299 citations · 934 across the 26 of their papers we have counts for
20 papers · 1 filter
Reconstructing sign-switching dark energy histories: Scalar-field regularity, conditional potential comparison, and representative dynamics
Shahnawaz A. Adil, Özgür Akarsu, Mariam Bouhmadi-López +3
Phenomenologically similar sign-switching dark-energy histories need not have comparable scalar-field realizations. We reconstruct minimally coupled scalars with fixed kinetic sign…
Action-selected currents and a singular conservation closure in two-fluid energy--momentum-squared cosmology
Özgür Akarsu, Bilal Bulduk, Nihan Katırcı
In multi-fluid, matter-type gravity, the Bianchi identity constrains the divergence of the total effective stress tensor but does not, by itself, determine the currents assigned to…
Role of internal space correlations in the dynamics of a higher-dimensional Bianchi type-I universe: shear scalar and Hubble parameter perspectives
Nihan Katırcı
We investigate exact solutions of the Einstein field equations in higher-dimensional, spatially homogeneous Bianchi type-I spacetimes, introducing a real parameter that correla…
Unexplored regions in teleparallel gravity: Sign-changing dark energy density
Ozgur Akarsu, Bilal Bulduk, Antonio De Felice +2
While gravity has shown considerable potential in addressing cosmological tensions, we explore previously overlooked solution spaces that hold further promise. We examine th…
Equivalence of matter-type modified gravity theories to general relativity with nonminimal matter interaction
Özgür Akarsu, Mariam Bouhmadi-López, Nihan Katırcı +3
In this study, we first establish that gravity models incorporating matter-related terms, such as , , and , into the usu…
Weak field and slow motion limits in energy-momentum powered gravity
Ozgur Akarsu, A. Kazim Camlibel, Nihan Katirci +2
We explore the weak field and slow motion limits, Newtonian and Post-Newtonian limits, of the energy-momentum powered gravity (EMPG), viz., the energy-momentum squared gravity (EMS…
Dynamical analysis of logarithmic energy-momentum squared gravity
Giovanni Acquaviva, Nihan Katirci
We perform the dynamical system analysis of a cosmological model in the energy-momentum squared gravity (EMSG) of the form , which is known a…
CDM cosmology with a quiescent anisotropy in a higher dimensional steady state universe
Ozgur Akarsu, Tekin Dereli, Nihan Katirci
In this work, which follows a series of studies on the higher-dimensional steady state universe idea and prepared for Professor Tekin Dereli's Festschrift, we show the influence of…
Scalar field emulator via anisotropically deformed vacuum energy: Application to dark energy
Ozgur Akarsu, Nihan Katirci, Anjan A. Sen +1
We introduce a generalization of the usual vacuum energy, called `deformed vacuum energy', which yields anisotropic pressure whilst preserving zero inertial mass density. It couple…
Anisotropic massive Brans-Dicke gravity extension of the standard CDM model
Ozgur Akarsu, Nihan Katirci, Nese Ozdemir +1
We present an explicit detailed theoretical and observational investigation of an anisotropic massive Brans-Dicke (BD) gravity extension of the standard CDM model, wherein the e…
Cosmological implications of scale-independent energy-momentum squared gravity: Pseudo nonminimal interactions in dark matter and relativistic relics
Ozgur Akarsu, Nihan Katirci, Suresh Kumar +2
In this paper, we introduce a scale-independent energy-momentum squared gravity (EMSG) that allows different gravitational couplings for different types of sources, which may lead…
Constraint on energy-momentum squared gravity from neutron stars and its cosmological implications
Ozgur Akarsu, John D. Barrow, Sercan Çıkıntoğlu +2
Deviations from the predictions of general relativity due to energy-momentum squared gravity (EMSG) are expected to become pronounced in the high density cores of neutron stars. We…
Cosmic acceleration in dust only Universe via energy-momentum powered gravity
Ozgur Akarsu, Nihan Katirci, Suresh Kumar
We propose a modified theory of gravitation constructed by the addition of the term to the Einstein-Hilbert action, and elaborate a particular case $f(T_{μν}T^{μν…
Inflation and late time acceleration designed by Stueckelberg massive photon
Ozgur Akarsu, Metin Arik, Nihan Katirci
We present a mini review of the Stueckelberg mechanism, which was proposed to make the abelian gauge theories massive as an alternative to Higgs mechanism, within the framework of…
General solution of a cosmological model induced from higher dimensions using a kinematical constraint
Ozgur Akarsu, Tekin Dereli, Nihan Katirci +1
In a recent study Akarsu and Dereli (Gen. Relativ. Gravit. 45:1211, 2013) discussed the dynamical reduction of a higher dimensional cosmological model which is augmented by a kinem…
Accelerated expansion of the Universe a la the Stueckelberg mechanism
Ozgur Akarsu, Metin Arik, Nihan Katirci +1
We investigate a cosmological model in which the Stueckelberg fields are non-minimally coupled to the scalar curvature in a gauge invariant manner. We present not only a solution t…
gravity and Cardassian-like expansion as one of its consequences
N. Katirci, Mehmet Kavuk
We propose a new model of gravity where the Ricci scalar (R) in Einstein-Hilbert action is replaced by an arbitrary function of R and of the norm of energy-momentum tensor i.e., $f…
Electromagnetic Origin for Planck Mass and Dark Energy
Metin Arik, Nihan Katirci
The origin of dark energy remains to be one of the challenges of modern cosmology. We modify Jordan-Brans-Dicke theory using a vector field instead of a scalar field and theory bec…
Possible Connection between Dark Energy and Electromagnetic Interactions
Metin Arik, N. Katirci
This paper has been withdrawn by the authors. Please see [arXiv:1208.3224]. We investigate a model where dark energy is caused by the photon field coupling to gravitation. The cosm…
A Cosmological Exact Solution of Complex Jordan-Brans-Dicke Theory and its Phenomenological Implications
Metin Arık, Mehmet Calık, N. Katirci
When Brans-Dicke Theory is formulated in terms of the Jordan scalar field ϕ, dark energy is related to the mass of this field. We show that if ϕis taken to be a complex scalar fiel…