# Fully general-relativistic simulations of isolated and binary strange quark stars

**Authors:** Zhenyu Zhu, Luciano Rezzolla  
**arXiv:** [2102.07721](https://arxiv.org/abs/2102.07721)  
**Date:** 2021-02-15  
**Summary page:** https://www.summarizepaper.com/en/paper/2102.07721v1/

## Key points

- Strange quark matter (SQM) is investigated as the true ground state of matter
- A novel technique is presented to address challenges in modeling large discontinuities at the surface of quark stars
- General-relativistic simulations are conducted to study merging binaries of quark stars and hadronic stars
- Important differences are identified between these two types of binary systems, including suppressed dynamical mass loss in quark-star binaries
- Quasi-universal relations between merger and post-merger frequencies exist for both types of binaries when expressed in terms of tidal deformability, but not average stellar compactness
- Differences in velocity and entropy distributions for ejected matter from quark-stars compared to hadronic-stars are observed
- Implications for electromagnetic counterparts and nucleosynthetic yields require further investigation into accurate models for evaporation processes

## Summary

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In this study, the authors investigate the hypothesis that strange quark matter (SQM) is the true ground state of matter. Previous research has explored binary systems of quark stars, but challenges arise in modeling large discontinuities at their surface. To address this issue, the authors present a novel technique where the equation of state (EOS) is rescaled to produce a smooth change in specific enthalpy across a thin crust. The introduction of this crust is validated by considering oscillation properties of isolated quark stars and comparing them to perturbative predictions. Using this new method, fully general-relativistic simulations are conducted to study merging binaries of both quark stars and hadronic stars with similar mass and tidal deformability. Several important differences are identified between these two types of binary systems, including suppressed dynamical mass loss in quark-star binaries compared to hadronic-star binaries. Additionally, while both exhibit quasi-universal relations between merger and post-merger frequencies when expressed in terms of tidal deformability, this relationship does not hold when expressed in terms of average stellar compactness. This highlights the challenge in distinguishing between these two types without information on stellar radius. Furthermore, there are differences in velocity and entropy distributions for ejected matter from quark-stars compared to hadronic-stars due to their colder and more self-bound nature. The implications for electromagnetic counterparts and nucleosynthetic yields remain unclear and call for further investigation into accurate models for evaporation processes. Overall, this study provides valuable insights into binary systems of strange quark matter and highlights its unique characteristics compared to hadronic counterparts.