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Multipole moments and universal relations for scalarized neutron stars

Pappas, George; Doneva, Daniela D.; Sotiriou, Thomas P.; Yazadjiev, Stoytcho S.; Kokkotas, Kostas D.


George Pappas

Daniela D. Doneva

Thomas P. Sotiriou

Stoytcho S. Yazadjiev

Kostas D. Kokkotas


Project Manager


In recent years there has been a surge of interest in what has come to be known as the “universal relations” between various global properties of neutron stars. These universal relations are equation of state independent relations between quantities such as the moment of inertia I, the tidal deformability or Love number λ, and the quadrupole Q (I-Love-Q relations), or the relativistic multipole moments (3-hair relations). While I-Love-Q relations have been studied extensively in both general relativity and various alternatives, 3-hair relations have been studied only in general relativity. Recent progress on the definition of the multipole moments of a compact object in the case of scalar-tensor theories allows for the study of 3-hair relations in modified theories of gravity. Specifically, the aim of this work is to study them for scalarized stars in scalar-tensor theories with a massless scalar field that admit spontaneous scalarization. We find that the 3-hair relations between the mass and angular momentum moments that hold in general relativity hold for scalarized stars as well. The scalar moments also exhibit a universal behavior, which is equation of state independent within one specific theory, but differs between different theories. Combining astrophysical observations one can in principle measure the different properties of scalarized neutron star and tell different theories apart.

Journal Article Type Article
Publication Date May 15, 2019
Journal Physical Review D
Print ISSN 2470-0010
Electronic ISSN 2470-0029
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 99
Issue 10
Article Number 104014
Institution Citation Pappas, G., Doneva, D. D., Sotiriou, T. P., Yazadjiev, S. S., & Kokkotas, K. D. (2019). Multipole moments and universal relations for scalarized neutron stars. Physical Review D, 99(10), doi:10.1103/physrevd.99.104014
Keywords Physics and Astronomy (miscellaneous)
Publisher URL
Additional Information Multipole moments and universal relations for scalarized neutron stars,
George Pappas, Daniela D. Doneva, Thomas P. Sotiriou, Stoytcho S. Yazadjiev, and Kostas D. Kokkotas, Phys. Rev. D 99, 104014.


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