Log in

Relevant bibliographies by topics / Neutron stars masses / Journal articles

Journal articles on the topic 'Neutron stars masses'

To see the other types of publications on this topic, follow the link: Neutron stars masses.

Author: Grafiati

Published: 9 March 2023

Last updated: 10 March 2023

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Neutron stars masses.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Horvath, Jorge Ernesto, Lívia S. Rocha, Antonio Bernardo, Rodolfo Valientim, and Marcio Guilherme Bronzato Avellar. "Neutron stars origins and masses." Astronomische Nachrichten 342, no. 1-2 (January 2021): 294–99. http://dx.doi.org/10.1002/asna.202113922.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Kreim, S., M. Hempel, D. Lunney, and J. Schaffner-Bielich. "Nuclear masses and neutron stars." International Journal of Mass Spectrometry 349-350 (September 2013): 63–68. http://dx.doi.org/10.1016/j.ijms.2013.02.015.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Beck, D. H. "Neutron decay, dark matter and neutron stars." EPJ Web of Conferences 219 (2019): 05006. http://dx.doi.org/10.1051/epjconf/201921905006.

Full text

Abstract:

Following up on a suggestion that decay to a dark matter fermion might explain the 4σ discrepancy in the neutron lifetime, we consider the implications of such a fermion on neutron star structure. We find that including it reduces the maximum neutron star mass to well below the observed masses. In order to recover stars with the observed masses, the (repulsive) self-interactions of the dark fermion would have to be stronger than those of the nucleon-nucleon interaction.

APA, Harvard, Vancouver, ISO, and other styles

4

de Souza, Gibran H., Ernesto Kemp, and Cecilia Chirenti. "Magnetized Neutron Stars." International Journal of Modern Physics: Conference Series 45 (January 2017): 1760032. http://dx.doi.org/10.1142/s2010194517600321.

Full text

Abstract:

In this work we show the results for numerical solutions of the relativistic Grad-Shafranov equation for a typical neutron star with 1.4 solar masses. We have studied the internal magnetic field considering both the poloidal and toroidal components, as well as the behavior of the field lines parametrized by the ratio between these components of the field.

APA, Harvard, Vancouver, ISO, and other styles

5

MENEZES, DÉBORA P., and C. PROVIDÊNCIA. "FINITE TEMPERATURE EQUATIONS OF STATE FOR MIXED STARS." International Journal of Modern Physics D 13, no. 07 (August 2004): 1249–53. http://dx.doi.org/10.1142/s0218271804005389.

Full text

Abstract:

We investigate the properties of mixed stars formed by hadronic and quark matter in β-equilibrium described by appropriate equations of state (EOS) in the framework of relativistic mean-field theory. The calculations were performed for T=0 and for finite temperatures and also for fixed entropies with and without neutrino trapping in order to describe neutron and proto-neutron stars. The star properties are discussed. Maximum allowed masses for proto-neutron stars are much larger when neutrino trapping is imposed.

APA, Harvard, Vancouver, ISO, and other styles

6

JAIKUMAR, P., C. GALE, D. PAGE, and M. PRAKASH. "DISTINGUISHING BARE QUARK STARS FROM NEUTRON STARS." International Journal of Modern Physics A 19, no. 31 (December 20, 2004): 5335–42. http://dx.doi.org/10.1142/s0217751x04022566.

Full text

Abstract:

Observations to date cannot distinguish neutron stars from self-bound bare quark stars on the basis of their gross physical properties such as their masses and radii alone. However, their surface luminosity and spectral characteristics can be significantly different. Unlike a normal neutron star, a bare quark star can emit photons from its surface at super-Eddington luminosities for an extended period of time. We present a calculation of the photon bremsstrahlung rate from the bare quark star's surface, and indicate improvements that are required for a complete characterization of the spectrum. The observation of this distinctive photon spectrum would constitute an unmistakable signature of a strange quark star and shed light on color superconductivity at stellar densities.

APA, Harvard, Vancouver, ISO, and other styles

7

Husain, Wasif, Theo F. Motta, and Anthony W. Thomas. "Consequences of neutron decay inside neutron stars." Journal of Cosmology and Astroparticle Physics 2022, no. 10 (October 1, 2022): 028. http://dx.doi.org/10.1088/1475-7516/2022/10/028.

Full text

Abstract:

Abstract The hypothesis that neutrons might decay into dark matter is explored using neutron stars as a testing ground. It is found that in order to obtain stars with masses at the upper end of those observed, the dark matter must experience a relatively strong self-interaction. Conservation of baryon number and energy then require that the star must undergo some heating, with a decrease in radius, leading to an increase in speed of rotation over a period of days.

APA, Harvard, Vancouver, ISO, and other styles

8

Astashenok, A. V., S. Capozziello, S. D. Odintsov, and V. K. Oikonomou. "Maximum baryon masses for static neutron stars in f(R) gravity." Europhysics Letters 136, no. 5 (December 1, 2021): 59001. http://dx.doi.org/10.1209/0295-5075/ac3d6c.

Full text

Abstract:

Abstract We investigate the upper mass limit predictions of the baryonic mass for static neutron stars in the context of f(R) gravity. We use the most popular f(R) gravity model, namely the R 2 gravity, and calculate the maximum baryon mass of static neutron stars adopting several realistic equations of state and one ideal equation of state, namely that of causal limit. Our motivation is based on the fact that neutron stars with baryon masses larger than the maximum mass for static neutron star configurations inevitably collapse to black holes. Thus with our analysis, we want further to enlighten the predictions for the maximum baryon masses of static neutron stars in R 2 gravity, which, in turn, further strengthens our understanding of the mysterious mass gap region. As we show, the baryon masses of most of the equations of states studied in this paper lie in the lower limits of the mass gap region – , but intriguingly enough, the highest value of the maximum baryon masses we found is of the order of . This upper mass limit also appears as a maximum static neutron star gravitational mass limit in other contexts. Combining the two results which refer to baryon and gravitational masses, we point out that the gravitational mass of static neutron stars cannot be larger than three solar masses, while based on maximum baryon masses results of the present work, we can conspicuously state that it is highly likely the lower mass limits of astrophysical black holes in the range of – . This, in turn, implies that maximum neutron star masses in the context of R 2 gravity are likely to be in the lower limits of the range of – . Hence our work further supports the General Relativity claim that neutron stars cannot have gravitational masses larger than and then, to explain observations comparable or over this limit, we need alternative extensions of General Relativity, other than f(R) gravity.

