ABSTRACT The joint detection of the gravitational wave GW170817, of the short γray burst GRB170817A and of the kilonova AT2017gfo, generated by the the binary neutron star (NS) merger observed on 2017 August 17, is a milestone in multimessenger astronomy and provides new constraints on the NS equation of state. We perform Bayesian inference and model selection on AT2017gfo using semianalytical, multicomponents models that also account for nonspherical ejecta. Observational data favour anisotropic geometries to spherically symmetric profiles, with a logBayes’ factor of ∼104, and favour multicomponent models against singlecomponent ones. The bestfitting model is an anisotropic threecomponent composed ofmore »
Comparing inclinationdependent analyses of kilonova transients
ABSTRACT The detection of the optical transient AT2017gfo proved that binary neutron star mergers are progenitors of kilonovae (KNe). Using a combination of numericalrelativity and radiativetransfer simulations, the community has developed sophisticated models for these transients for a wide portion of the expected parameter space. Using these simulations and surrogate models made from them, it has been possible to perform Bayesian inference of the observed signals to infer properties of the ejected matter. It has been pointed out that combining inclination constraints derived from the KN with gravitationalwave measurements increases the accuracy with which binary parameters can be estimated, in particular breaking the distanceinclination degeneracy from gravitational wave inference. To avoid bias from the unknown ejecta geometry, constraints on the inclination angle for AT2017gfo should be insensitive to the employed models. In this work, we compare different assumptions about the ejecta and radiative reprocesses used by the community and we investigate their impact on the parameter inference. While most inferred parameters agree, we find disagreement between posteriors for the inclination angle for different geometries that have been used in the current literature. According to our study, the inclusion of reprocessing of the photons between different ejecta types improves the modeling more »
 Publication Date:
 NSFPAR ID:
 10279145
 Journal Name:
 Monthly Notices of the Royal Astronomical Society
 Volume:
 502
 Issue:
 2
 Page Range or eLocationID:
 3057 to 3065
 ISSN:
 00358711
 Sponsoring Org:
 National Science Foundation
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