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Journal articles on the topic 'Neutron stars'

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Author: Grafiati

Published: 4 June 2021

Last updated: 29 July 2024

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1

Wang, Zhen-Ru. "Ancient Guest Stars as Harbingers of Neutron Star Formation." Symposium - International Astronomical Union 125 (1987): 305–18. http://dx.doi.org/10.1017/s0074180900160917.

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It was just after the discovery of neutrons in 1932, Landau suggested the possibility of compact stars composed of neutrons. In 1934 Baade and Zwicky proposed the idea of neutron stars independently and suggested that neutron stars would be formed in supernova explosions.

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2

Woltjer, L. "Where Neutron Stars Come From, How Neutron Stars Evolve, and Neutron Stars Go." Symposium - International Astronomical Union 125 (1987): 559–62. http://dx.doi.org/10.1017/s007418090016142x.

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3

Yakovlev, D. "Neutrino emission from neutron stars." Physics Reports 354, no. 1-2 (November 2001): 1–155. http://dx.doi.org/10.1016/s0370-1573(00)00131-9.

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4

Kolomeitsev, E. E., and D. N. Voskresensky. "Neutrino Processes in Neutron Stars." EPJ Web of Conferences 7 (2010): 03003. http://dx.doi.org/10.1051/epjconf/20100703003.

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5

Seward, F. "Neutron Stars." Science 262, no. 5132 (October 15, 1993): 444–45. http://dx.doi.org/10.1126/science.262.5132.444.

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6

Vartanyan, Yu L., and G. B. Alaverdyan. "Neutron stars." Astrophysics 31, no. 1 (1990): 482–89. http://dx.doi.org/10.1007/bf01004395.

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7

Ho, Wynn C. G., Craig O. Heinke, Daniel J. Patnaude, Peter S. Shternin, and Dmitry G. Yakovlev. "Hottest Superfluid and Superconductor in the Universe: Lessons from the Cooling of the Cassiopeia A Neutron Star." Proceedings of the International Astronomical Union 7, S285 (September 2011): 337–39. http://dx.doi.org/10.1017/s1743921312000981.

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AbstractThe cooling rate of young neutron stars gives direct insight into their internal makeup. Using Chandra observations of the 330-year-old Cassiopeia A supernova remnant, we find that the temperature of the youngest-known neutron star in the Galaxy has declined by 4% over the last 10 years. The decline is explained naturally by superconductivity and superfluidity of the protons and neutrons in the stellar core. The protons became superconducting early in the life of the star and suppressed the early cooling rate; the neutron star thus remained hot before the (recent) onset of neutron superfluidity. Once the neutrons became superfluid, the Cooper pair-formation process produced a splash of neutrino emission which accelerated the cooling and resulted in the observed rapid temperature decline. This is the first time a young neutron star has been seen to cool in real time, and is the first direct evidence, from cooling observations, of superfluidity and superconductivity in the core of neutron stars.

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8

Yakovlev, D. G. "Non-equilibrium neutron stars." International Journal of Modern Physics A 35, no. 02n03 (January 30, 2020): 2040049. http://dx.doi.org/10.1142/s0217751x20400497.

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Neutron stars contain superdense matter in their interiors. Characteristic densities in their cores are several times higher than the standard density of nuclear matter. This matter is so dense that it would be natural to assume that frequent particle collisions produce immediate equilibration. However, because of the slowness of some reactions, the equilibration with respect to them can be greatly delayed. Then one should deal with non-equilibrium stars which contain extra energy to be released. Deviations from equilibrium can affect neutrino emission of neutron stars, warm up their interiors and influence their thermal evolution. The effects of equilibration can be important for pulsating, rotating, accreting neutron stars, as well as for merging binary neutron stars.

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9

Chakraborty, Sabyasachi, Aritra Gupta, and Miguel Vanvlasselaer. "Anomaly induced cooling of neutron stars: a Standard Model contribution." Journal of Cosmology and Astroparticle Physics 2023, no. 10 (October 1, 2023): 030. http://dx.doi.org/10.1088/1475-7516/2023/10/030.

