Stiff phases in strongly coupled gauge theories with holographic duals

Abstract

According to common lore, Equations of State of field theories with gravity duals tend to be soft, with speeds of sound either below or around the conformal value of $v_s=1/\sqrt{3}$. This has important consequences in particular for the physics of compact stars, where the detection of two solar mass neutron stars has been shown to require very stiff equations of state. In this paper, we show that no speed limit exists for holographic models at finite density, explicitly constructing examples where the speed of sound becomes arbitrarily close to that of light. This opens up the possibility of building hybrid stars that contain quark matter obeying a holographic equation of state in their cores.

22 pages+appendices, 12 figures

References in corpus (10)

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• Towards Understanding Astrophysical Effects of Nuclear Symmetry Energy
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• Impact of large-mass constraints on the properties of neutron stars
• Is entanglement a probe of confinement?
• Remarks on nuclear matter: how an ${\omega }_0$ condensate can spike the speed of sound, and a model of $Z(3)$ baryons
• Holographic approach to compact stars and their binary mergers
• Holographic approach to transport in dense QCD matter
• Gravitational waves from a holographic phase transition
• Insights on the peak in the speed of sound of ultradense matter
• Neutron stars and phase diagram in a hard-wall AdS/QCD model
• Gravity dual of a multilayer system
• Quantum information probes of charge fractionalization in large-$N$ gauge theories
• Aspects of univalence in holographic axion models
• Scattering length from holographic duality
• Flavored anisotropic black holes
• Insensitivity of the complexity rate of change to the conformal anomaly and Lloyd's bound as a possible renormalization condition
• Effects of a Brueckner-Hartree-Fock-corrected effective mass on speed of sound, conformality, and observables of dark matter-admixed neutron stars
• Exceeding the conformal limit inside rotating neutron stars: Implications to modified theories of gravity