Axion effects in the stability of hybrid stars

Understand

We investigate the effects of including strong charge-parity (CP) violating effects through axion fields in the microscopic equation of state of massive hybrid neutron stars.

• We assume that their cores contain deconfined quark matter and include the effects of axions via an effective 't Hooft determinant interaction.
• The hadronic crusts are described using different approaches in order to make our results more general.
• We find that the presence of axions stabilizes massive hybrid neutron stars against gravitational collapse by weakening the deconfinement phase transition and bringing it to lower densities.