Neutron stars origins and masses

Horvath, J. E.; Rocha, L. S.; Bernardo, A.; Valientim, Rodolfo; Avellar, Marcio G. B. de

doi:10.1002/asna.202113922

Cited by 8 publications

(7 citation statements)

References 33 publications

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“…These observations have challenged our view about the mass of neutron stars, which peaks at about the Chandrasekhar limit of

1.4\hspace*{3.33333pt}{M}_{\odot}

. [ 91 ] A recent determination of the mass of the pulsar PSR J0952‐0607, the fastest known rotating neutron star in the disk of the Milky Way, yielded a maximum mass of the order of

2.52\hspace*{3.33333pt}{M}_{\odot}

=(2.35\pm 0.17)\hspace*{3.33333pt}{M}_{\odot}

]. The mass of PSR J0952‐0607 challenges our understanding of the equation of state for the dense matter.…”

Section: Discussionmentioning

confidence: 99%

Existence of Dark Energy Stars within Lower Mass Gap in the Realm of f(Q)$f(Q)$ Gravity

Bhar

2023

Fortschritte der Physik

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The object of this article is to study a new class of dark energy stars in the background of gravity by using the metric potentials proposed by Krori‐Barua [J. Phys. A, Math. Gen. 8:508 (1975)]. To achieve the goal, a quadratic form of as is taken into account for the static spherically symmetric spacetime,`a' being a coupling parameter of gravity. The maximum allowable masses with corresponding radii have been obtained via plots for and 8. The obtained maximum masses from our analysis are found in the range . For a smaller value of the coupling parameter ‘a’ associated with gravity, more massive stars are found. The radii corresponding to the maximum masses also increase with decreasing ‘a’. In particular, when , the theory can achieve a dark energy star of mass for certain specific combinations of model parameters. This obtained mass is located within a mass in the range of and that can be a lighter object in the GW190814 event detected by LIGO/VIRGO experiments.

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“…These observations have challenged our view about the mass of neutron stars, which peaks at about the Chandrasekhar limit of

1.4\hspace*{3.33333pt}{M}_{\odot}

. [ 91 ] A recent determination of the mass of the pulsar PSR J0952‐0607, the fastest known rotating neutron star in the disk of the Milky Way, yielded a maximum mass of the order of

2.52\hspace*{3.33333pt}{M}_{\odot}

=(2.35\pm 0.17)\hspace*{3.33333pt}{M}_{\odot}

]. The mass of PSR J0952‐0607 challenges our understanding of the equation of state for the dense matter.…”

Section: Discussionmentioning

confidence: 99%

Existence of Dark Energy Stars within Lower Mass Gap in the Realm of f(Q)$f(Q)$ Gravity

Bhar

2023

Fortschritte der Physik

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“…A large number of accurate observations on the masses and radii obtained from massive pulsars, the gravitational wave event GW170817, or PSR J0030+0451 massradius relation from Neutron Star Interior Composition Explorer (NICER) data have dramatically changed our understanding of the mass distribution of neutron stars, by challenging the paradigm according to which the mass of the neutron stars peaks at around the Chandrasekhar limit of 1.4M ⊙ [99]. For example, the mass of the pulsar PSR J0952-0607, the fastest known rotating neutron star in the disk of the Milky Way, has been determined recently, giving a maximal mass of the order of 2.52M ⊙ (M = 2.35 ± 0.17M ⊙ ).…”

Section: Discussion and Final Remarksmentioning

confidence: 99%

“…However, the standard view on the neutron star masses has changed drastically recently, once more and more exact determinations of the neutron star masses became available [14]. A large number of accurate astronomical observations, as well as the detection of the gravitational waves, has clearly indicated that the masses of neutron stars vary in a much larger range than expected from the simple application of the Chandrasekhar limit.…”

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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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“…Still, in this bound the effects of the rotation and of the existence of ex-otic states of matter are ignored. On the other hand, a number of theoretical arguments, that seemed to be supported by the observational evidence, suggested that neutron stars had a characteristic, unique mass of the order of 1.4M ⊙ [2]. Assuming an interaction among neutrons, the role of the repulsive interactions should be important, thus leading to a numerical coincidence with the Chandrasekhar mass [3].…”

mentioning

confidence: 98%

“…Assuming an interaction among neutrons, the role of the repulsive interactions should be important, thus leading to a numerical coincidence with the Chandrasekhar mass [3]. This coincidence led to postulate that some specific physical processes at the birth of neutron star would uniquely fix its mass [2]. However, with the increase in the precision of the astronomical observations, the paradigm of a unique mass distribution around 1.4M ⊙ of the neutron stars has to abandoned, and the existence of neutron stars with light (1.174 ± 0.004M ⊙ ) [4], or heavy (2.140.010.09M ⊙ ) [5] masses is presently well established.…”

mentioning

confidence: 99%

Compact stars in the Einstein dark energy model

Haghani,

Harko

2022

Preprint

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We investigate the properties of high density compact objects in a vector type theory, inspired by Einstein's 1919 theory of elementary particles, in which Einstein assumed that elementary particles are held together by gravitational as well as electromagnetic type forces. From a modern perspective, Einstein's theory can be interpreted as a vector type model, with the gravitational action constructed as a linear combination of the Ricci scalar, of the trace of the matter energy-momentum tensor, and of a massive self-interacting vector type field. To obtain the properties of stellar models we consider the field equations for a static, spherically symmetric system, and we investigate numerically their solutions for different equations of state of quark and neutron matter, by assuming that the selfinteraction potential of the vector field either vanishes, or is quadratic in the vector field potential. We consider quark stars described by the MIT bag model equation of state, and in the Color Flavor Locked (CFL) phase, as well as compact stars consisting of a Bose-Einstein Condensate of neutron matter, with neutrons forming Cooper pairs. Constant density stars, representing a generalization of the Interior Schwarzschild solution of general relativity, are also analyzed. As an example of stars described by equations of state obtained by using effective nuclear interactions of the Skyrme type we consider the Douchin-Haensel (SLy) equation of state. The numerical solutions are explicitly obtained in both standard general relativity, and the Einstein dark energy model, and an in depth comparison between the astrophysical predictions of these two theories are performed. As a general conclusion of our study we find that for all the considered equations of state a much larger variety of stellar structures can be obtained in the Einstein dark energy model, including classes of stars that are more massive than their general relativistic counterparts. As a concrete applications of our results we suggest that compact objects with masses of the order of 2.5M⊙, associated, for example, with the GW 190814 gravitational wave event, could be in fact quark or neutron stars, described by the Einstein dark energy model.

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Neutron stars origins and masses

Cited by 8 publications

References 33 publications

Existence of Dark Energy Stars within Lower Mass Gap in the Realm of f(Q)$f(Q)$ Gravity

Existence of Dark Energy Stars within Lower Mass Gap in the Realm of f(Q)$f(Q)$ Gravity

Compact stellar structures in Weyl geometric gravity

Compact stars in the Einstein dark energy model

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