Slowly rotating anisotropic neutron stars in general relativity and scalar–tensor theory

By Hector O. Silva, C. F. Macedo, Emanuele Berti, L. Crispino. 2014

173 citations recorded by the source corpus.

Some models (such as the Skyrme model, a low-energy effective field theory for quantum chromodynamics) suggest that the high-density matter prevailing in neutron star (NS) interiors may be significantly anisotropic. Anisotropy is known to affect the bulk properties of nonrotating NSs in general relativity (GR). In this paper we study the effects of anisotropy on slowly rotating stars in GR. We also consider one of the most popular extensions of Einstein’s theory, namely scalar–tensor theories allowing for spontaneous scalarization (a phase transition similar to spontaneous magnetization in ferromagnetic materials). Anisotropy affects the moment of inertia of NSs (a quantity that could potentially be measured in binary pulsar systems) in both theories. We find that the effects of scalarization increase (decrease) when the tangential pressure is bigger (smaller) than the radial pressure, and we present a simple criterion to determine the onset of scalarization by linearizing the scalar-field equation. Our calculations suggest that binary pulsar observations may constrain the degree of anisotropy or even, more optimistically, provide evidence for anisotropy in NS cores.

Subfields: Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/9a1c286316e54e255b4be4122665dcc714bc81a5

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Paolo Pani
2. V. Cardoso
3. Kent Yagi
4. N. Yunes
5. Diego Rubiera-García
6. Aneta Wojnar
7. G. Olmo
8. Joseph Keir

In Oceanography

1. N. Yunes
2. Diego Rubiera-García
3. V. Cardoso
4. Paolo Pani
5. G. Olmo
6. Aneta Wojnar
7. Kent Yagi

Citations in the corpus

• Approximate Universal Relations for Neutron Stars and Quark Stars (2016, methodology): “One way to construct anisotropic stars is to use the matter stress-energy tensor [222, 224]:”
• Tests for the existence of black holes through gravitational wave echoes (2017, background): “Anisotropic stars ClePhOs 7 X X X [59–61] [62,63] [35,61,64] [35,64]”
• Slowly decaying waves on spherically symmetric spacetimes and ultracompact neutron stars (2014, background): “[29]), in the sense of  R M 3 , and anisotropic neutron stars may become ultracompact much more easily [30].”
• Stellar structure models in modified theories of gravity: Lessons and challenges (2019, background): “Assuming again a dependence (108) and focusing on the APR EOS for the radial pressure Pr, and the Horvat (97), and Bowers-Liang (98) EOS for the anisotropy σ ≡ Pr − P⊥, with the constraints stressed in those equations, the authors of [366] set standard boundary conditions at the center upon density,”