Equation-of-state Constraints and the QCD Phase Transition in the Era of Gravitational-Wave Astronomy. (arXiv:1904.01306v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bauswein_A/0/1/0/all/0/1">Andreas Bauswein</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bastian_N/0/1/0/all/0/1">Niels-Uwe Friedrich Bastian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Blaschke_D/0/1/0/all/0/1">David Blaschke</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chatziioannou_K/0/1/0/all/0/1">Katerina Chatziioannou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Clark_J/0/1/0/all/0/1">James Alexander Clark</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fischer_T/0/1/0/all/0/1">Tobias Fischer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Janka_H/0/1/0/all/0/1">Hans-Thomas Janka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Just_O/0/1/0/all/0/1">Oliver Just</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Oertel_M/0/1/0/all/0/1">Micaela Oertel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stergioulas_N/0/1/0/all/0/1">Nikolaos Stergioulas</a>
We describe a multi-messenger interpretation of GW170817, which yields a
robust lower limit on NS radii. This excludes NSs with radii smaller than about
10.7 km and thus rules out very soft nuclear matter. We stress the potential of
this type of constraints when future detections become available. A very
similar argumentation may yield an upper bound on the maximum mass of
nonrotating NSs. We also discuss simulations of NS mergers, which undergo a
first-order phase transition to quark matter. We point out a different
dynamical behavior. Considering the gravitational-wave signal, we identify an
unambiguous signature of the QCD phase transition in NS mergers. The occurrence
of quark matter through a strong first-order phase transition during merging
leads to a characteristic shift of the dominant postmerger frequency. The
frequency shift is indicative for a phase transition if it is compared to the
postmerger frequency which is expected for purely hadronic EoS models. A very
strong deviation of several 100 Hz is observed for hybrid EoSs in an otherwise
tight relation between the tidal deformability and the postmerger frequency. We
address the potential impact of a first-order phase transition on the
electromagnetic counterpart of NS mergers. Our simulations suggest that there
would be no significant qualitative differences between a system undergoing a
phase transition to quark matter and purely hadronic mergers. The quantitative
differences are within the spread which is found between different hadronic EoS
models. This implies on the one hand that GW170817 is compatible with a
possible transition to quark matter. On the other hand these considerations
show that it may not be easy to identify quantitative differences between
purely hadronic mergers and events in which quark matter occurs considering
solely their electromagnetic counterpart or their nucleosynthesis products.
(abridged)
We describe a multi-messenger interpretation of GW170817, which yields a
robust lower limit on NS radii. This excludes NSs with radii smaller than about
10.7 km and thus rules out very soft nuclear matter. We stress the potential of
this type of constraints when future detections become available. A very
similar argumentation may yield an upper bound on the maximum mass of
nonrotating NSs. We also discuss simulations of NS mergers, which undergo a
first-order phase transition to quark matter. We point out a different
dynamical behavior. Considering the gravitational-wave signal, we identify an
unambiguous signature of the QCD phase transition in NS mergers. The occurrence
of quark matter through a strong first-order phase transition during merging
leads to a characteristic shift of the dominant postmerger frequency. The
frequency shift is indicative for a phase transition if it is compared to the
postmerger frequency which is expected for purely hadronic EoS models. A very
strong deviation of several 100 Hz is observed for hybrid EoSs in an otherwise
tight relation between the tidal deformability and the postmerger frequency. We
address the potential impact of a first-order phase transition on the
electromagnetic counterpart of NS mergers. Our simulations suggest that there
would be no significant qualitative differences between a system undergoing a
phase transition to quark matter and purely hadronic mergers. The quantitative
differences are within the spread which is found between different hadronic EoS
models. This implies on the one hand that GW170817 is compatible with a
possible transition to quark matter. On the other hand these considerations
show that it may not be easy to identify quantitative differences between
purely hadronic mergers and events in which quark matter occurs considering
solely their electromagnetic counterpart or their nucleosynthesis products.
(abridged)
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