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Abstract Young neutron stars cool via the emission of neutrinos from their core. A precise understanding of all the different processes producing neutrinos in the hot and degenerate matter is essential for assessing the cooling rate of such stars. The main Standard Model processes contributing to this effect are ν bremsstrahlung, mURCA among others. In this paper, we investigate another Standard Model process initiated by the Wess-Zumino-Witten term, leading to the emission of neutrino pairs via Nγ → Nνν̅. We find that for proto-neutron stars, such processes with degenerate neutrons can be comparable and even dominate over the typical and well-known cooling mechanisms.

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10

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.

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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.

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11

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

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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.

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12

Gondek-Rosińska, D., P. Haensel, and J. L. Zdunik. "Protoneutron stars and neutron stars." International Astronomical Union Colloquium 177 (2000): 663–64. http://dx.doi.org/10.1017/s0252921100060942.

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AbstractWe find constraints on minimum and maximum mass of ordinary neutron stars imposed by their early evolution (protoneutron star stage). We calculate models of protoneutron stars using a realistic standard equation of state of hot, dense matter valid for both supranuclear and subnuclear densities. Results for different values of the nuclear incompressibility are presented.

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13

Bahcall, Safi, Bryan W. Lynn, and Stephen B. Selipsky. "Are neutron stars Q-stars?" Nuclear Physics B 331, no. 1 (February 1990): 67–79. http://dx.doi.org/10.1016/0550-3213(90)90018-9.

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14

Zhou, Dake. "Neutron Star Constraints on Neutron Dark Decays." Universe 9, no. 11 (November 17, 2023): 484. http://dx.doi.org/10.3390/universe9110484.

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Motivated by the neutron lifetime puzzle, it is proposed that neutrons may decay into new states yet to be observed. We review the neutron star constraints on dark fermions carrying unit baryon number with masses around 939 MeV, and discuss the interaction strengths required for the new particle. The possibility of neutrons decaying into three dark fermions is investigated. While up to six flavors of dark quarks with masses around 313 MeV can be compatible with massive pulsars, any such exotic states lighter than about 270 MeV are excluded by the existence of low-mass neutron stars around ∼1.2M⊙. Light dark quarks in the allowed mass range may form a halo surrounding normal neutron stars. We discuss the potential observable signatures of the halo during binary neutron star mergers.

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15

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.

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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.

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16

Salmonson, Jay D., and James R. Wilson. "Neutrino Annihilation between Binary Neutron Stars." Astrophysical Journal 561, no. 2 (November 10, 2001): 950–56. http://dx.doi.org/10.1086/323319.

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17

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.

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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.

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18

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.

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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.

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19

Manuel, Cristina, and Laura Tolos. "Transport Properties of Superfluid Phonons in Neutron Stars." Universe 7, no. 3 (March 5, 2021): 59. http://dx.doi.org/10.3390/universe7030059.

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We review the effective field theory associated with the superfluid phonons that we use for the study of transport properties in the core of superfluid neutrons stars in their low temperature regime. We then discuss the shear and bulk viscosities together with the thermal conductivity coming from the collisions of superfluid phonons in neutron stars. With regard to shear, bulk, and thermal transport coefficients, the phonon collisional processes are obtained in terms of the equation of state and the superfluid gap. We compare the shear coefficient due to the interaction among superfluid phonons with other dominant processes in neutron stars, such as electron collisions. We also analyze the possible consequences for the r-mode instability in neutron stars. As for the bulk viscosities, we determine that phonon collisions contribute decisively to the bulk viscosities inside neutron stars. For the thermal conductivity resulting from phonon collisions, we find that it is temperature independent well below the transition temperature. We also obtain that the thermal conductivity due to superfluid phonons dominates over the one resulting from electron-muon interactions once phonons are in the hydrodynamic regime. As the phonons couple to the Z electroweak gauge boson, we estimate the associated neutrino emissivity. We also briefly comment on how the superfluid phonon interactions are modified in the presence of a gravitational field or in a moving background.

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20

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.

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▪ 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.