APA, Harvard, Vancouver, ISO, and other styles

9

Heiselberg, Henning, and Vijay Pandharipande. "Recent Progress in Neutron Star Theory." Annual Review of Nuclear and Particle Science 50, no. 1 (December 2000): 481–524. http://dx.doi.org/10.1146/annurev.nucl.50.1.481.

Full text

Abstract:

▪ Abstract We review recent progress in the theory of neutron stars and compare its predictions with the observational data on masses, radii, and temperatures. The theory of neutron stars made up of neutrons, protons, and leptons is discussed in detail along with recent models of nuclear forces and modern many-body techniques. The possibilities of pion and kaon condensation in dense neutron star matter are considered, as is the possible occurrence of strange hyperons and quark-matter drops in the stellar core. The structure of mixed-phase matter in neutron stars, as well as the probable effect of phase transitions on the spin down of pulsars, is also discussed.

APA, Harvard, Vancouver, ISO, and other styles

10

Gondek, Dorota. "Neutron stars and strange stars." International Astronomical Union Colloquium 160 (1996): 133–34. http://dx.doi.org/10.1017/s0252921100041282.

Full text

Abstract:

If strange quark plasma is the real ground state of baryonic matter (Witten 1984), then some of neutron stars (NS) could actually be strange stars (SS). It is difficult to distinguish SS from NS observationally. They have similar radii and masses and their crusts are built of the same matter. It seems that a good method for testing the existence of SS would be the studies of phenomena related to the stellar pulsations. In 1976 Boriakoff proposed that radial oscillations of NS could be observed within radio subpulses of pulsars. While various modes of pulsations of NS were studied by a number of authors, little attention was paid to seismological signatures of SS. The radial oscilations of bare SS were studied by Väth & Chanmugam (1992). Recently Weber (this volume) studied properties of stars made of matter described by BPS equation of state (EOS) (Baym et al. 1971) with a ball of strange matter inside, but they mainly concentrated on stability of white-dwarf-like SS. In this work I present fully relativistic calculations of the radial oscillation frequencies of SS. I determined the fundamental frequency for bare SS and SS with two different types of crusts depending on origin (Alcock et al. 1986) of SS and showed differences between them.

APA, Harvard, Vancouver, ISO, and other styles

11

Xu, Yan, Wen Bo Ding, Cheng Zhi Liu, and J. L. Han. "Nucleonic Direct Urca Processes and Cooling of the Massive Neutron Star by Antikaon Condensations." Advances in Astronomy 2020 (October 16, 2020): 1–7. http://dx.doi.org/10.1155/2020/6146913.

Full text

Abstract:

Nucleonic direct Urca processes and cooling of the massive neutron stars are studied by considering antikaon condensations. Calculations are performed in the relativistic mean field and isothermal interior approximations. Neutrino energy losses of the nucleonic direct Urca processes are reduced when the optical potential of antikaons changes from − 80 to − 130 MeV. If the center density of the massive neutron stars is a constant, the masses taper off with the optical potential of antikaons, and neutrino luminosities of the nucleonic direct Urca processes decrease for ρ CN = 0.5 fm − 3 but first increase and then decrease for larger ρ CN . Large optical potential of antikaons results in warming of the nonsuperfluid massive neutron stars. Massive neutron stars turn warmer with the protonic S 0 1 superfluids. However, the decline of the critical temperatures of the protonic S 0 1 superfluids for the large optical potential of antikaons can speed up the cooling of the massive neutron stars.

APA, Harvard, Vancouver, ISO, and other styles

12

Montoli, A., M. Antonelli, and P. M. Pizzochero. "The role of mass, equation of state, and superfluid reservoir in large pulsar glitches." Monthly Notices of the Royal Astronomical Society 492, no. 4 (January 20, 2020): 4837–46. http://dx.doi.org/10.1093/mnras/staa149.

Full text

Abstract:

ABSTRACT Observations of pulsar glitches may provide insights on the internal physics of neutron stars and recent studies show how it is in principle possible to constrain pulsar masses with timing observations. The reliability of these estimates depends on the current uncertainties about the structure of neutron stars and on our ability to model the dynamics of the superfluid neutrons in the internal layers. We assume a simplified model for the rotational dynamics of a neutron star and estimate an upper bound to the mass of 25 pulsars from their largest glitch and average activity: the aim is to understand to which extent the mass constraints are sensitive to the choice of the unknown structural properties of neutron stars, like the extension of the superfluid region and the equation of state. Reasonable values, within the range measured for neutron star masses, are obtained only if the superfluid domain extends for at least a small region inside the outer core, which is compatible with calculations of the neutron S-wave pairing gap. Moreover, the mass constraints stabilize when the superfluid domain extends to densities over nuclear saturation, irrespective of the equation of state tested.

APA, Harvard, Vancouver, ISO, and other styles

13

Motta, T. F., P. A. M. Guichon, and A. W. Thomas. "Neutron to dark matter decay in neutron stars." International Journal of Modern Physics A 33, no. 31 (November 10, 2018): 1844020. http://dx.doi.org/10.1142/s0217751x18440207.

Full text

Abstract:

Recent proposals have suggested that a previously unknown decay mode of the neutron into a dark matter particle could solve the long lasting measurement problem of the neutron decay width. We show that, if the dark particle in neutron decay is the major component of the dark matter in the universe, this proposal is in disagreement with modern astrophysical data concerning neutron star masses.

