An Ultra-Low-Mass and Small-Radius Compact Object in 4u 1746-37?

Li, Zhaosheng; Qu, Zhijie; Chen, Li; Guo, Y.; Qu, J. L.; Xu, R. X.

doi:10.1088/0004-637x/798/1/56

Cited by 33 publications

(36 citation statements)

References 58 publications

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“…In this work we apply the UG model for NSs for the ultralow, moderate, and ultrahigh mass regimes, i.e., for the following NSs: 4U1746-37 [38], M13 [39], and J0348+0432 [40], respectively. Table I [39], and J0348+0432 [40].…”

Section: Resultsmentioning

confidence: 99%

“…(A8) into Eq. (A6) and using straightforward mathematics, we obtain The allowed region for the UG parameters α and R * for (a) 4U1746-37 [38], (b) M13 [39], and (c) J0348+0432 [40] with the polytropic index n = 0.68. …”

Section: Resultsmentioning

confidence: 99%

“…In Sec. IV, we shall present the numerical results for 4U1746-37 [38], M13 [39], and J0348+0432 [40], for NSs in the ultralow, moderate, and ultrahigh mass regimes, respectively.…”

Section: The Ug Hydrostatic Equilibrium Equationmentioning

confidence: 99%

“…We also aim to investigate the astronomical constrains on the UG parameters, i.e., the scaling dimension and the characteristic length, with respect to observational data of NSs. Based on the observational data of the selected pulsars, i.e., 4U1746-37 [38], M13 [39], and J0348+0432 [40], at the ultralow, moderate, and ultrahigh mass regimes, respectively, we can get bounds on the UG parameters. We shall analytically show how the UG I-Love-Q relations deviate from the universal I-Love-Q relations for slowly rotating NSs with uniform density.…”

Section: Introductionmentioning

confidence: 99%

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Neutron stars, ungravity, and the I-Love-Q relations

Mariji

Bertolami

2017

Phys. Rev. D

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We study neutron stars (NSs) in an ungravity (UG) inspired model. We examine the UG effects on the static properties of the selected NSs, in different mass and radius regimes, i.e., ultralow, moderate, and ultrahigh NSs, using a polytropic equation of state approach. Based on the observational data, we obtain bounds on the characteristic length and scaling dimension of the UG model. Furthermore, we obtain dynamic properties, such as inertial moment (I), Love number (Love), and quadrupole moment (Q) of a slowly rotating NS in the presence of the exterior gravity and ungravity fields. The UG model is also examined with respect to the I-Love-Q universal relation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…In Sec. IV, we shall present the numerical results for 4U1746-37 [38], M13 [39], and J0348+0432 [40], for NSs in the ultralow, moderate, and ultrahigh mass regimes, respectively.…”

Section: The Ug Hydrostatic Equilibrium Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Neutron stars, ungravity, and the I-Love-Q relations

Mariji

Bertolami

2017

Phys. Rev. D

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“…In addition to the maximum mass, the different mass-radius relations would also be helpful to distinguish between strangeon star and neutron star models. In fact, the photospheric radius expansion bursts of 4U 1746-37 show that the compact object could be a low mass strangeon star candidate [18]. A strangeon star is globally solid, whose spin would not be limited by the r-mode instability and gravitational wave radiation (especially for low-mass strangeon star) [19], pulsars with rotation periods shorter than 1.3 millisecond and even a sub-millisecond spin could exist in principle.…”

Section: Strangeon Star Identificationmentioning

confidence: 99%

Strangeon Stars

Lu¹,

Xu²

2018

Proceedings of the Workshop on Quarks and Compact Stars 2017 (QCS2017)

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Stable micro-nucleus is 2-flavored (u and d), whereas stable macro-nucleus could be 3-flavored (u, d and s) if the light flavor symmetry restores there. Nucleons are the constituent of a nucleus, while strangeons are named as the constituent of 3-flavored baryonic matter. Gravity-compressed baryonic object created after core-collapse supernova could be strangeon star if the energy scale (∼ 0.5 GeV) cannot be high enough for quark deconfinement and if there occurs 3-flavor symmetry restoration. Strangeon stars are explained here, including their formation and manifestation/identification. Much work, coupled with effective micro-model of strangeon matter, is needed to take advantage of the unique opportunities advanced facilities will provide. KEYWORDS: pulsar: general, dense matter, equation of stateAlthough the state equation of dense matter around nuclear density is a great challenge for physicists, it is usually a thought that strangeness could be relevant to the solution. As noted in the QC-S2014 proceedings [1], such kind of strange matter is conjectured to be strangeon matter, being manifested in the form of compact stars, cosmic rays, and even dark matter. In this contribution, we are focusing on strangeon star, which is a key ingredient of strangeon matter in astrophysics.It is half a century since the first pulsar was discovered, but the real nature of pulsar remains one of the most puzzling problems both in physics and in astronomy. Pulsars are always thought to be neutron stars, but the issue of their real structure is still controversial. Different observations (e.g., the spin period, the measurements of mass and radius) show that the typical density of pulsar-like compact stars could be only a few nuclear density, and the separation between quarks is ∼ 0.5 fm and hence the energy scale is order of ∼ 0.5 GeV according to Heisenberg's uncertainty relation. The pulsar structure is then a problem of non-perturbative QCD (quantum chromo-dynamics), an unsolved issue for fundamental strong interaction at low energy regime ( 1 GeV). Similar to the issue of turbulence, the strong interaction physics at low-energy is still challenging though QCD is mathematically well-defined. In fact, both of "Navier-Stokes Equation" and "Yang-Mills and Mass Gap" are prize problems named by the Clay Mathematical Institute. Hitherto now, no one can derive pulsar structure from ab-initio calculations, nonetheless astrophysicists could speculate phenomenologically.In Fig. 1, we summarize pulsar inner structures (i.e., models) speculators suggest. All of the pulsar structure models fell into four categories: hadron star, quark star, hybrid/mixed star and strangeon star, as are shown in Fig. 1. In the hadron star model, quarks are confined in hadrons, and the hadron liquid is the dominated part of the star. Hadron stars are bounded by gravity, and they must have crusts composed of ions and electrons. A hadron star is called a neutron star if only the nucleon (proton and neutron) degree of freedom is introduced. Conversely, a quark...

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4U 1746–37: An ultra‐low‐mass compact star candidate

2015

Astron Nachr

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Key words dense matter -equation of state -stars: neutron -X-rays: bursts -X-rays: binaries the Rossi X-ray Timing Explorer observed three photospheric radius expansion bursts in 4U 1746-37, all with low touchdown fluxes. We discuss the possibility of a low-mass neutron star in 4U 1746-37 if the touchdown flux corresponds to its Eddington limit. 4U 1746-37 is a dipping binary system which has a high inclination angle. Two geometric effects, the reflection of the far side accretion disc and the obscuration of the near side accretion disc have also been included. We apply a Monte-Carlo simulation, with typical values of hydrogen mass fraction and color correction factor, to constrain the mass and radius of the neutron star in 4U 1746-37. We found that the mass of 4U 1746-37 is 0.41 +0.70 −0.30 M at 99.7 % confidence which is an ultra-low-mass compact star candidate. It could be reproduced by a self-bound compact star, i.e., quark star or quark-cluster star, from an ccretion-induced collapse process.

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An Ultra-Low-Mass and Small-Radius Compact Object in 4u 1746-37?

Cited by 33 publications

References 58 publications

Neutron stars, ungravity, and the I-Love-Q relations

Neutron stars, ungravity, and the I-Love-Q relations

Strangeon Stars

4U 1746–37: An ultra‐low‐mass compact star candidate

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