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21

Shternin, Petr S., and Dmitrii G. Yakovlev. "Superfluid neutron stars." Physics-Uspekhi 55, no. 9 (September 30, 2012): 935–41. http://dx.doi.org/10.3367/ufne.0182.201209g.1006.

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22

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.

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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.

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23

Piran, Tsvi. "Binary Neutron Stars." Scientific American 272, no. 5 (May 1995): 52–61. http://dx.doi.org/10.1038/scientificamerican0595-52.

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24

Shternin, Petr S., and Dmitrii G. Yakovlev. "Superfluid neutron stars." Uspekhi Fizicheskih Nauk 182, no. 9 (2012): 1006–12. http://dx.doi.org/10.3367/ufnr.0182.201209g.1006.

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25

Bignami, G. F. "Isolated Neutron Stars." Science 271, no. 5254 (March 8, 1996): 1372–73. http://dx.doi.org/10.1126/science.271.5254.1372.

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26

White, N. E. "Accreting Neutron Stars." Symposium - International Astronomical Union 125 (1987): 135–48. http://dx.doi.org/10.1017/s007418090016067x.

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This paper reviews accreting neutron stars in X-ray binaries, with particular emphasis on how variations in magnetic field strength may be responsible for explaining the spectral and temporal properties observed from the various systems. This includes a review of X-ray pulsars in both low and high mass systems, and a discussion of the spectral properties of the low mass X-ray binaries.

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27

Schwarz, D. J., and D. Seidel. "Microlensing neutron stars." Astronomy & Astrophysics 388, no. 2 (May 31, 2002): 483–91. http://dx.doi.org/10.1051/0004-6361:20020530.

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28

Jones, P. B. "Dark neutron stars." Monthly Notices of the Royal Astronomical Society 467, no. 4 (February 23, 2017): 4711–18. http://dx.doi.org/10.1093/mnras/stx459.

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29

Hurley, K. "Active neutron stars." Advances in Space Research 10, no. 2 (January 1990): 179–86. http://dx.doi.org/10.1016/0273-1177(90)90138-p.

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30

Popov, S. "Isolated Neutron Stars." EPJ Web of Conferences 7 (2010): 03002. http://dx.doi.org/10.1051/epjconf/20100703002.

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31

Ögelman, Hakki. "Cooling Neutron Stars." Europhysics News 18, no. 7-8 (1987): 98–101. http://dx.doi.org/10.1051/epn/19871807098.

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32

Franco, Lucia M., Bennett Link, and Richard I. Epstein. "Quaking Neutron Stars." Astrophysical Journal 543, no. 2 (November 10, 2000): 987–94. http://dx.doi.org/10.1086/317121.

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33

Sartore, N., E. Ripamonti, A. Treves, and R. Turolla. "Galactic neutron stars." Astronomy and Astrophysics 510 (February 2010): A23. http://dx.doi.org/10.1051/0004-6361/200912222.

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34

Dexheimer, Veronica. "Properties and Dynamics of Neutron Stars and Proto-Neutron Stars." Universe 8, no. 8 (August 21, 2022): 434. http://dx.doi.org/10.3390/universe8080434.

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35

PÉREZ ROJAS, H., A. PÉREZ MARTÍNEZ, and HERMAN J. MOSQUERA CUESTA. "COLLAPSING NEUTRON STARS DRIVEN BY CRITICAL MAGNETIC FIELDS AND EXPLODING BOSE–EINSTEIN CONDENSATES." International Journal of Modern Physics D 14, no. 11 (November 2005): 1855–60. http://dx.doi.org/10.1142/s0218271805007516.

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A Bose–Einstein condensate of a neutral vector boson bearing an anomalous magnetic moment is suggested as a model for ferromagnetic origin of magnetic fields in neutron stars. The vector particles are assumed to arise from parallel spin-paired neutrons. A negative pressure perpendicular to the external field B is acting on this condensate, which for large densities, compress the system, and may produce a collapse. An upper bound of the magnetic fields observable in neutron stars is given. In the the non-relativistic limit, the analogy with the behavior of exploding Bose–Einstein condensates (BECs) for critical values of the magnetic field is briefly discussed.

