Gravity seminar - Jan-Erik Christian Seminar

Event details

Title: Impossible Twin Stars - How can we see phase transitions?

Abstract: Neutron stars are, apart from black holes, the densest objects in the universe and, as such, prime laboratories for investigations of the behaviour of matter at high densities. One prospect in this density regime is the occurrence of a phase transition from hadronic to quark matter. In this talk, we will explore the possibility of such a first-order phase transition and, maybe more importantly, discuss how such a phase transition could (fail to) communicate its presence. To this end, we will combine a highly parameterizable, yet well motivated hadronic equation of state (EoS) with two different quark matter descriptions, one of which is highly idealized, while the other one is more realistic. This approach does lead to better agreement with astrophysical constraints, but cannot be interpreted as an unambiguous signal for a phase transition. The clearest indication derived for the presence of a phase transition are so-called twin stars, where two neutron stars have the same mass, but different radii. However, we find that current astrophysical constrains significantly curtail the parameter space where twin stars can be constructed. Finally, we will discuss how this problem is compounded when considering the thermal evolution of proto-neutron stars.