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Phase transitions can play an important role in the cosmological constant problem, allowing the underlying vacuum energy, and therefore the value of the cosmological constant, to change. Deep within the core of neutron stars, the local…

General Relativity and Quantum Cosmology · Physics 2025-02-03 Giulia Ventagli , Pedro G. S. Fernandes , Andrea Maselli , Antonio Padilla , Thomas P. Sotiriou

In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant…

Astrophysics · Physics 2007-05-23 G. V. Kraniotis , S. B. Whitehouse

In this paper, we explore the properties of white dwarfs with the modified TOV equation in Einstein-$\Lambda$ gravity, the equilibrium configurations predict a maximum mass limit for white dwarfs same as the Chandrasekhar limit when we…

General Relativity and Quantum Cosmology · Physics 2019-02-27 H. L. Liu , G. L. Lü

The concept of deformation of Riemannian geometry is reviewed, with applications to gravitation and cosmology. Starting with an analysis of the cosmological constant problem, it is shown that space-times are deformable in the sense of local…

General Relativity and Quantum Cosmology · Physics 2015-05-28 M. D. Maia

We generalize the Tolman-Oppenheimer-Volkoff equations for space-times endowed with a Weyssenhoff like torsion field in the Einstein-Cartan theory. The new set of structure equations clearly show how the presence of torsion affects the…

General Relativity and Quantum Cosmology · Physics 2019-10-18 Paulo Luz , Sante Carloni

There are at least two cosmological constants calling for explanation. The first one describes the quasi-de Sitter inflation in the early universe, and the second describes the current acceleration of the universe associated with dark…

High Energy Physics - Theory · Physics 2024-05-01 Igor Volovich

Recent cosmological observations suggest the existence of a positive cosmological constant $\Lambda$ with the magnitude $\Lambda(G\hbar/c^3) \approx 10^{-123}$. This review discusses several aspects of the cosmological constant both from…

High Energy Physics - Theory · Physics 2008-11-26 T. Padmanabhan

We derive new limits on the value of the cosmological constant, $\Lambda$, based on the Einstein bending of light by systems where the lens is a distant galaxy or a cluster of galaxies. We use an amended lens equation in which the…

Astrophysics · Physics 2009-11-13 Mustapha Ishak , Wolfgang Rindler , Jason Dossett , Jacob Moldenhauer , Chris Allison

The properties of a star with constant positive energy density inside (as for the Schwarzschild interior geometry) and a negative pressure are investigated, using a static conformally flat spacetime. Because of the negative pressure, the…

General Relativity and Quantum Cosmology · Physics 2025-04-08 Hristu Culetu

General properties of neutron stars are briefly reviewed with an emphasis on the indispensability of general relativity in our understanding of these fascinating objects. In Newtonian gravity the pressure within a star merely plays the role…

High Energy Astrophysical Phenomena · Physics 2017-03-02 K. Yavuz Ekşi

We investigate some models of compact objects in the general relativity theory with cosmological constant $\Lambda$, based on two density profiles, one of them attributed to Stewart and the other one to Durgapal and Bannerji, proposed in…

General Relativity and Quantum Cosmology · Physics 2021-05-12 L. S. M. Veneroni , A. Braz , M. F. A. da Silva

In this paper we use and extend the results present in \cite{1,2,3,4} and in particular in \cite{4} to obtain a statistical description of the cosmological constant in a cosmological de Sitter universe in terms of massless excitations with…

General Relativity and Quantum Cosmology · Physics 2018-10-18 Stefano Viaggiu

A higher value of Hubble constant has been obtained from measurements with nearby Type Ia supernovae, than that obtained at much higher redshift. With the peculiar motions of their hosts, we find that the matter content at such low redshift…

Cosmology and Nongalactic Astrophysics · Physics 2013-07-25 Shuang-Nan Zhang , Yin-Zhe Ma

In contrast to the phenomenon of nullification of the cosmological constant in the equilibrium vacuum, which is the general property of any quantum vacuum, there are many options in modifying the Einstein equation to allow the cosmological…

General Relativity and Quantum Cosmology · Physics 2009-11-10 G. E. Volovik

With the basic cosmological relations that agree with the recent observations, simple expressions are suggested concerning the value of cosmological constant($\Lambda$). A large contribution of quantum vacuum to the energy momentum tensor…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Ishwaree P. Neupane

Magnetars are compact stars which are observationally determined to have very strong surface magnetic fields of the order of $10^{14}-10^{15}$G. The centre of the star can potentially have a magnetic field several orders of magnitude…

High Energy Astrophysical Phenomena · Physics 2014-05-16 Ritam Mallick , Stefan Schramm

We consider a possible connection between matter and cosmological constant $\Lambda$ via the Newtonian cosmic potential of the matter within the expanding particle horizon. Consistent with GR, an increasing potential may drive the metric…

General Physics · Physics 2014-05-30 Herman Telkamp

We report the effect of the cosmological constant and the internal energy density of a cosmic string on the deflection angle of light in the spacetime of a rotating cosmic string with internal structure. We first revisit the deflection…

General Relativity and Quantum Cosmology · Physics 2018-04-04 Kimet Jusufi , Ali Övgün

In this paper, we derive the non-commutative corrections to the maximal acceleration of a massive particle. Using the eight-dimensional kappa-deformed phase-space metric, we obtain the kappa-deformed maximal acceleration, valid up to first…

High Energy Physics - Theory · Physics 2020-12-23 E. Harikumar , Vishnu Rajagopal

The cosmological constant $\Lambda$ is a free parameter in Einstein's equations of gravity. We propose to fix its value with a boundary condition: test particles should be free when outside causal contact, e.g. at infinity. Under this…

General Physics · Physics 2019-05-24 Enrique Gaztanaga