AT2017gfo: Bayesian inference and model selection of multi-component kilonovae and constraints on the neutron star equation of state. (arXiv:2101.01201v2 [astro-ph.HE] UPDATED)

AT2017gfo: Bayesian inference and model selection of multi-component kilonovae and constraints on the neutron star equation of state. (arXiv:2101.01201v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Breschi_M/0/1/0/all/0/1">Matteo Breschi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Perego_A/0/1/0/all/0/1">Albino Perego</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bernuzzi_S/0/1/0/all/0/1">Sebastiano Bernuzzi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pozzo_W/0/1/0/all/0/1">Walter Del Pozzo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nedora_V/0/1/0/all/0/1">Vsevolod Nedora</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Radice_D/0/1/0/all/0/1">David Radice</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vescovi_D/0/1/0/all/0/1">Diego Vescovi</a>

The joint detection of the gravitational wave GW170817, of the short
$gamma$-ray burst GRB170817A and of the kilonova AT2017gfo, generated by the
the binary neutron star merger observed on August 17, 2017, is a milestone in
multimessenger astronomy and provides new constraints on the neutron star
equation of state. We perform Bayesian inference and model selection on
AT2017gfo using semi-analytical, multi-components models that also account for
non-spherical ejecta. Observational data favor anisotropic geometries to
spherically symmetric profiles, with a log-Bayes’ factor of ${sim}10^{4}$, and
favor multi-component models against single-component ones. The best fitting
model is an anisotropic three-component composed of dynamical ejecta plus
neutrino and viscous winds. Using the dynamical ejecta parameters inferred from
the best-fitting model and numerical-relativity relations connecting the ejecta
properties to the binary properties, we constrain the binary mass ratio to
$q<1.54$ and the reduced tidal parameter to $120<tildeLambda<1110$. Finally,
we combine the predictions from AT2017gfo with those from GW170817,
constraining the radius of a neutron star of $1.4~{rm M}_odot$ to
$12.2pm0.5~{rm km}$ ($1sigma$ level). This prediction could be further
strengthened by improving kilonova models with numerical-relativity
information.

The joint detection of the gravitational wave GW170817, of the short
$gamma$-ray burst GRB170817A and of the kilonova AT2017gfo, generated by the
the binary neutron star merger observed on August 17, 2017, is a milestone in
multimessenger astronomy and provides new constraints on the neutron star
equation of state. We perform Bayesian inference and model selection on
AT2017gfo using semi-analytical, multi-components models that also account for
non-spherical ejecta. Observational data favor anisotropic geometries to
spherically symmetric profiles, with a log-Bayes’ factor of ${sim}10^{4}$, and
favor multi-component models against single-component ones. The best fitting
model is an anisotropic three-component composed of dynamical ejecta plus
neutrino and viscous winds. Using the dynamical ejecta parameters inferred from
the best-fitting model and numerical-relativity relations connecting the ejecta
properties to the binary properties, we constrain the binary mass ratio to
$q<1.54$ and the reduced tidal parameter to $120<tildeLambda<1110$. Finally,
we combine the predictions from AT2017gfo with those from GW170817,
constraining the radius of a neutron star of $1.4~{rm M}_odot$ to
$12.2pm0.5~{rm km}$ ($1sigma$ level). This prediction could be further
strengthened by improving kilonova models with numerical-relativity
information.

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