The Dense Matter Equation of State Is Important… Just Not for This Reason
The dense matter equation of state is required to describe matter at
ultrahigh densities. Its elucidation is one of the primary goals of nuclear
astrophysics. Neutron stars cooling off after siphoning gas from a binary
companion for months or longer, so called cooling transients, are one
available probe to constrain the dense matter equation of state. Models
calculating the cooling of the crust (the lattice of ions making up the
outer kilometer of the neutron star) can be compared with cooling transient
observations for such constraints. However, one lurking issue was that the
pressure (depth) at which the crust transitioned to the core (the uniform,
possibly exotic, matter comprising the bulk of the neutron star) is linked
to the dense matter equation of state and was thought to influence model
results for crust cooling. This would severely complicate model-observation
comparisons for cooling transient systems. In this work, we show that the crust-core
transition pressure does not significantly alter model calculation results
for cooling transients, thereby simplifying the associated model-observation
comparisons. This work was done in collaboration with Dr. Zach Meisel of the Ohio University and
Dr. Edward Brown of the Michigan State University.
The full work, published in the the Astrophysical Journal,
can be accessed here.
Model calculation details can be accessed here.
Nuclear Astrophysics
What is a neutron star composed of?
The dense matter equation of state is required to describe matter at
ultrahigh densities. Its elucidation is one of the primary goals of nuclear
astrophysics. Neutron stars cooling off after siphoning gas from a binary
companion for months or longer, so called cooling transients, are one
available probe to constrain the dense matter equation of state. Models
calculating the cooling of the crust (the lattice of ions making up the
outer kilometer of the neutron star) can be compared with cooling transient
observations for such constraints. However, one lurking issue was that the
pressure (depth) at which the crust transitioned to the core (the uniform,
possibly exotic, matter comprising the bulk of the neutron star) is linked
to the dense matter equation of state and was thought to influence model
results for crust cooling. This would severely complicate model-observation
comparisons for cooling transient systems. In this work, we show that the crust-core
transition pressure does not significantly alter model calculation results
for cooling transients, thereby simplifying the associated model-observation
comparisons. This work was done in collaboration with Dr. Zach Meisel of the Ohio University and
Dr. Edward Brown of the Michigan State University.
The full work, published in the the Astrophysical Journal,
can be accessed here.
Model calculation details can be accessed here.
