Heavy Magnetic Neutron Stars

Rather, Ishfaq A.; Rahaman, Usuf; Dexheimer, V.; Usmani, A. A.; Patra, S. K.

doi:10.3847/1538-4357/ac09f7

Cited by 30 publications

(13 citation statements)

References 160 publications

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“…Regarding the effect of the strong MF, we find that not always the magnetar models have a higher maximum mass than the low MF models, unlike other works (Rabhi et al 2009;Mariani et al 2019;Thapa et al 2020;Rather et al 2021); in our model, Sets 1 and 2 show slightly higher maximum masses for magnetars, but for Set 3 3 for details).…”

Section: Results For Stellar Structure and Stabilitycontrasting

confidence: 66%

Oscillating magnetised hybrid stars under the magnifying glass of multi-messenger observations

Mariani,

Tonetto,

Rodríguez

et al. 2022

Preprint

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We model neutron stars as magnetised hybrid stars with an abrupt hadron-quark phase transition in their cores, taking into account current constraints from nuclear experiments and multi-messenger observations. We include magnetic field effects considering the Landau level quantisation of charged particles and the anomalous magnetic moment of neutral particles. We construct the magnetised hybrid equation of state, and we compute the particle population, the matter magnetisation and the transverse and parallel pressure components. We integrate the stable stellar models, considering the dynamical stability for rapid or slow hadron-quark phase conversion. Finally, we calculate the frequencies and damping times of the fundamental and 𝑔 non-radial oscillation modes. The latter, a key mode to learn about phase transitions in compact objects, is only obtained for stars with slow conversions. For low magnetic fields, we find that one of the objects of the GW170817 binary system might be a hybrid star belonging to the slow extended stability branch. For magnetars, we find that a stronger magnetic field always softens the hadronic equation of state. Besides, only for some parameter combinations a stronger magnetic field implies a higher hybrid star maximum mass. Contrary to previous results, the incorporation of anomalous magnetic moment does not affect the studied astrophysical quantities. We discuss possible imprints of the microphysics of the equation of state that could be tested observationally in the future, and that might help infer the nature of dense matter and hybrid stars.

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Section: Results For Stellar Structure and Stabilitycontrasting

confidence: 66%

Oscillating magnetised hybrid stars under the magnifying glass of multi-messenger observations

Mariani,

Tonetto,

Rodríguez

et al. 2022

Preprint

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“…In this sense, the observation of NSs of a mass higher than 2 M , the most massive NS observed to date, with a mass of ∼2.28 M (Kandel & Romani 2020) or a 2.08 M NS (Fonseca et al 2021), rejected the validity of many proposed EoS; furthermore the first observation of gravitational waves (GWs) emitted by a binary NS merger (Abbott et al 2017) set additional limits on their stiffness (Abbott et al 2018;Bauswein 2019). Moreover, if the low-mass component of the recent binary coalescence event GW190814 (Abbott et al 2020a) is interpreted as a NS, it would set extremely stringent limits on the maximum mass that a valid EoS must be able to reach (Kanakis-Pegios et al 2021;Godzieba et al 2021;Lim et al 2021;Rather et al 2021;Bombaci et al 2021). On the other hand, the recent results of the NICER telescope (Pang et al 2021;Zhang & Li 2021) allowed tighter limits to be set on the possible EoS of NSs by constraining their radius.…”

Section: Introductionmentioning

confidence: 99%

Quasi-universality of the magnetic deformation of neutron stars in general relativity and beyond

Soldateschi

Bucciantini

Zanna

2021

A&A

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Neutron stars are known to host extremely powerful magnetic fields. Among its effects, one of the consequences of harbouring such fields is the deformation of the neutron star structure, leading, together with rotation, to the emission of continuous gravitational waves. On the one hand, the details of their internal magnetic fields are mostly unknown. Likewise, their internal structure, encoded by the equation of state, is highly uncertain. Here, we present a study of axisymmetric models of isolated magnetised neutron stars for various realistic equations of state considered viable by observations and nuclear physics constraints. We show that it is possible to find simple relations between the magnetic deformation of a neutron star, its Komar mass, and its circumferential radius in the case of purely poloidal and purely toroidal magnetic configurations that satisfy the criterion for equilibrium in the Bernoulli formalism. Such relations are quasi-universal, meaning that they are mostly independent from the equation of state of the neutron star. Thanks to their formulation in terms of potentially observable quantities, as we discuss, our results could help to constrain the magnetic properties of the neutron star interior and to better assess the detectability of continuous gravitational waves by isolated neutron stars, without knowing their equation of state. Our results are derived both in general relativity and in scalar-tensor theories (one of the most promising extensions of general relativity), in this case by also considering the scalar charge. We show that even in this case, general relations that account for deviations from general relativity still hold, which could potentially be used to set constraints on the gravitational theory.

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“…This approximation is taken for the simplicity of the calculations. It can be considered equivalent to the density/chemical potential dependent magnetic field profiles where the central field is quite low [95,114]. In such circumstances, the EoS does not deviate much from the field-free case, and the magnetic field almost becomes constant for most parts of NS [95,114].…”

Section: Unified Eos and Neutron Star Observablesmentioning

confidence: 99%

Pasta properties of the neutron star within effective relativistic mean-field model

et al. 2022

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Even though the crystallize nature of the neutron star crust plays a pivotal role in describing various fascinating astrophysical observations, its microscopic structure is not fully understood in the presence of a colossal magnetic field. In the present work, we study the crustal properties of a neutron star within an effective relativistic mean field framework in the presence of magnetic field strength ∼ 10 17 G. We calculate the equilibrium composition of the outer crust by minimizing the Gibbs free energy using the most recent atomic mass evaluations. The magnetic field significantly affects the equation of state (EoS) and the properties of the outer crust, such as neutron drip density, pressure, and melting temperature. For the inner crust, we use the compressible liquid drop model for the first time to study the crustal properties in a magnetic environment. The inner crust properties, such as mass and charge number distribution, isospin asymmetry, cluster density, etc., show typical quantum oscillations (De Haas-van Alphen effect) sensitive to the magnetic field's strength. The densitydependent symmetry energy influences the magnetic inner crust like the field-free case. We study the probable modifications in the pasta structures and it is observed that their mass and thickness changes by ∼ 10 − 15% depending upon the magnetic field strength. The fundamental torsional oscillation mode frequency is investigated for the magnetized crust in the context of quasiperiodic oscillations (QPO) in soft gamma repeaters. The magnetic field strengths considered in this work influences only the EoS of outer and shallow regions of the inner crust, which results in no significant change in global neutron star properties. However, the outer crust mass and its moment of inertia increase considerably with increase in magnetic field strength.

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Heavy Magnetic Neutron Stars

Cited by 30 publications

References 160 publications

Oscillating magnetised hybrid stars under the magnifying glass of multi-messenger observations

Oscillating magnetised hybrid stars under the magnifying glass of multi-messenger observations

Quasi-universality of the magnetic deformation of neutron stars in general relativity and beyond

Pasta properties of the neutron star within effective relativistic mean-field model

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