Thesis

Magnetized neutron stars

• Call:

  IDPASC Portugal - PHD Programme 2017

• Academic Year:

  2017 / 2018

• Domains:

  Theoretical Particle Physics | Astrophysics

• Supervisor:

  Constança Providência

• Co-Supervisor:

  Orlando Oliveira

• Institution:

  Universidade de Coimbra

• Host Institution:

  CFisUC

• Abstract:

  The sensitivity of the properties of rotating and magnetized neutron stars to a unified crust-core EoS, and calibrated EoS will be investigated. Microphysical nuclear EoS, general relataivity, magnetic (B) fields and rotation will be incorporated to get a state-of-the-art, realistic, neutron star calculations. In addition, the effect of an unified crust-core EoS on gravitational wave radiation emitted by isolated and binary neutron star systems will also be investigated. A fully general relativistic approach will be employed in which we will focus on the global structure properties of uniformly rotating and magnetized NS relevant for astrophysical applications such as mass, polar and equatorial radii, angular velocity, moment of inertia, quadrupole moment and gravitational wave (GW) amplitude. This will be done for a selected sample of EoS with different symmetry energy slopes and a unified inner-crus EoS. Star properties such as the mass and radius will be determined from the integration of the coupled Einstein-Maxwell equations by means of a pseudo-spectral method, taking into consideration the anisotropy of the energy-momentum tensor due to the B-field and also the effects of the centrifugal force induced by rotation in order to obtain both rotating and magnetized stellar models [Bonazzola93,Bocquet95,Franzon15,Franzon16a]. For that purpose, we are going to use the Lorene C++ library for numerical relativity [Lorene]. The already existing codes for a poloidal magnetic field will be generalized to a toroidal magnetic field. Recent calculations indicate that the crust-core transition density could be larger for magnetized stars with B-fields stronger than $10\times 10^{15}$ G in the crust [Fang16]. The effect of the strong B-fields and rotation on the crust thickness of the stars and onset density of the direct Urca will be studied The influence of an unified EoS in GW radiation emitted by fast rotating and magnetized neutron stars will be investigated, and self-consistently relativistic solutions for NS with poloidal and toroidal B-fields will be computed by solving the Einstein-Maxwell field equations. The B-field supplies an anisotropic pressure, leading to the breaking of the spherical symmetry of the star. The quadrupole moment of the mass distribution will be calculated and an estimation of the GW of such objects will be performed in the same spirit as in Refs. [Franzon16,Bonazzola96]. The the GW amplitude of our stellar models will be compared with the sensitivity curves of current ground-based GW interferometers. In particular, the effect of an unified crust-core EoS on gravitational wave radiation emitted by isolated and binary neutron star systems will be investigated.Such a calculation and the models presented in this work will serve in the future as the initial data conditions for simulations of realistic EoS hydrodynamical mergers. Bonazzola93- S. Bonazzola, E. Gourgoulhon, M. Salgado, and J. Marck, Astron. and Astrophys. 278, 421 (1993). Bocquet95- M. Bocquet, S. Bonazzola, E. Gourgoulhon, and J. Novak, Astron. and Astrophys. 301, 757 (1995). Fortin16 - M. Fortin, C. Providencia, A. R. Raduta, F. Gulminelli, J. L. Zdunik, P. Haensel, and M. Bejger, Phys. Rev. C 94, 035804 (2016). lorene- www.lorene.obspm.fr. Fang16 - J. Fang, H. Pais, S. Avancini, and C. Provid\^encia, Phys. Rev. C 94, 062801(R) (2016). Franzon16 - B. Franzon and S. Schramm, Mon. Not. Roy. Astron. Soc. 467, 4484 (2017) Bonazzola96 - S. Bonazzola and E. Gourgoulhon, Astron. Astrophys. 312, 675 (1996).