APA, Harvard, Vancouver, ISO, and other styles

14

Noda, Tsuneo, Nobutoshi Yasutake, Masa-aki Hashimoto, Toshiki Maruyama, and Toshitaka Tatsumi. "Cooling of neutron stars with quark-hadron continuity." EPJ Web of Conferences 260 (2022): 11024. http://dx.doi.org/10.1051/epjconf/202226011024.

Full text

Abstract:

Neutron stars are high-density objects formed by the gravitational collapse of massive stars, and the whole star can be likened to a giant nucleus. The interior of a neutron star is considered to contain exotic particles and states which do not appear in a normal nucleus. The internal states are constrained by observations of masses and radii via the equation of state of highly dense nuclear matter. Within these constraints, a variety of exotic states have been discussed. The internal state of neutron stars is closely related to its neutrino emission process, which cools the star from the inside. This effect can be compared with observations of the surface temperature of neutron stars. However, despite the wide range of observations of neutron stars, the nature of the neutron star matter remains uncertain. We consider quark matter as an exotic state and perform cooling calculations for neutron stars, incorporating the effects of nucleon superﬂuidity and quark colour superconductivity.We take into account the “quark-hadron continuity”, in which the neutron superﬂuidity is succeeded by thedquark pairing. Furthermore, we obtained the range of the neutron star cooling curve, taking into account the difference in surface temperature due to the composition of the surface layer. We found that the existence of quark matter causes strong neutrino emission from quarks, which is moderately suppressedbysuperﬂuidity and superconductivity, and canexplain the cold surface temperature of neutron stars.

APA, Harvard, Vancouver, ISO, and other styles

15

HEISELBERG, HENNING. "NEUTRON STARS: RECENT DEVELOPMENTS." International Journal of Modern Physics B 15, no. 10n11 (May 10, 2001): 1519–34. http://dx.doi.org/10.1142/s0217979201006008.

Full text

Abstract:

Recent developments in neutron star theory and observation are discussed. Based on modern nucleon-nucleon potentials more reliable equations of state for dense nuclear matter have been constructed. Furthermore, phase transitions such as pion, kaon and hyperon condensation, superfluidity and quark matter can occur in cores of neutron stars. Specifically, the nuclear to quark matter phase transition and its mixed phases with intriguing structures are treated. Rotating neutron stars with and without phase transitions are discussed and compared to observed masses, radii and glitches. The observations of possible heavy ~2M⊙ neutron stars in X-ray binaries and quasi-periodic oscillations require relatively stiff equations of state and restrict strong phase transitions to occur at very high nuclear densities only.

APA, Harvard, Vancouver, ISO, and other styles

16

Uechi, Schun T., and Hiroshi Uechi. "The Density-Dependent Correlations among Observables in Nuclear Matter and Hyperon-Rich Neutron Stars." Advances in High Energy Physics 2009 (2009): 1–15. http://dx.doi.org/10.1155/2009/640919.

Full text

Abstract:

The conservingσ-ω-ρmean-field approximation with nonlinear interactions of hadrons has been applied to examine properties of nuclear matter and hyperonic neutron stars. The nonlinear interactions that will produce density-dependent effective masses and coupling constants of hadrons are included in order to examine density correlations among properties of nuclear matter and neutron stars such as binding energy, incompressibility,K, symmetry energy,a4, hyperon-onset density, and maximum masses of neutron stars. The conditions of conserving approximations in order to maintain thermodynamic consistency to an approximation are essential for the analysis of density-dependent correlations.

APA, Harvard, Vancouver, ISO, and other styles

17

Deich, W. T. S., and S. R. Kulkarni. "The Masses of the Neutron Stars in M15C." Symposium - International Astronomical Union 165 (1996): 279–85. http://dx.doi.org/10.1017/s0074180900055741.

Full text

Abstract:

Several years of timing the pulsar in the binary neutron star system M15C have yielded the masses of both stars: the total mass is MT = 2.7121(6) M⊙; the companion mass is mc = 1.36(4) M⊙; and the pulsar mass is mp = 1.35(4) M⊙. We argue that this system is not likely to have formed through accretion-induced collapse (AIC), and that the standard model also has problems in explaining the formation.

APA, Harvard, Vancouver, ISO, and other styles

18

Heiselberg, H., and M. Hjorth-Jensen. "Phase Transitions in Neutron Stars and Maximum Masses." Astrophysical Journal 525, no. 1 (November 1, 1999): L45—L48. http://dx.doi.org/10.1086/312321.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Zöllner, Rico, Minghui Ding, and Burkhard Kämpfer. "Masses of Compact (Neutron) Stars with Distinguished Cores." Particles 6, no. 1 (February 2, 2023): 217–38. http://dx.doi.org/10.3390/particles6010012.

Full text

Abstract:

In this paper, the impact of core mass on the compact/neutron-star mass-radius relation is studied. Besides the mass, the core is parameterized by its radius and surface pressure, which supports the outside one-component Standard Model (SM) matter. The core may accommodate SM matter with unspecified (or poorly known) equation-of-state or several components, e.g., consisting of admixtures of Dark Matter and/or Mirror World matter etc. beyond the SM. Thus, the admissible range of masses and radii of compact stars can be considerably extended.

APA, Harvard, Vancouver, ISO, and other styles

20

Karakas, Amanda I. "Nucleosynthesis in stars: The Origin of the Heaviest Elements." Proceedings of the International Astronomical Union 14, S343 (August 2018): 79–88. http://dx.doi.org/10.1017/s1743921318006166.

Full text

Abstract:

AbstractThe chemical evolution of the Universe is governed by the nucleosynthesis contribution from stars, which in turn is determined primarily by the initial stellar mass. The heaviest elements are primarily produced through neutron capture nucleosynthesis. Two main neutron capture processes identified are the slow and rapid neutron capture processes (s and r processes, respectively). The sites of the r and s-process are discussed, along with recent progress and their associated uncertainties. This review is mostly focused on the s-process which occurs in low and intermediate-mass stars which have masses up to about 8 solar masses (M⊙). We also discuss the intermediate-neutron capture process (or i-process), which may occur in AGB stars, accreting white dwarfs, and massive stars. The contribution of the i-process to the chemical evolution of elements in galaxies is as yet uncertain.

