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

Understand

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.