Equation of states in the curved spacetime of slowly rotating degenerate stars

Hossain, Golam Mortuza; Mandal, Susobhan

doi:10.1088/1475-7516/2022/10/008

Cited by 3 publications

(2 citation statements)

References 38 publications

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“…For example, in the σ − ω model of nuclear matter, the maximum mass increases from 1.61M ⊙ to 2.24M ⊙ , respectively. The effects of the time dilation on the equation of state inside slowly rotating neutron stars was investigated in [111], where it was shown that the equation of state also depends on the frame dragging effect. However, while the time dilation effect leads to a significant increase of the mass of the star, the frame dragging has a negligible influence on the maximum mass of the star.…”

Section: Discussion and Final Remarksmentioning

confidence: 99%

Compact stellar structures in Weyl geometric gravity

Haghani¹,

Harkó²

2023

Preprint

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We consider the structure and physical properties of specific classes of neutron, quark, and Bose-Einstein Condensate stars in the conformally invariant Weyl geometric gravity theory. The basic theory is derived from the simplest conformally invariant action, constructed, in Weyl geometry, from the square of the Weyl scalar, the strength of the Weyl vector, and a matter term, respectively. The action is linearized in the Weyl scalar by introducing an auxiliary scalar field. To keep the theory conformally invariant the trace condition is imposed on the matter energy-momentum tensor. The field equations are derived by varying the action with respect to the metric tensor, Weyl vector field and scalar field. By adopting a static spherically symmetric interior geometry, we obtain the field equations, describing the structure and properties of stellar objects in Weyl geometric gravity. The solutions of the field equations are obtained numerically, for different equations of state of the neutron and quark matter. More specifically, constant density stellar models, and models described by the stiff fluid, radiation fluid, quark bag model, and Bose-Einstein Condensate equations of state are explicitly constructed numerically in both general relativity and Weyl geometric gravity, thus allowing an in depth comparison between the predictions of these two gravitational theories. As a general result it turns out that for all the considered equations of state, Weyl geometric gravity stars are more massive than their general relativistic counterparts. As a possible astrophysical application of the obtained results we suggest that the recently observed neutron stars, with masses in the range of 2M⊙ and 3M⊙, respectively, could be in fact conformally invariant Weyl geometric neutron or quark stars.

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Section: Discussion and Final Remarksmentioning

confidence: 99%

Compact stellar structures in Weyl geometric gravity

Haghani¹,

Harkó²

2023

Preprint

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“…The regularity of the equation (7.2) additionally demands ω ′ (0) = 0. By using the curved spacetime of a slowly rotating star, the equation of state for an ensemble of degenerate neutrons has been computed in an accompanying article [21]. Additionally, a numerical method for solving corresponding Einstein's equation together with the constraints is also described there.…”

Section: Slowly Rotating Neutron Starmentioning

confidence: 99%

Origin of primeval seed magnetism in rotating astrophysical bodies

Hossain,

Mandal

2024

J. Cosmol. Astropart. Phys.

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We show that a primeval seed magnetic field arises due to spin-degeneracy breaking of fermions caused by the dragging of inertial frames in the curved spacetime of rotating astrophysical bodies. This seed magnetic field would arise even due to electrically neutral fermions such as neutrons. As examples, firstly we show that an ideal neutron star rotating at 500 revolutions per second, having mass 0.83 M⊙ and described by an ensemble of degenerate neutrons, would have 0.12 Gauss seed magnetic field at its center arising through the breaking of spin-degeneracy. Secondly, similar seed field at a proto-galactic stage for the Milky Way galaxy as implied by its observed rotation curve is estimated to be between 10-19–10-24 Gauss, a field strength which is known to be sufficient to produce presently observed microgauss magnetic field.

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Compact stellar structures in Weyl geometric gravity

Haghani

Harkó

2023

Phys. Rev. D

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Equation of states in the curved spacetime of slowly rotating degenerate stars

Cited by 3 publications

References 38 publications

Compact stellar structures in Weyl geometric gravity

Compact stellar structures in Weyl geometric gravity

Origin of primeval seed magnetism in rotating astrophysical bodies

Compact stellar structures in Weyl geometric gravity

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