APA, Harvard, Vancouver, ISO, and other styles

21

GIUDICE, E. DEL, R. MELE, G. PREPARATA, C. GUALDI, G. MANGANO, and G. MIELE. "NEUTRON STARS AND THE COHERENT NUCLEAR INTERACTION." International Journal of Modern Physics D 04, no. 04 (August 1995): 531–48. http://dx.doi.org/10.1142/s0218271895000375.

Full text

Abstract:

In the framework of a novel approach to the dynamics of nuclei and large collections of nucleons, which fully exploits the coherent interaction among π’s, nucleons and Δ’s, we derive a new equation of state for neutronic matter. By introducing it in the Tolman-Oppenheimer-Volkof equations we derive the masses and radii of neutron stars as a function of the central density. We obtain a maximum mass Mmax≃2.7 Mʘ and a minimum period of rotation Tmin=0.8 msec.

APA, Harvard, Vancouver, ISO, and other styles

22

Lee, Chang-Hwan. "Formation and Evolution of Neutron Star Binaries: Masses of Neutron Stars." EPJ Web of Conferences 20 (2012): 04002. http://dx.doi.org/10.1051/epjconf/20122004002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Menezes, Débora Peres. "A Neutron Star Is Born." Universe 7, no. 8 (July 26, 2021): 267. http://dx.doi.org/10.3390/universe7080267.

Full text

Abstract:

A neutron star was first detected as a pulsar in 1967. It is one of the most mysterious compact objects in the universe, with a radius of the order of 10 km and masses that can reach two solar masses. In fact, neutron stars are star remnants, a kind of stellar zombie (they die, but do not disappear). In the last decades, astronomical observations yielded various contraints for neutron star masses, and finally, in 2017, a gravitational wave was detected (GW170817). Its source was identified as the merger of two neutron stars coming from NGC 4993, a galaxy 140 million light years away from us. The very same event was detected in γ-ray, X-ray, UV, IR, radio frequency and even in the optical region of the electromagnetic spectrum, starting the new era of multi-messenger astronomy. To understand and describe neutron stars, an appropriate equation of state that satisfies bulk nuclear matter properties is necessary. GW170817 detection contributed with extra constraints to determine it. On the other hand, magnetars are the same sort of compact object, but bearing much stronger magnetic fields that can reach up to 1015 G on the surface as compared with the usual 1012 G present in ordinary pulsars. While the description of ordinary pulsars is not completely established, describing magnetars poses extra challenges. In this paper, I give an overview on the history of neutron stars and on the development of nuclear models and show how the description of the tiny world of the nuclear physics can help the understanding of the cosmos, especially of the neutron stars.

APA, Harvard, Vancouver, ISO, and other styles

24

SILVERMAN, M. P. "QUANTUM CONDENSATES IN EXTREME GRAVITY: IMPLICATIONS FOR COLD STARS AND DARK MATTER." International Journal of Modern Physics D 17, no. 03n04 (March 2008): 603–9. http://dx.doi.org/10.1142/s0218271808012334.

Full text

Abstract:

Stable end-point stars currently fall into two distinct classes — white dwarfs and neutron stars — differing enormously in central density and radial size. No stable cold dead stars are thought to span the intervening densities or have masses beyond ~2–3 solar masses. I show, however, that the general-relativistic condition of hydrostatic equilibrium augmented by the equation of state of a neutron condensate at 0 K generates stable sequences of cold stars that span the density gap and can have masses well beyond prevailing limits. The radial sizes and mass limit of each sequence are determined by the mass and scattering length of the composite bosons. Solutions for hypothetical bosons of ultrasmall mass and large scattering length yield huge self-gravitating systems of low density, resembling galactic dark matter halos.

APA, Harvard, Vancouver, ISO, and other styles

25

Pavlov, G. G., and V. E. Zavlin. "Thermal Radiation from Isolated Neutron Stars." Symposium - International Astronomical Union 195 (2000): 103–12. http://dx.doi.org/10.1017/s0074180900162837.

Full text

Abstract:

The analysis of thermal radiation emitted from the atmospheres of isolated neutron stars allows one to measure their surface temperatures, magnetic fields, masses, and radii, as well as the chemical composition of their atmospheres. Thus, multiwavelength observations of this radiation provide an important tool for studying the structure and evolution of neutron stars and for elucidating properties of the superdense matter in their interiors. We describe recent theoretical and observational results on thermal radiation from radio pulsars and radio-quiet neutron stars and discuss their astrophysical implications.

APA, Harvard, Vancouver, ISO, and other styles

26

Vidaña, Isaac. "Neutron stars and the hyperon puzzle." EPJ Web of Conferences 271 (2022): 09001. http://dx.doi.org/10.1051/epjconf/202227109001.

Full text

Abstract:

In this work we shortly review the so-called “hyperon puzzle”, i.e., the problem of the strong softening of the equation of state of dense matter induced by the presence of hyperons which leads to maximum masses of neutron stars incompatible with the recent observations of ∼ 2 M⊙ millisecond pulsars. In particular, we briefly go through some of the possible solutions that have been proposed to tackle this still open problem.

APA, Harvard, Vancouver, ISO, and other styles

27

Astashenok, Artyom V., and Sergey D. Odintsov. "Rotating neutron stars in F(R) gravity with axions." Monthly Notices of the Royal Astronomical Society 498, no. 3 (August 29, 2020): 3616–23. http://dx.doi.org/10.1093/mnras/staa2630.

