Download The Constant-Sound-Speed parameterization of the quark matter EoS

The Constant-Sound-Speed parameterization of the quark
matter EoS
Mark. G. Alford1
1
Physics Department, Washington University, St. Louis, MO 63130, USA
At high pressure, nuclear matter will undergo a transition to quark matter, so
sufficiently heavy neutron stars may really be “hybrid stars” with quark matter
cores. Since little is known about the quark matter equation of state, we perform a
model-independent study of the form of the mass-radius relation for hybrid stars,
making only some generic assumptions about the quark matter EoS.
The CSS parameterization of the EoS has three parameters:
(1) at what pressure the nuclear→quark transition occurs;
(2) the energy density discontinuity at the transition;
(3) the quark matter speed of sound c2QM .
Observations of the mass and radius of neutron stars can be characterized,
in a model-independent way, as constraints on the values of these parameters. In
particular, the speed of sound in quark matter is already constrained to c2QM & 1/3.
A
∆ε εtrans
D
B
C
ptrans εtrans
1. Generic conditions for stable hybrid stars.
M. Alford, S. Han, M. Prakash, Phys. Rev. D 88, 083013, 2013. [arXiv:1302.4732].
2. Constraining and applying a generic high-density equation of state.
M. Alford, G. Burgio, S. Han, G. Taranto, D. Zappalà, Phys. Rev. D92, 083002,
2015. [arXiv:1501.07902].
3. The Constant-Sound-Speed parameterization for NJL models of quark matter in
hybrid stars. I. Ranea-Sandoval, S. Han, M. Orsaria, G. Contrera, F. Weber,
M. Alford, Phys. Rev. C93, 045812, 2016. [arXiv:1512.09183].