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36

Ananthaswamy, Anil. "Quark stars: when neutron stars melt." New Scientist 220, no. 2946 (December 2013): 42–45. http://dx.doi.org/10.1016/s0262-4079(13)62856-0.

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37

Olinto, Angela. "Converting neutron stars into strange stars." Nuclear Physics B - Proceedings Supplements 24, no. 2 (December 1991): 103–9. http://dx.doi.org/10.1016/0920-5632(91)90306-y.

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38

Lu 卢, Xu 旭., and Yi 懿. Xie 谢. "Prediction of Astrometric and Timing Microlensing Events with Pulsars by ATNF Catalog and Gaia DR3." Astrophysical Journal 962, no. 1 (February 1, 2024): 56. http://dx.doi.org/10.3847/1538-4357/ad1929.

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Abstract Determining the mass of neutron stars is crucial for understanding their formation, evolution, and interior structure. Currently, only a few dozen neutron stars have had their masses measured, and most of them belong to binary systems. However, there are a huge number of isolated neutron stars with unknown masses. Microlensing events with neutron stars provide unique opportunities for knowing these compact objects. Astrometric microlensing with a background source lensed by a neutron star might be used to determine the neutron star's mass by measuring the deviation of the motion of the centroid of the images from its unlensed one. We search and predict these recent and future events based on the Australia Telescope National Facility Pulsar Catalog and Gaia DR3. We find 60 candidate astrometric microlensing events caused by neutron stars and the probability distributions of their observables by the Monte Carlo sampling. We also find four candidate “timing microlensing” events with a pulsar lensed by a foreground object that might be detected by timing measurements. While some of these events may be verified by future astrometric missions or pulsar-timing observations, we note that our prediction of these events is significantly restricted by the uncertainties of the available astrometric and timing measurements after assessing and comparing our results with previous works.

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39

Huber, H., F. Weber, M. K. Weigel, and Ch Schaab. "Neutron Star Properties with Relativistic Equations of State." International Journal of Modern Physics E 07, no. 03 (June 1998): 301–39. http://dx.doi.org/10.1142/s0218301398000130.

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We study the properties of neutron stars adopting relativistic equations of state of neutron star matter, calculated in the framework of the relativistic Brueckner–Hartree–Fock approximation for electrically charge neutral neutron star matter in beta–equilibrium. For higher densities more baryons (hyperons etc.) are included by means of the relativistic Hartree– or Hartree–Fock approximation. The special features of the different approximations and compositions are discussed in detail. Besides standard neutron star properties special emphasis is put on the limiting periods of neutron stars, for which the Kepler criterion and gravitation–reaction instabilities are considered. Furthermore the cooling behaviour of neutron stars is investigated, too. For comparison we also give the outcome for some nonrelativistic equations of state.

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40

Østgaard, Erlend. "Compact stars: Neutron stars or quark stars or hybrid stars?" Physics Reports 242, no. 4-6 (July 1994): 313–32. http://dx.doi.org/10.1016/0370-1573(94)90166-x.

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41

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.

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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.

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42

Woosley, S. E. "The Birth of Neutron Stars." Symposium - International Astronomical Union 125 (1987): 255–72. http://dx.doi.org/10.1017/s0074180900160887.

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Presupernova models of massive stars are discussed and their explosion by either the “core bounce” or neutrino energy transport mechanism briefly reviewed. Special consideration is given to those attributes of the stellar evolution and explosion that might influence the properties of the neutron star remnant: its mass, rotation rate, magnetic field, and “kick” velocity.

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43

Zheng, Hua, Jaime Sahagun, and Aldo Bonasera. "Neutron stars and supernova explosions in the framework of Landau's theory." International Journal of Modern Physics E 24, no. 07 (July 2015): 1550059. http://dx.doi.org/10.1142/s0218301315500597.