Full text

Abstract:

ABSTRACT We investigate equilibrium configurations of uniformly rotating neutron stars in R2 gravity with axion scalar field for GM1 equation of state (EoS) for nuclear matter. The mass–radius diagram, mass–central energy density are presented for some frequencies in comparison with static stars. We also compute equatorial and polar radii and moment of inertia for stars. For axion field ϕ, the coupling in the form ∼R2ϕ is assumed. Several interesting results follow from our consideration. Maximal possible star mass with given EoS increases due to the contribution of coupling term. We discovered the possibility to increase maximal frequency of the rotation in comparison with General Relativity. As a consequence, the lower bound on mass of the fast rotating stars decreases. For frequency f = 700 Hz, neutron stars with masses ∼M⊙ can exist for some choice of parameters (in General Relativity for same EoS, this limit is around 1.2 M⊙). Another feature of our solutions is relatively small increase of stars' radii for high frequencies in comparison with static case. Thus, eventually, the new class of neutron stars in R2 gravity with axions is discovered namely fast rotating compact stars with intermediate masses.

APA, Harvard, Vancouver, ISO, and other styles

28

Zubairi, Omair, David Wigley, and Fridolin Weber. "Stellar Structure Models of Deformed Neutron Stars." International Journal of Modern Physics: Conference Series 45 (January 2017): 1760029. http://dx.doi.org/10.1142/s2010194517600291.

Full text

Abstract:

Traditional stellar structure models of non-rotating neutron stars work under the assumption that these stars are perfect spheres. This assumption of perfect spherical symmetry is not correct if the matter inside neutron stars is described by an anisotropic model for the equation of state. Certain classes of neutron stars such as Magnetars and neutron stars which contain color-superconducting quark matter cores are expected to be deformed making them oblong spheroids. In this work, we investigate the stellar structure of these deformed neutron stars by deriving stellar structure equations in the framework of general relativity. Using a non-isotropic equation of state model, we solve these structure equations numerically in two dimensions. We calculate stellar properties such as masses and radii along with pressure profiles and investigate changes from standard spherical models.

APA, Harvard, Vancouver, ISO, and other styles

29

Szewczyk, Paweł, Dorota Gondek-Rosińska, Kamil Kolasa, and Parita Mehta. "Are hypermassive neutron stars stable against a prompt collapse?" Proceedings of the International Astronomical Union 16, S363 (June 2020): 350–51. http://dx.doi.org/10.1017/s1743921322000977.

Full text

Abstract:

AbstractDifferential rotation in neutron stars allows for significantly larger masses than rigid rotation. Some of those hypermassive objects are, however, unstable and collapse to a black hole immediately after formation. Yet, the exact threshold of dynamical stability is still unknown.In our work we explore the limits on masses of neutron stars with various degrees of differential rotation which could be stable against a prompt collapse to a black hole by using turning-point (j-constant) criterion. We considered both spheroidal and quasi-toroidal differentially rotating neutron stars described by the polytropic equation of state. We find that massive configurations could be temporarily stabilized by differential rotation. Such objects are important sources of gravitational waves. Our results are a starting point for more detailed studies of stability using hydrodynamical codes.

APA, Harvard, Vancouver, ISO, and other styles

30

Bejger, Michał, Morgane Fortin, Paweł Haensel, and J. Leszek Zdunik. "Formation of millisecond pulsars - NS initial mass and EOS constraints." Proceedings of the International Astronomical Union 8, S290 (August 2012): 109–12. http://dx.doi.org/10.1017/s174392131201931x.

Full text

Abstract:

AbstractRecent measurement of a high millisecond pulsar mass (PSR J1614-2230, 1.97± 0.04 M⊙) compared with the low mass of PSR J0751+1807 (1.26± 0.14 M⊙) indicates a large span of masses of recycled pulsars and suggests a broad range of neutron stars masses at birth. We aim at reconstructing the pre-accretion masses for these pulsars while taking into account interaction of the magnetic field with a thin accretion disk, magnetic field decay and relativistic 2D solutions for stellar configurations for a set of equations of state. We briefly discuss the evolutionary scenarios leading to the formation of these neutron stars and study the influence of the equation of state.

APA, Harvard, Vancouver, ISO, and other styles

31

Filimonov, V. A. "Masses of neutron stars with a solid internal shell." Soviet Physics Journal 29, no. 2 (February 1986): 120–23. http://dx.doi.org/10.1007/bf00896347.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Caspar, G., I. Rodríguez, P. O. Hess, and W. Greiner. "Vacuum fluctuation inside a star and their consequences for neutron stars, a simple model." International Journal of Modern Physics E 25, no. 04 (April 2016): 1650027. http://dx.doi.org/10.1142/s0218301316500270.

Full text

Abstract:

Applying semi-classical quantum mechanics, the vacuum fluctuations within a star are determined, assuming a constant mass density and applying a monopole approximation. It is found that the density for the vacuum fluctuations does not only depend linearly on the mass density, as assumed in a former publication, where neutron stars up to 6 solar masses were obtained. This is used to propose a simple model on the dependence of the dark energy to the mass density, as a function of the radial distance [Formula: see text]. It is shown that stars with up to 200 solar masses can, in principle, be obtained. Though, we use a phenomenological model, it shows that in the presence of vacuum fluctuations stars with large masses can be stabilized and probably stars up to any mass can exist, which usually are identified as black holes.

APA, Harvard, Vancouver, ISO, and other styles

33

BEDNAREK, ILONA, and RYSZARD MANKA. "STRUCTURE AND PROPERTIES OF NEUTRON STARS IN THE RELATIVISTIC MEAN-FIELD THEORY." International Journal of Modern Physics D 10, no. 05 (October 2001): 607–24. http://dx.doi.org/10.1142/s0218271801001104.

Full text

Abstract:

Properties of rotating neutron stars with the use of relativistic mean-field theory are considered. The performed analysis of neutron star matter is based on the nonlinear Lgrangian density. The presence of nonlinear interaction of vector mesons modifies the density dependence of the ρ field and influences bulk parameters of neutron stars. The observed quasiperiodic X-ray oscillations of low mass X-ray binaries can be used in order to constrain the equation of state of neutron star matter. Having assumed that the maximum frequency of the quasiperiodic oscillations originates at the circular orbit it is possible to estimate masses and radii of neutron stars.

