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Aether Scalar-Tensor theory is a relativistic alternative gravity model that behaves like cold dark matter on cosmological scales while predicting the MOND force-law in astrophysical systems. The theory correctly predicts the cosmic…

General Relativity and Quantum Cosmology · Physics 2025-05-07 Christopher Reyes , Jeremy Sakstein

A stability analysis of a spherically symmetric star in scalar-tensor theories of gravity is given in terms of the frequencies of quasi-normal modes. The scalar-tensor theories have a scalar field which is related to gravitation. There is…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Tomohiro Harada

Radio polarization measurements of pulsed emission from pulsars offer a valuable insight into the basic geometry of the neutron star: inclination angle between the magnetic and rotation axis and inclination of the line of sight. So far, all…

High Energy Astrophysical Phenomena · Physics 2017-01-11 J. Pétri

We discuss boson stars and neutron stars, respectively, in a scalar-tensor gravity model with an explicitly time-dependent real scalar field. While the boson stars in our model -- in contrast to the neutron stars -- do not possess a hard…

General Relativity and Quantum Cosmology · Physics 2022-05-04 Y. Brihaye , L. Ducobu , B. Hartmann

We study the axial quasi-normal modes of neutron stars in scalar-tensor theories with massive scalar field including a self-interacting term in the potential. Various realistic equations of state including nuclear, hyperonic and hybrid…

General Relativity and Quantum Cosmology · Physics 2019-05-08 Zahra Altaha Motahar , Jose Luis Blázquez-Salcedo , Daniela D. Doneva , Jutta Kunz , Stoytcho S. Yazadjiev

We investigate neutron stars in scalar-tensor theories. We examine their secular stability against spherically symmetric perturbations by use of a turning point method. For some choices of the coupling function contained in the theories,…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Tomohiro Harada

Pulsar-timing has become a celebrated tool for probing modifications to General Relativity in the strong-field surroundings of neutron stars. Here we investigate whether scalar-tensor theories that incorporate a nonminimally coupled scalar…

General Relativity and Quantum Cosmology · Physics 2019-06-19 Raissa F. P. Mendes , Tulio Ottoni

Because of the quantum fluid properties of a neutron star core's neutrons and protons, its magnetic field is expected to be coupled strongly to its spin. This predicts a simple evolution of the surface-field of such stars as they spin down…

Astrophysics · Physics 2007-05-23 M. Ruderman

Tensor-scalar theory of gravity allows the generation of gravitational waves from astrophysical sources, like Supernov\ae{}, even in the spherical case. That motivated us to study the collapse of a degenerate stellar core, within…

Astrophysics · Physics 2009-10-31 J. Novak , J. M. Ibanez

Dwarf galaxies and globular clusters may contain intermediate mass black holes ($10^{3}$ to $10^{5}$ solar masses) in their cores. Estimates of ~$10^{3}$ neutron stars in the central parsec of the Galaxy and similar numbers in small…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Dinesh Singh , Kinwah Wu , Gordon E. Sarty

Certain scalar-tensor theories have the property of endowing stars with scalar hair, sourced either by the star's own compactness (spontaneous scalarization) or, for binary systems, by the companion's scalar hair (induced scalarization) or…

General Relativity and Quantum Cosmology · Physics 2015-01-07 Laura Sampson , Nicolas Yunes , Neil Cornish , Marcelo Ponce , Enrico Barausse , Antoine Klein , Carlos Palenzuela , Luis Lehner

The topology of the electromagnetic field around neutron stars severely impacts pulsar physics. While most of the works assume a standard centred dipolar magnetic field model, recently some efforts have been made to explain how inclusion of…

High Energy Astrophysical Phenomena · Physics 2017-07-27 Anu Kundu , Jerome Petri

We use neutron star mass and radius measurements to constrain the spontaneous scalarization phenomenon in scalar-tensor theories using Bayesian analysis. Neutron star structures in this scenario can be significantly different from the case…

General Relativity and Quantum Cosmology · Physics 2022-07-06 Semih Tuna , Kıvanç İ. Ünlütürk , Fethi M. Ramazanoğlu

Pulsars are rapidly spinning neutron stars, that radiate at the expense of their strong magnetic field and their high surface temperature. Five decades of multi-wavelength observations showed a large variety of physical parameters, such as…

High Energy Astrophysical Phenomena · Physics 2024-02-23 Michela Rigoselli

The nonminimal coupling of the kinetic term to Einstein's tensor helps the implementation of inflationary models due to the gravitationally enhanced friction. We calculate the parametrized post-Newtonian (PPN) parameters for the…

General Relativity and Quantum Cosmology · Physics 2016-07-21 Zhu Yi , Yungui Gong

Thermal and non-thermal radiation from pulsars carries significant information from surface and would have profound implications on the state of dense matter in compact stars. For the non-thermal radio emission, subpulse drifting phenomena…

High Energy Astrophysical Phenomena · Physics 2012-06-12 Shi Dai , Renxin Xu

Rotation distorts the vacuum magnetic field of a pulsar from that of a simple dipole. The effect is particularly strong close to the light cylinder, but also affects the field close to the stellar surface. We find the shape and locus of the…

Astrophysics · Physics 2012-08-27 P. N. Arendt, , J. A. Eilek

Pulsars are unique astrophysical laboratories because of their clock-like timing precision, providing new ways to test general relativity and detect gravitational waves. One impediment to high-precision pulsar timing experiments is timing…

Solar and Stellar Astrophysics · Physics 2015-05-20 Rachel Rosen , Maura A. McLaughlin , Susan E. Thompson

Pulsars are stars that emit electromagnetic radiation in well-defined time intervals. The frequency of such pulses decays with time as is quantified by the {\it braking index} ($n$). In the canonical model $n = 3$ for all pulsars, but…

High Energy Astrophysical Phenomena · Physics 2018-11-28 H. O. Oliveira , N. S. Magalhaes , R. M. Marinho , G. A. Carvalho , C. Frajuca

Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields…

High Energy Astrophysical Phenomena · Physics 2016-12-21 Samuel E. Gralla , Alexandru Lupsasca , Alexander Philippov
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