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In this paper, a general formula of the symmetry energy for many-body interaction is proposed and the commonly used two-body interaction symmetry energy is recovered. Within Landau's theory (Lt), we generalize two equations of state (EoS) CCSδ3 and CCSδ5 to asymmetric nuclear matter. We assume that the density and density difference between protons and neutrons divided by their sum are order parameters. We use different EoS to study neutron stars by solving the TOV equations. We demonstrate that different EoS give different mass and radius relation for neutron stars even when they have exactly the same ground state (gs) properties (E/A, ρ0, K, S, L and K sym ). Furthermore, for one EoS we change K sym and fix all the other gs parameters. We find that for some K sym the EoS becomes unstable at high density even for neutron matter. This suggests that a neutron star (NS) can exist below and above the instability region but in different states: a quark gluon plasma (QGP) at high density and baryonic matter at low density. If the star's central density is in the instability region, then we associate these conditions to the occurrence of supernovae (SN).

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44

Lombardo, U., Caiwan Shen, N. Van Giai, and W. Zuo. "Neutrino mean free path in neutron stars." Nuclear Physics A 722 (July 2003): C532—C537. http://dx.doi.org/10.1016/s0375-9474(03)01422-2.

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45

Strohmayer, T. E. "Oscillations of Rotating Neutron Stars." International Astronomical Union Colloquium 128 (1992): 299–304. http://dx.doi.org/10.1017/s0002731600155386.

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AbstractWe use a perturbation technique to compute the rotational corrections to the non-radial oscillation spectrum of a realistic neutron-star model. We compute, to first order in the rotation rate, the corrections to the normal mode eigenfrequencies and eigenfunctions. We find that l = l0 oscillations are coupled to l = l0 ± 1 oscillations by the Coriolis force. For the toroidal modes, this coupling introduces a non-zero radial component to the velocity field. We have used this result to compute the neutrino damping rates for several corrected toroidal modes. This damping mechanism is inoperative for toroidal modes in a non-rotating star because these modes produce no density nor temperature perturbations. The neutrino damping time can approach the gravitational radiation damping time in rotating neutron stars if the central temperature is high enough, (Tc ≥ 108 K). The rotationally induced coupling of spheroidal oscillations to toroidal modes can also produce significant displacements at the stellar surface. This may have interesting implications for channeling energy, e.g., that associated with a glitch, to the surface of the star. Perhaps this might produce observable effects in the pulsar emission process or a γ-ray burst event.

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46

Potekhin, A. Y., A. I. Chugunov, and G. Chabrier. "Thermal evolution and quiescent emission of transiently accreting neutron stars." Astronomy & Astrophysics 629 (September 2019): A88. http://dx.doi.org/10.1051/0004-6361/201936003.

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Aims. We study the long-term thermal evolution of neutron stars in soft X-ray transients (SXTs), taking the deep crustal heating into account consistently with the changes of the composition of the crust. We collect observational estimates of average accretion rates and thermal luminosities of such neutron stars and compare the theory with observations. Methods. We performed simulations of thermal evolution of accreting neutron stars, considering the gradual replacement of the original nonaccreted crust by the reprocessed accreted matter, the neutrino and photon energy losses, and the deep crustal heating due to nuclear reactions in the accreted crust. We also tested and compared results for different modern theoretical models. We updated a compilation of the observational estimates of the thermal luminosities in quiescence and average accretion rates in the SXTs and compared the observational estimates with the theoretical results. Results. The long-term thermal evolution of transiently accreting neutron stars is nonmonotonic. The quasi-equilibrium temperature in quiescence reaches a minimum and then increases toward the final steady state. The quasi-equilibrium thermal luminosity of a neutron star in an SXT can be substantially lower at the minimum than in the final state. This enlarges the range of possibilities for theoretical interpretation of observations of such neutron stars. The updates of the theory and observations leave the previous conclusions unchanged, namely that the direct Urca process operates in relatively cold neutron stars and that an accreted heat-blanketing envelope is likely present in relatively hot neutron stars in the SXTs in quiescence. The results of the comparison of theory with observations favor suppression of the triplet pairing type of nucleon superfluidity in the neutron-star matter.