APA, Harvard, Vancouver, ISO, and other styles

34

Pols, Onno R., and Jasinta D. M. Dewi. "Helium-star Mass Loss and Its Implications for Black Hole Formation and Supernova Progenitors." Publications of the Astronomical Society of Australia 19, no. 2 (2002): 233–37. http://dx.doi.org/10.1071/as01121.

Full text

Abstract:

AbstractRecently the observationally derived stellar-wind mass-loss rates for Wolf-Rayet stars, or massive naked helium stars, have been revised downwards by a substantial amount. We present evolutionary calculations of helium stars incorporating such revised mass-loss rates, as well as mass transfer to a close compact binary companion. Our models reach final masses well in excess of 10 M⊙, consistent with the observed masses of black holes in X-ray binaries. This resolves the discrepancy found with previously assumed high mass-loss rates between the final masses of stars which spend most of their helium-burning lifetime as Wolf-Rayet stars (˜3 M⊙) and the minimum observed black hole masses (6 M⊙). Our calculations also suggest that there are two distinct classes of progenitors for Type Ic supernovae: one with very large initial masses (35 M⊙), which are still massive when they explode and leave black hole remnants, and one with moderate initial masses (˜12–20 M⊙) undergoing binary interaction, which end up with small pre-explosion masses and leave neutron star remnants.

APA, Harvard, Vancouver, ISO, and other styles

35

Naya, Carlos. "Neutron stars within the Skyrme model." International Journal of Modern Physics E 28, no. 08 (August 2019): 1930006. http://dx.doi.org/10.1142/s0218301319300066.

Full text

Abstract:

The Skyrme model is a low energy effective field theory of strong interactions where nuclei and baryons appear as collective excitations of pionic degrees of freedom. In the last years, there has been a revival of Skyrme’s ideas and new related models, and some of them with BPS bounds (topological lower energy bounds) have been proposed. It is the aim of this paper to review how they can be applied to the study of neutron stars allowing for a description by means of topological solitons. We will focus on different aspects as the equation of state or the mass-radius relation, where we find that high maximal masses are supported.

APA, Harvard, Vancouver, ISO, and other styles

36

VALENTIM, RODOLFO, JORGE E. HORVATH, and ERALDO M. RANGEL. "BAYESIAN ANALYSIS OF THE MASS DISTRIBUTION OF NEUTRON STARS." International Journal of Modern Physics E 20, supp01 (December 2011): 203–7. http://dx.doi.org/10.1142/s0218301311040268.

Full text

Abstract:

The distribution of masses for neutron stars is analyzed using the Bayesian statistical inference, evaluating the likelihood of two a priori gaussian peaks distribution by using fifty-five measured points obtained in a variety of systems. The results strongly suggest the existence of a bimodal distribution of the masses, with the first peak around 1.35M⊙ ± 0.06 M ⊙ and a much wider second peak at 1.73M⊙ ± 0.36 M ⊙. We compared the two gaussian's model centered at 1.35M⊙ and 1.55M⊙ against a "single gaussian" model with 1.50M⊙ ± 0.11 M ⊙ using 3σ that provided a wide peak covering objects the full range of observed of masses. In order to compare models, BIC (Baysesian Information Criterion) can be used and a strong evidence for two distributions model against one peak model was found. The results support earlier views related to the different evolutionary histories of the members for the first two peaks, which produces a natural separation (in spite that no attempt to "label" the systems has been made). However, the recently claimed low-mass group, possibly related to O - Mg - Ne core collapse events, has a monotonically decreasing likelihood and has not been identified within this sample.

APA, Harvard, Vancouver, ISO, and other styles

37

Matsuo, Yasuhide, HeLei Liu, Masa-aki Hashimoto, and Tsuneo Noda. "Quiescent luminosities of accreting neutron stars-possibility of neutrino losses due to strong pion condensations." International Journal of Modern Physics E 27, no. 08 (August 2018): 1850067. http://dx.doi.org/10.1142/s0218301318500672.

Full text

Abstract:

We construct the quiescent neutron star models in the evolutionary calculations. The X-ray luminosities have been derived in terms of the time-averaged mass accretion rate for various neutron star masses and surface compositions. We compare the quiescent luminosities observed from X-ray transients in low mass X-ray binaries, where the stellar evolutionary calculations of accreting neutron stars include neutrino cooling due to strong pion condensations. Our results based on the evolutionary calculations suggest that stronger cooling process would be necessary to be consistent with observations.

APA, Harvard, Vancouver, ISO, and other styles

38

Sales, Thiago, Odilon Lourenço, Mariana Dutra, and Rodrigo Negreiros. "Revisiting the thermal relaxation of neutron stars." Astronomy & Astrophysics 642 (October 2020): A42. http://dx.doi.org/10.1051/0004-6361/202038193.

Full text

Abstract:

In this work, we revisit the thermal relaxation process for neutron stars. Such a process is associated with the thermal coupling between the core and the crust of neutron stars. The thermal relaxation, which takes place at around 10–100 years, is manifested as a sudden drop in the star’s surface temperature. Such a drop is smooth for slowly cooling objects and very sharp for fast-cooling ones. In our study, we focused particularly on the cooling of neutron stars whose mass is slightly greater than the value above which the direct Urca (DU) process sets in. Considering different mechanisms for neutrino production in each region of the star, and working with equations of state with different properties, we solved the thermal evolution equation and calculated the thermal relaxation time for an ample range of neutron star masses. By performing a comprehensive study of neutron stars just above the onset of the DU process, we show that stars under these conditions exhibit a peculiar thermal relaxation behavior. We demonstrate that such stars exhibit an abnormally late relaxation time, characterized by a second drop in its surface temperature taking place a later age. We qualified such behavior by showing that it is associated with limited spatial distribution of the DU process in such stars. We show that as the star’s mass increases, the DU region also grows, and the star exhibits the expected behavior of fast-cooling stars. Finally, we show that one can expect high relaxation times for stars in which the DU process takes place in a radius no larger than 3 km.

