic hysteresis in cyclic bouncing cosmologies within the framework of $f(R)$ modified gravity theories. Building upon previous studies that explored hysteresis phenomena in braneworld and…
A new expression to the total age of the Universe is derived in terms of the average deceleration parameter. This kinematic result holds regardless of the curvature of the universe as well as of the underlying gravity theory. It remains…
We provide a simple mathematical description of the exchange of energy between two fluids in an expanding Friedmann universe with zero spatial curvature. The evolution can be reduced to a single non-linear differential equation which we…
The matter creation model of Prigogine--G\'eh\'eniau--Gunzig--Nardone is revisited in terms of a redefined creation pressure which does not lead to irreversible adiabatic evolution at constant specific entropy. With the resulting freedom to…
Observations conducted over the last few decades show that the expansion of the Universe is accelerating. In the standard model of cosmology, this accelerated expansion is attributed to a dark energy in the form of a cosmological constant.…
We present a brief history of the construction of models of the universe, followed by calculations of quantitative characteristics of basic geometric and kinematic properties of the Standard Cosmological Model ($\Lambda$CDM). Using the…
Modern astrophysical and cosmological models are faced with two severe theoretical difficulties, that can be summarized as the dark energy and the dark matter problems. Relative to the former, it has been stated that cosmology has entered a…
We consider the cosmological application of a (variant of) relatively newly proposed model \cite{1609.06915} unifying inflation, dark energy, dark matter, and the Higgs mechanism. The model was originally defined using additional…
We consider the scenario where our observable universe is devised as a dynamical four-dimensional hypersurface embedded in a five-dimensional bulk spacetime, with a large extra dimension, which is the {\it generalization of the flat FRW…
We develop a cosmological model based on action-dependent Lagrangian theories. The main feature here is the nonconservation of the energy momentum tensor due to the nontrivial geometrical construction of the theory. We provide the basic set…