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47

MAGIERSKI, PIOTR, AUREL BULGAC, and PAUL-HENRI HEENEN. "NEUTRON STARS AND THE FERMIONIC CASIMIR EFFECT." International Journal of Modern Physics A 17, no. 06n07 (March 20, 2002): 1059–64. http://dx.doi.org/10.1142/s0217751x02010510.

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The inner crust of neutron stars consists of nuclei of various shapes immersed in a neutron gas and stabilized by the Coulomb interaction in the form of a crystal lattice. The scattering of neutrons on nuclear inhomegeneities leads to the quantum correction to the total energy of the system. This correction resemble the Casimir energy and turn out to have a large influence on the structure of the crust.

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48

Ruderman, M. "Neutron Star Powered Accelerators." Symposium - International Astronomical Union 195 (2000): 463–71. http://dx.doi.org/10.1017/s0074180900163508.

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Neutron stars can be the underlying source of energetic particle acceleration in several ways. The huge gravitational-collapse energy released in their birth, or the violent fusion at the end of the life of a neutron-star binary, is the energy source for an accelerator in the surrounding medium far from the star. This would be the case for: (a) cosmic rays from supernova explosions with neutron-star remnants; (b) energetic radiation from “plerions” around young neutron stars (e.g., the Crab Nebula, see Pacini 2000); and (c) “afterglow” and γ-rays of cosmic Gamma-Ray Burst (GRB) sources with possible neutron-star central engines. Particles can also be energetically accelerated if a neutron star's gravitational pull sustains an accretion disk fed by a companion. Examples are accretion-powered X-ray pulsars and low-mass X-ray binaries. A third family of “neutron-star powered” accelerators consists of those which do not depend on the surrounding environment. These are the accelerators which must exist in the magnetospheres of many solitary, spinning-down, magnetized neutron stars (“spinsters”) when they are observed as radio pulsars or γ-ray pulsars. (There are probably ~ 103 dead radio pulsars for each one in our Galaxy that is still active; the ratio for γ-ray pulsars may well exceed 105.)

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Hollowell, David, and Icko Iben. "Nucleosynthesis and Mixing in Low- and Intermediate-Mass AGB Stars." International Astronomical Union Colloquium 108 (1988): 38–43. http://dx.doi.org/10.1017/s0252921100093374.

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AbstractThe existence of carbon stars brighter than Mbol=-4 can be understood in terms of dredge up in thermally pulsing asymptotic giant branch (AGB) stars. As a low- or intermediate-mass star evolves on the AGB, the large fluxes engendered in a helium shell flash cause the base of the convective envelope to extend into the radiative, carbon-rich region, and transport nucleosynthesis products to the stellar surface. Numerical models indicate that AGB stars with sufficiently massive stellar envelopes can become carbon stars via this standard dredge-up mechanism. AGB stars with less massive stellar envelopes can become carbon stars when carbon recombines in the cool, carbon-rich region below the convective envelope.Neutron capture occurs on iron-seed nuclei during a shell flash, and the products of this nucleosynthesis are also carried to the stellar surface. The conversion of 22Ne into 25Mg can initiate neutron capture nucleosynthesis in largecore mass AGB stars, but only if these stars can survive their large mass loss rates. The current estimates of nuclear reaction rates do not allow for appreciable neutron capture nucleosynthesis via the 22Ne source in lower mass AGB stars. The carbon recombination that induces dredge up in AGB stars of small envelope mass, however, also induces mixing of 1H and 12C in such a way that ultimately a 13C neutron source is activated in these stars. The 13C source can provide an abundant supply of neutrons for the nucleosynthesis of both light and heavy elements. While the existence of neutron-nucleosynthesis products in AGB stellar atmospheres can be understood qualitatively in terms of an active neutron source, the combination of nuclear reaction theory and evolutionary models has yet to provide quantitative agreement with stellar observations.

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Alford, Mark, Matt Braby, Mark Paris, and Sanjay Reddy. "Hybrid Stars that Masquerade as Neutron Stars." Astrophysical Journal 629, no. 2 (August 20, 2005): 969–78. http://dx.doi.org/10.1086/430902.

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