Ridges in rotating neutron-star properties due to first order phase transitions

Abstract

We identify combinations of observables for rotating neutron stars that can one day bear on the question of whether there can be first order phase transitions in the neutron matter therein. We employ the Hartle-Thorne theory for stationary, rotating neutron stars at conventional angular velocities (in the pulsar and millisecond pulsar ranges) and extract three-dimensional sections of the ellipticity or the dynamical angular momentum as function of the star's mass and angular velocity. An eventual first order phase transition in the equation of state (EoS) leaves a clear ridge (nonanalyticity) in these observables, akin to the sudden kink in popular mass-radius diagrams for static stars. Finally, we observe that static neutron stars in General Relativity (GR) will fail to be compact enough for the light ring's position at r=3M to be outside the star, except for the most extreme equations of state. The outer light ring of a rotating star might however be formed unless the EoS softens too much, and its eventual detection can then be used to constrain the EoS (or the gravity theory).

17 pages, 26 plots, thoroughly revised following refereeing

References in corpus (17)

• A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation
• Science with the Einstein Telescope: a comparison of different designs
• A NICER view of PSR J0030+0451: Implications for the dense matter equation of state
• Review of the Advanced LIGO gravitational wave observatories leading to observing run four
• The Photon Ring in M87*
• Dense matter equation of state of a massive neutron star with anti-kaon condensation
• Consequences of a strong phase transition in the dense matter equation of state for the rotational evolution of neutron stars
• Limits on hierarchical black hole mergers from the most negative ${\chi }_{\mathrm{eff}}$ systems
• Measuring neutron-star ellipticity with measurements of the stochastic gravitational-wave background
• Effects of the quark-hadron phase transition on highly magnetized neutron stars
• How narrow is the M87* ring? II. A new geometric model
• Rapidly rotating neutron stars in $f(R,T)$ gravity
• Quark Deconfinement in Rotating Neutron Stars
• Cooling of Neutron Stars admixed with Light Dark Matter: a case study
• Slowly rotating Tolman VII solution
• Universal relations for quasinormal modes of neutron stars in $R^2$ gravity
• Phase diagram of neutron star quark matter in nonlocal chiral models

Cited by in corpus (6)

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• Testing gravity with the latent heat of neutron star matter