APA, Harvard, Vancouver, ISO, and other styles

39

Mandel, Ilya, Bernhard Müller, Jeff Riley, Selma E. de Mink, Alejandro Vigna-Gómez, and Debatri Chattopadhyay. "Binary population synthesis with probabilistic remnant mass and kick prescriptions." Monthly Notices of the Royal Astronomical Society 500, no. 1 (October 31, 2020): 1380–84. http://dx.doi.org/10.1093/mnras/staa3390.

Full text

Abstract:

ABSTRACT We report on the impact of a probabilistic prescription for compact remnant masses and kicks on massive binary population synthesis. We find that this prescription populates the putative mass gap between neutron stars and black holes with low-mass black holes. However, evolutionary effects reduce the number of X-ray binary candidates with low-mass black holes, consistent with the dearth of such systems in the observed sample. We further find that this prescription is consistent with the formation of heavier binary neutron stars such as GW190425, but overpredicts the masses of Galactic double neutron stars. The revised natal kicks, particularly increased ultra-stripped supernova kicks, do not directly explain the observed Galactic double neutron star orbital period–eccentricity distribution. Finally, this prescription allows for the formation of systems similar to the recently discovered extreme mass ratio binary GW190814, but only if we allow for the survival of binaries in which the common envelope is initiated by a donor crossing the Hertzsprung gap, contrary to our standard model.

APA, Harvard, Vancouver, ISO, and other styles

40

Vidaña, Isaac. "Short introduction to the physics of neutron stars." EPJ Web of Conferences 227 (2020): 01018. http://dx.doi.org/10.1051/epjconf/202022701018.

Full text

Abstract:

Here we briefly review several aspects of the physics of neutron stars.In particular, we shortly describe the different types of telescopes employed in their observation, the many astrophysical manifestations of these objects and the measurement of observables such as their masses and radii. A brief summary of their composition, structure equations and equation of state is also presented.

APA, Harvard, Vancouver, ISO, and other styles

41

PSONIS, V. P., CH C. MOUSTAKIDIS, and S. E. MASSEN. "NUCLEAR SYMMETRY ENERGY EFFECTS ON NEUTRON STARS PROPERTIES." Modern Physics Letters A 22, no. 17 (June 7, 2007): 1233–53. http://dx.doi.org/10.1142/s0217732307023572.

Full text

Abstract:

We construct a class of nuclear equations of state based on a schematic potential model, that originates from the work of Prakash et al.,1 which reproduce the results of most microscopic calculations. The equations of state are used as input for solving the Tolman–Oppenheimer–Volkov equations for the corresponding neutron stars. The potential part contribution of the symmetry energy to the total energy is parametrized in a generalized form both for low and high values of the baryon density. Special attention is devoted to the construction of the symmetry energy in order to reproduce the results of most microscopic calculations of dense nuclear matter. The obtained nuclear equations of state are applied for the systematic study of the global properties of a neutron star (masses, radii and composition). The calculated masses and radii of the neutron stars are plotted as a function of the potential part parameters of the symmetry energy. A linear relation between these parameters, the radius and the maximum mass of the neutron star is obtained. In addition, a linear relation between the radius and the derivative of the symmetry energy near the saturation density is found. We also address the problem of the existence of correlation between the pressure near the saturation density and the radius.

APA, Harvard, Vancouver, ISO, and other styles

42

Mariani, Mauro, Milva Orsaria, and Héctor Vucetich. "Simplified Thermal Evolution of Proto-Hybrid Stars." International Journal of Modern Physics: Conference Series 45 (January 2017): 1760041. http://dx.doi.org/10.1142/s2010194517600412.

Full text

Abstract:

We study the possibility of a hadron-quark phase transition in the interior of neutron stars, taking into account different schematic evolutionary stages at finite temperature. Furthermore, we analyze the astrophysical properties of hot and cold hybrid stars, considering the constraint on maximum mass given by the pulsars J1614-2230 and J1614-2230. We obtain cold hybrid stars with maximum masses [Formula: see text] M[Formula: see text]. Our study also suggest that during the proto-hybrid star evolution a late phase transition between hadronic matter and quark matter could occur, in contrast with previous studies of proto-neutron stars.

APA, Harvard, Vancouver, ISO, and other styles

43

Özel, Feryal, and Paulo Freire. "Masses, Radii, and the Equation of State of Neutron Stars." Annual Review of Astronomy and Astrophysics 54, no. 1 (September 19, 2016): 401–40. http://dx.doi.org/10.1146/annurev-astro-081915-023322.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Özel, Feryal, Dimitrios Psaltis, Ramesh Narayan, and Antonio Santos Villarreal. "ON THE MASS DISTRIBUTION AND BIRTH MASSES OF NEUTRON STARS." Astrophysical Journal 757, no. 1 (September 5, 2012): 55. http://dx.doi.org/10.1088/0004-637x/757/1/55.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Bogomazov, A. I. "Evolution of the Masses of Neutron Stars in Binary Systems." Astronomy Reports 49, no. 4 (2005): 295. http://dx.doi.org/10.1134/1.1898407.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

RAZEIRA, MOISÉS, ALEXANDRE MESQUITA, CÉSAR A. Z. VASCONCELLOS, ROSANA O. GOMES, AURORA PÉREZ MARTÍNEZ, HUGO PÉREZ ROJAS, and DARYEL MANREZA PARET. "RELATIVISTIC URCA PROCESSES IN NEUTRON STARS WITH AN ANTIKAON CONDESATE." International Journal of Modern Physics E 20, supp02 (December 2011): 146–51. http://dx.doi.org/10.1142/s0218301311040724.

