Universal I-Q relations for rapidly rotating neutron and strange stars in scalar-tensor theories

Abstract

We study how rapid rotation influences the relation between the normalized moment of inertia $\bar{I}$ and quadrupole moment $\bar{Q}$ for scalarized neutron stars. The questions one has to answer are whether the EOS universality is preserved in this regime and what are the deviations from general relativity. Our results show that the $\bar{I}-\bar{Q}$ relation is nearly EOS independent for scalarized rapidly rotating stars, but the differences with pure Einstein's theory increase compared to the slowly rotating case. In general, smaller negative values of the scalar field coupling parameters $\beta$ lead to larger deviations, but these deviations are below the expected accuracy of the future astrophysical observations if one considers values of $\beta$ in agreement with the current observational constraint. An important remark is that although the normalized $\bar{I}-\bar{Q}$ relation is quite similar for scalar-tensor theories and general relativity, the unnormalized moment of inertia and quadrupole moment can be very different in the two theories. This demonstrates that although the $\bar{I}-\bar{Q}$ relations are potentially very useful for some purposes, they might not serve us well when trying to distinguish between different theories of gravity.

8 pages, 3 figures

References in corpus (9)

• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• Further explorations of Skyrme-Hartree-Fock-Bogoliubov mass formulas. XII: Stiffness and stability of neutron-star matter
• The relativistic pulsar-white dwarf binary PSR J1738+0333 II. The most stringent test of scalar-tensor gravity
• Constraints on neutron star radii based on chiral effective field theory interactions
• I-Love-Q, Spontaneously: Slowly Rotating Neutron Stars in Scalar-Tensor Theories
• Quadrupole Moments of Rapidly Rotating Compact Objects in Dilatonic Einstein-Gauss-Bonnet Theory
• Universality of the Acceleration Due to Gravity on the Surface of a Rapidly Rotating Neutron Star
• Why I-Love-Q

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