Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermodynamics conditions of matter in neutron star mergers   Matter in neutron star collisions can reach densities up to few times the
nuclear saturation threshold and temperatures up to one hundred MeV.
Understanding the structure and composition of such matter requires many-body
nonperturbative calculations that are currently highly uncertain.Unique
constraints on the neutron star matter are provided by gravitational-wave
observations aided by numerical relativity simulations. In this work, we
explore the thermodynamical conditions of matter and radiation along the merger
dynamics. We consider 3 microphysical equation of state models and numerical
relativity simulations including an approximate neutrino transport scheme. The
neutron star cores collision and their multiple centrifugal bounces heat the
initially cold matter to several tens of MeV. Streams of hot matter with
initial densities $\sim1-2\rho_0$ move outwards and cool due to decompression
and neutrino emission. The merger can result in a neutron star remnant with
densities up to $3-5\rho_0$ and temperatures $\sim 50$~MeV. The highest
temperatures are confined in an approximately spherical annulus at densities
$\sim\rho_0$. Such temperatures favour positron-neutron capture at densities
$\sim\rho_0$, thus leading to a neutrino emission dominated by electron
antineutrinos. We study the impact of trapped neutrinos on the remnant matter's
pressure, electron fraction and temperature and find that it has a negligible
effect. Disks around neutron star or black hole remnant are neutron rich and
not isentropic, but they differ in size, entropy and lepton fraction depending
on the nature of the central object. In presence of a black hole, disks are
smaller and mostly transparent to neutrinos; in presence of a massive neutron
star, they are more massive, geometrically and optically thick.

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The categories of this paper are: q-fin
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: supr-con
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The categories of this paper are: math-ph
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg