Neutron star matter equation of state including d*-hexaquark degrees of freedom

Abstract

We present an extension of a previous work where, assuming a simple free bosonic gas supplemented with a relativistic mean field model to describe the pure nucleonic part of the EoS, we studied the consequences that the first non-trivial hexaquark d(2380) could have on the properties of neutron stars. Compared to that exploratory work we employ a standard non-linear Walecka model including additional terms that describe the interaction of the d(2380) di-baryon with the other particles of the system through the exchange of sigma and rho meson fields. Our results have show that the presence of the d(2380) leads to maximum masses compatible with the recent observations of 2M millisecond pulsars if the interaction of the d(2380) is slightly repulsive or the d(2380) does not interact at all. An attractive interaction makes the equation of state too soft to be able to support a 2M neutron star whereas an extremely repulsive one induces the collapse of the neutron star into a black hole as soon as the d(2380) appears.

Metadata

Authors/Creators:

Mantziris, A.
Pastore, A. https://orcid.org/0000-0003-3354-6432
Vidaña, I.
Watts, D. P. https://orcid.org/0000-0003-4758-9599
Bashkanov, M. https://orcid.org/0000-0001-9822-9433
Romero, A. M.

Funding Information: Acknowledgements. This work was partially supported by the STFC Grants No. ST/M006433/1 and ST/P003885/1, ST/L00478X/1 and by the COST Action CA16214 “PHAROS: The multimessenger physics and astrophysics of neutron stars”. © ESO 2020. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

Keywords:

Dense matter, Equation of state, Stars: neutron

Dates: