Axion effects on quark matter and quark-matter cores in massive hybrid stars

Summary

The study explores the effects of axions on quark matter and quark-matter cores in massive hybrid stars using a three-flavor Nambu-Jona-Lasinio model. The results show that axions decrease the baryon chemical potential of the first-order phase transition, leading to an increase in normalized pressure and stiffening of the quark matter equation of state.

Highlights

• Axions decrease the baryon chemical potential of the first-order phase transition in quark matter.
• The equation of state for quark matter becomes stiffer due to the axion effect.
• The axion field shifts the onset of the hadron-quark mixed phase to lower densities.
• The maximum mass and radius of hybrid stars slightly decrease with increasing axion field.
• The radius and mass of the quark-matter core in hybrid stars significantly increase with the axion field.
• The speed of sound and polytropic index in the pure quark phase exceed the conformal limits.
• The axion effect on the equation of state of hybrid star matter is mostly independent of density or energy density.

Key Insights

• The study suggests that axions can have a significant impact on the properties of quark matter and quark-matter cores in massive hybrid stars, leading to a stiffer equation of state and increased radius and mass of the quark-matter core.
• The results indicate that the axion field can shift the onset of the hadron-quark mixed phase to lower densities, resulting in a slight decrease in the maximum mass and radius of hybrid stars.
• The study finds that the speed of sound and polytropic index in the pure quark phase exceed the conformal limits, indicating that the axion effect can lead to a more complex and interacting system.
• The results suggest that the axion effect on the equation of state of hybrid star matter is mostly independent of density or energy density, indicating that the axion field has a universal impact on the properties of quark matter.
• The study highlights the importance of considering the effects of axions on quark matter and quark-matter cores in massive hybrid stars, as it can provide insights into the behavior of dense and strongly interacting matter.
• The results have implications for our understanding of the properties of neutron stars and the behavior of dense and strongly interacting matter in extreme environments.
• The study demonstrates the potential of using astrophysical observations to constrain models of dense and strongly interacting matter, and highlights the importance of continued research into the properties of quark matter and quark-matter cores in massive hybrid stars.

Mindmap

Citation

Liu, H., Liu, Y.-H., Yang, Y.-H., Ju, M., Wu, X.-H., Liu, H.-M., & Chu, P.-C. (2024). Axion effects on quark matter and quark-matter cores in massive hybrid stars (Version 1). arXiv. https://doi.org/10.48550/ARXIV.2412.17624