Identifying Quark Matter in Hybrid Stars through Relativistic Tidal Deformations

Bryen Irving,Thomas Klähn,Wei Wei,Marc Salinas,Prashanth Jaikumar

doi:10.3390/universe5090193

Abstract

We study a specific model of neutron star matter that supports a phase transition to quark matter at high density and examine parameter ranges for consistency with the mass-weighted tidal deformability of Λ ˜ = 300 − 230 + 420 for a mass ratio of q ∈ [ 0.73 , 1.0 ] , as inferred from observations of gravitational waves from the binary neutron star merger event GW170817. By using this observation to restrict the parameter space for the equation of state (EoS) model used throughout this study, we aim to assess the possibility of a potential solution to the masquerade and flavor camouflage problems for hybrid EoS models. Assuming the two stars have the same EoS, in which the Dirac-Brueckner-Hartree Fock (DBHF) nuclear model transitions to the vBag quark model, we see if the parameter space of these hybrid model stars are restricted due to the adherence to the reported Λ 1.4 ∈ 70 , 580 and M m a x ∈ [ 2.01 , 2.16 ] M ⊙ constraints. Upon completion, we find that, while the parameter space for our model does get restricted, it does not ultimately resolve the masquerade and flavor camouflage problems.

Highlights

Understanding the equation of state of strongly interacting matter under the extreme conditions in compact stars is a key problem of interest in astrophysics [1,2]
A common approach to understanding the type of star configurations produced by a given equation of state (EoS) model is to analyze the mass-radii relation of the set
The parameters established in the vBag model control the type of curves that result after the transition from hadronic to quark matter occurs

Summary

Introduction

Understanding the equation of state of strongly interacting matter under the extreme conditions in compact stars is a key problem of interest in astrophysics [1,2]. One of the most pressing issues revolves around understanding models that experience a phase transition from hadronic to deconfined quark matter at densities several times that of nuclear saturation. While modern observational techniques have allowed for constraints to the mass–radius relations of these stars to be generated, the so-called “masquerade” [3]. “flavor camouflage” [4] problems still persist. As it stands, based on current observational techniques, a hybrid star with quark matter in its interior is indistinguishable from that of an ordinary Neutron Star (NS)—even more so if mixed phases exist. When considering phase transitions from nuclear to two-flavor (2f) or three-flavor (3f), matter signatures in the mass–radius relations become effectively camouflaged when compared to their purely nuclear counterparts. It becomes apparent that additional methods are needed to further understand these hybrid models

Objectives

Results

Conclusion