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A secular variation of $G$ modifies the structure and evolutionary time scales of white dwarfs. Using an state-of-the-art stellar evolutionary code, an up-to-date pulsational code, and a detailed population synthesis code we demonstrate…

White dwarf atmospheres are subjected to gravitational potentials around $10^5$ times larger than occur on Earth. They provide a unique environment in which to search for any possible variation in fundamental physics in the presence of…

Using a perturbative approach we solve stellar structure equations for low-density (solar-type) stars whose interior is described with a polytropic equation of state in scenarios involving a subset of modified gravity theories. Rather than…

Solar and Stellar Astrophysics · Physics 2019-02-27 M. Cermeño , J. Carro , A. L. Maroto , M. Ángeles Pérez-García

Considering extreme-mass-ratio inspirals along with the conservative dynamics of gravitational self-force, we compare viable theories of gravity. In particular, by examining a Schwarzschild background we analyse the self-force-induced…

General Relativity and Quantum Cosmology · Physics 2021-11-08 Vincenzo Ventriglia

Testing gravity by binary pulsars nowadays becomes a key issue. Screened modified gravity is a kind of scalar-tensor theory with screening mechanism in order to satisfy the tight Solar System tests. In this paper, we investigate how the…

General Relativity and Quantum Cosmology · Physics 2020-03-04 Xing Zhang , Wen Zhao , Tan Liu , Kai Lin , Chao Zhang , Xiang Zhao , Shaojun Zhang , Tao Zhu , Anzhong Wang

Modified gravity theories on cosmic scales have three key deviations from general relativity. They can cause cosmic acceleration without a physical, highly negative pressure fluid, can cause a gravitational slip between the two metric…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-04 Eric V. Linder

Noncommutative geometry is one of the quantum gravity theories, which various researchers have been using to describe different physical and astrophysical systems. However, so far, no direct observations can justify its existence, and this…

General Relativity and Quantum Cosmology · Physics 2023-01-27 Surajit Kalita , T. R. Govindarajan , Banibrata Mukhopadhyay

The observation of low-frequency gravitational waves with the Laser Interferometer Space Antenna will allow the study of new sources of gravitational radiation that are not accessible by ground-based instruments. Gravitational wave sources…

General Relativity and Quantum Cosmology · Physics 2019-05-22 Tyson B. Littenberg , Nicolas Yunes

We consider a relativistic, degenerate, electron gas under the influence of a strong magnetic field, which describes magnetized white dwarfs. Landau quantization changes the density of states available to the electrons, thus modifying the…

High Energy Astrophysical Phenomena · Physics 2012-11-20 Upasana Das , Banibrata Mukhopadhyay

Within the framework of $f(R)=R+\alpha R^2$ gravity, we study realistic models of neutron stars, using equations of state compatible with the LIGO constraints. i.e. APR4, MPA1, SLy, and WW1. By numerically solving modified…

High Energy Astrophysical Phenomena · Physics 2020-02-26 Pasquale Feola , Xisco Jimenez Forteza , Salvatore Capozziello , Roberto Cianci , Stefano Vignolo

We report strong cosmological constraints on the Brans-Dicke (BD) theory of gravity using Cosmic Microwave Background data from Planck.We consider two types of models. First, the initial condition of the scalar field is fixed to give the…

Cosmology and Nongalactic Astrophysics · Physics 2014-07-09 A. Avilez , C. Skordis

The prediction of the spins of the compact remnants is a fundamental goal of the theory of stellar evolution. Here, we confront the predictions for white dwarf spins from evolutionary models including rotation with observational…

Astrophysics · Physics 2009-11-13 M. P. L. Suijs , N. Langer , A. -J. Poelarends , S. -C. Yoon , A. Heger , F. Herwig

Under the assumption of a specific nonminimal coupling of torsion to Under the assumption of a specific nonminimal coupling of torsion to electromagnetism, spacetime is birefringent in the presence of a gravitational field leading to…

Astrophysics · Physics 2007-05-23 Oliver Preuss , Stefan Jordan , Mark P. Haugan , Sami K. Solanki

We determine the conditions for which the constraints from lunar laser ranging on the time evolution of the local gravitational constant can be extrapolated to impose constraints on the time evolution of the cosmological gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-13 Clare Burrage , Johannes Dombrowski

The missing gravity in galaxies requires dark matter, or alternatively a modification of gravity or inertia. These theoretical possibilities of fundamental importance may be distinguished by the statistical relation between the observed…

Astrophysics of Galaxies · Physics 2022-12-21 Kyu-Hyun Chae

In this paper we derive a bound on the rate of change of the gravitational constant G coming from the pulsating white dwarf G117-B15A. This star is a ZZ Ceti pulsator extensively studied with astroseismological techniques for last three…

Astrophysics · Physics 2009-11-07 Marek Biesiada , Beata Malec

The almost simultaneous detection of gravitational waves and a short gamma-ray burst from a neutron star merger has put a tight constraint on the difference between the speed of gravity and light. In the four-dimensional scalar-tensor…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-17 Marco Crisostomi , Kazuya Koyama

Massive, highly magnetized white dwarfs with fields up to $10^9$ G have been observed and theoretically used for the description of a variety of astrophysical phenomena. Ultramagnetized white dwarfs with uniform interior fields up to…

Solar and Stellar Astrophysics · Physics 2014-09-29 J. G. Coelho , R. M. Marinho , M. Malheiro , R. Negreiros , D. L. Cáceres , J. A. Rueda , R. Ruffini

It has been suggested that Einstein's theory of General Relativity can be modified to accomodate mismatches between the gravitational field and luminous matter on a wide range of scales. Covariant theories of modified gravity generically…

Astrophysics · Physics 2009-03-31 P. G Ferreira , C. Skordis , C. Zunckel

In a modified gravity theory, the propagation equation of gravitational waves will be presented in a non-standard way. Therefore this tenor mode perturbation of time-space, as a complement to the scalar mode perturbation, provides a unique…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Lixin Xu