Full text

Abstract:

A recently developed effective relativistic theory for nuclear matter is applied to the description of the cooling process of baryon degenerate neutron star matter through neutrino emission considering direct URCA processes. In our approach nucleons and antikaon condensates interact with σ, ω, ρ, δ and ς meson fields. Our results indicate a substantial decrease of the critical threshold density for the URCA process. This is because the presence of these interacting degrees of freedom increase the proportion of protons, producing simultaneously the reduction of the isospin asymmetry in nuclear matter. Our results also indicate that neutron stars with larger masses than MNE ~ 0.9M⊙, which represents the stellar critical threshold (the mass of the neutron star whose baryon central density reached the critical density) would be cooled efficiently and be outside the possibility of observation by heat radiation in a few years.

APA, Harvard, Vancouver, ISO, and other styles

47

Dai, Shi, and Renxin Xu. "Microlensing pulsars." Proceedings of the International Astronomical Union 8, S291 (August 2012): 369–71. http://dx.doi.org/10.1017/s1743921312024155.

Full text

Abstract:

AbstractWe propose to determine the mass of isolated neutron stars through gravitational microlensing. We show that the all-sky microlensing pulsar event rate is ~2.8 × 10−10 per year per background source (/yr/source). Microlensing neutron star event rate would contribute ~20% to the total Galactic event rate at time-scale of ~15 days. We also present catalogue comparisons between known pulsars and background stars. We find that several pulsars would pass by background stars closely and may cause observable astrometric microlensing phenomenon. According to our covariance analysis, the uncertainty of masses determined through astrometric microlensing could be ~20%. Therefore, gravitational microlensing is a promising way to determine the mass of isolated neutron stars with future advanced radio and optical telescopes.

APA, Harvard, Vancouver, ISO, and other styles

48

Koliogiannis Koutmiridis, Polychronis, and Charalampos Moustakidis. "Towards the Keplerian sequence: Realistic equations of state in rapidly rotating neutron stars." HNPS Proceedings 27 (April 17, 2020): 85. http://dx.doi.org/10.12681/hnps.2987.

Full text

Abstract:

Neutron stars are among the densest known objects in the universe and an ideal laboratory for the strange physics of super-condensed matter. In the present work, we investigate the Keplerian (mass-shedding) sequence of rotating neutron stars by employing realistic equations of state based on various theoretical nuclear models. In particular, we compute the moment of inertia and angular momentum of neutron stars against mass-shedding and secular axisymmetric instability. We mainly focus on the dependence of these properties from the bulk properties of neutron stars. Another property that studied in detail, is the dimensionless spin parameter (kerr parameter) of rotating neutron stars at the mass-shedding limit. In addition, supramassive time evolutionary rest mass sequences, which have their origin in general relativity, are explored. Supramassive sequences have masses exceeding the maximum mass of a non-rotating neutron star and evolve toward catastrophic collapse to a black hole. Important information can be gained from the astrophysical meaning of the kerr parameter and the supramassive sequences in neutron stars. Finally, the effects of the Keplerian sequence, in connection with the latter, may provide us constraints on the high density part of the equation of state of cold neutron star matter.

APA, Harvard, Vancouver, ISO, and other styles

49

CEA, PAOLO. "P-STARS." International Journal of Modern Physics D 13, no. 09 (October 2004): 1917–26. http://dx.doi.org/10.1142/s0218271804005833.

Full text

Abstract:

P-Stars are a new class of compact stars made of up and down quarks in β-equilibrium with electrons in an Abelian chromomagnetic condensate. We show that P-Stars are able to account for compact stars with R≲6 Km , as well as stars with radius comparable with canonical Neutron Stars. We find that cooling curves of P-Stars compare rather well with observational data. We suggest that P-Matter produced at the primordial deconfinement transition is a viable candidate for baryonic Cold Dark Matter. Finally, we show that P-Stars are able to overcome the gravitational collapse even for masses much greater than 106 M⊙.

APA, Harvard, Vancouver, ISO, and other styles

50

Viñas, Xavier, Claudia Gonzalez-Boquera, Mario Centelles, Chiranjib Mondal, and Luis M. Robledo. "Unified Equation of State for Neutron Stars Based on the Gogny Interaction." Symmetry 13, no. 9 (September 2, 2021): 1613. http://dx.doi.org/10.3390/sym13091613.

Full text

Abstract:

The effective Gogny interactions of the D1 family were established by D. Gogny more than forty years ago with the aim to describe simultaneously the mean field and the pairing field corresponding to the nuclear interaction. The most popular Gogny parametrizations, namely D1S, D1N and D1M, describe accurately the ground-state properties of spherical and deformed finite nuclei all across the mass table obtained with Hartree–Fock–Bogoliubov (HFB) calculations. However, these forces produce a rather soft equation of state (EoS) in neutron matter, which leads to predict maximum masses of neutron stars well below the observed value of two solar masses. To remove this limitation, we built new Gogny parametrizations by modifying the density dependence of the symmetry energy predicted by the force in such a way that they can be applied to the neutron star domain and can also reproduce the properties of finite nuclei as good as their predecessors. These new parametrizations allow us to obtain stiffer EoS’s based on the Gogny interactions, which predict maximum masses of neutron stars around two solar masses. Moreover, other global properties of the star, such as the moment of inertia and the tidal deformability, are in harmony with those obtained with other well tested EoSs based on the SLy4 Skyrme force or the Barcelona–Catania–Paris–Madrid (BCPM) energy density functional. Properties of the core-crust transition predicted by these Gogny EoSs are also analyzed. Using these new Gogny forces, the EoS in the inner crust is obtained with the Wigner–Seitz approximation in the Variational Wigner–Kirkwood approach along with the Strutinsky integral method, which allows one to estimate in a perturbative way the proton shell and pairing corrections. For the outer crust, the EoS is determined basically by the nuclear masses, which are taken from the experiments, wherever they are available, or by HFB calculations performed with these new forces if the experimental masses are not known.

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!