Properties of Stable Massive Quark Stars in Holography

TL;DR

This paper uses a holographic model to explore the properties of dense quark stars, suggesting they can be as massive as 2 solar masses with a stiff equation of state, and discusses the presence of quark cores in heavy stars.

Contribution

It introduces a holographic D3/D7 model with phenomenologically adjusted dilaton profile to study stable massive quark stars with potential quark cores.

Findings

The equation of state can support stars up to 2 solar masses.

Weakly first-order transition allows for stable quark cores.

Holographic baryons as wrapped D5-branes are unrealistic in this context.

Abstract

We study a holographic D3/D7 system, whose dilaton profile has been phenomenologically adjusted in the infrared. The model is used to describe a deconfined yet massive quark phase of QCD at finite density, concluding that the equation of state of such a phase can be stiff enough to support exotic dense stars as massive as 2 solar masses. Nucleons are modeled phenomenologically using the Hebeler-et.al EFT baryon phases. For the stiff phenomenological baryon phases the transition to the quark phase is weakly first order allowing for stable quark cores. We also find that holographic baryons, modeled as wrapped D5-branes, provide unrealistic pressures (in the homogeneous approximation) and have to be discarded. We compute the mass vs. radius relation and tidal deformability for these hybrid stars. Contrary to a large number of other holographic models, this holographic model indicates that quark matter could be present at the core of heavy compact stars and may be used to explore the phenomenology of such objects.