On Massive Neutron Cores

Oppenheimer, J. Robert; Volkoff, G. M.

doi:10.1103/physrev.55.374

Cited by 3,565 publications

(2,793 citation statements)

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“…As extensively studied, once GR is assumed as the correct theory of gravity, there are certainly upper limits for realistic neutron star masses, being the theoretical mass limit itself increased along the years, from O(0.6M ⊙ ) that Tolman-Oppenheimer-Volkoff (TOV) [12] found for a free neutron gas equation of state (EoS), to O(2.2M ⊙ ) limits when stiffer chiral interactions are allowed [13]. Notwithstanding, the discovery of a neutron star with mass 1.974M ⊙ [14] by the Shapiro delay method, confirmed some years after by a precise sighting [15] through binary system measurements, have indeed put into question the validity of GR in such high-energy gravitational environment and have been able to rule out exotic EoS proposals.…”

Section: And References Therein)mentioning

confidence: 99%

The realistic models of relativistic stars in f ( R ) = R + αR ² gravity

Astashenok

Odintsov

Cruz-Dombriz

2017

Class. Quantum Grav.

158

104

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The realistic models of relativistic stars in f (R) = R + αR 2 gravity In the context of f (R) = R + αR 2 gravity, we study the existence of neutron and quark stars for various α with no intermediate approximation in the system of equations. Analysis shows that for positive α the scalar curvature does not drop to zero at the star surface (as in General Relativity) but exponentially decreases with distance. Also the stellar mass bounded by star surface decreases when the value α increases. Nonetheless distant observers would observe a gravitational mass due to appearance of a so-called gravitational sphere around the star. The non-zero curvature contribution to the gravitational mass eventually is shown to compensate the stellar mass decrease for growing α's. We perform our analysis for several equations of state including purely hadronic configurations as well as hyperons and quark stars. In all cases, we assess that the relation between the parameter α and the gravitational mass weakly depends upon the chosen equation of state. Another interesting feature is the increase of the star radius in comparison with General Relativity for stars with masses close to maximal, whereas for intermediate masses 1.4 − 1.6M⊙ the radius of star depends upon α very weakly. Also the decrease in the mass bounded by star surface may cause the surface redshift to decrease in R 2 -gravity when compared to Einsteinian predictions. This effect is shown to hardly depend upon the observed gravitational mass. Finally, for negative values of α our analysis shows that outside the star the scalar curvature has damped oscillations but the contribution of the gravitational sphere into the gravitational mass increases indefinitely with radial distance putting into question the very existence of such relativistic stars.

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Section: And References Therein)mentioning

confidence: 99%

The realistic models of relativistic stars in f ( R ) = R + αR ² gravity

Astashenok

Odintsov

Cruz-Dombriz

2017

Class. Quantum Grav.

158

104

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“…This configuration is called a neutron star. Oppenheimer and Volkoff [72] studied relativistic models of neutron stars, assuming an ideal gas of free neutrons. The discovery of pulsars [43], astronomical objects which emit periodic signals, led some authors [31] to propose that these objects correspond to rotating neutron stars.…”

Section: Gravitational Collapsementioning

confidence: 99%

Slowly rotating supercompact Schwarzschild stars

Posada¹

2017

Monthly Notices of the Royal Astronomical Society

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AcknowledgmentsI am grateful to the universe, for its harmony. The project is the study of integral and surface properties of slowly rotating homogeneous masses in the gravastar limit R → R s , where R s is the Schwarzschild radius. For this purpose we followed the perturbative method proposed by Hartle in 1967. In this model, the relativistic equations of structure for a slowly rotating star were derived at second order in the angular velocity Ω. An interesting, and educational, application of this model was investigated by Chandrasekhar and Miller. I am indebted to the Department of Physics andIn their approach, they solved numerically the structure equations of a homogeneous star (constant energy density) up to the Buchdahl bound (9/8)R s . Based on this work, our objective was to investigate the interesting region below the Buchdahl bound R s < R < (9/8)R s , which has not been studied previously in the literature.Our results were astonishing. We found that the surface properties and quadrupole mass moment approach the values corresponding to those of the Kerr metric when expanded at second order in angular momentum. This remarkable result provides a long sought solution to the problem of the source of rotation in the Kerr spacetime.iv

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“…As such a supermassive degenerate neutrino ball has a radius of only 4.45 Schwarzschild radii [19], it is almost a black hole. Thus the maximal mass scale of these objects may be linked to the existence of a sterile neutrino of ∼ 15 keV/c 2 mass, in a similar fashion as the maximal mass scale of the neutron stars is linked to the effective mass of the neutron [20].…”

Section: A Symbiotic Black Hole Formation Scenariomentioning

confidence: 99%

“…The maximal mass that a self-gravitating degenerate neutrino ball can support gravitationally, is the Oppenheimer-Volkoff (OV) limit [19] M max = 0.5430…”

Section: A Symbiotic Black Hole Formation Scenariomentioning

confidence: 99%

“…As in contrast to pulsars, black holes do presumably not acquire "black hole kicks" during a supernova explosion, the velocity of the stellar-mass black hole will be small compared to the escape velocity from the center of the neutrino ball. For a ball of 3×10 6 M ⊙ mass and 25 light-days radius [17], consisting of degenerate sterile neutrinos of 15 keV/c 2 mass and degeneracy factor g = 2, the escape velocity from the center is 1700 km/s, while for a ball of the same sterile neutrinos at the OV-limit, with 2.8×10 9 M ⊙ mass and 1.4 light-days radius, the escape velocity from the center is the velocity of light [19].…”

Section: A Symbiotic Black Hole Formation Scenariomentioning

confidence: 99%

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A symbiotic scenario for the rapid formation of supermassive black holes

Richter

Tupper

Viollier³

2006

J. Cosmol. Astropart. Phys.

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Abstract. The most massive black holes, lurking at the centers of large galaxies, must have formed less than a billion years after the big bang, as they are visible today in the form of bright quasars at redshift larger than six. Their early appearance is mysterious, because the radiation pressure, generated by infalling ionized matter, inhibits the rapid growth of these black holes from stellar-mass black holes. It is shown that the supermassive black holes may form timeously through the accretion of predominantly degenerate sterile neutrino dark matter onto stellar-mass black holes. Our symbiotic scenario relies on the formation of, first, supermassive degenerate sterile neutrino balls through gravitational cooling and, then, stellar-mass black holes through supernova explosions of massive stars at the center of the neutrino balls. The observed lower and upper limits of the supermassive black holes are explained by the corresponding mass limits of the preformed neutrino balls.

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On Massive Neutron Cores

Cited by 3,565 publications

References 4 publications

The realistic models of relativistic stars in f ( R ) = R + αR ² gravity

The realistic models of relativistic stars in f ( R ) = R + αR ² gravity

Slowly rotating supercompact Schwarzschild stars

A symbiotic scenario for the rapid formation of supermassive black holes

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On Massive Neutron Cores

Cited by 3,565 publications

References 4 publications

The realistic models of relativistic stars in f ( R ) = R + αR 2 gravity

The realistic models of relativistic stars in f ( R ) = R + αR 2 gravity

Slowly rotating supercompact Schwarzschild stars

A symbiotic scenario for the rapid formation of supermassive black holes

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The realistic models of relativistic stars in f ( R ) = R + αR ² gravity

The realistic models of relativistic stars in f ( R ) = R + αR ² gravity