Inhomogeneous Jets from Neutron Star Mergers: One Jet to Rule them all. (arXiv:2201.09796v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Lamb_G/0/1/0/all/0/1">Gavin P Lamb</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nativi_L/0/1/0/all/0/1">Lorenzo Nativi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rosswog_S/0/1/0/all/0/1">Stephan Rosswog</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kann_D/0/1/0/all/0/1">D. Alexander Kann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Levan_A/0/1/0/all/0/1">Andrew Levan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lundman_C/0/1/0/all/0/1">Christoffer Lundman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tanvir_N/0/1/0/all/0/1">Nial Tanvir</a>
Using the resultant profiles from 3D hydrodynamic simulations of relativistic
jets interacting with neutron star merger wind ejecta, we show how the
inhomogeneity of energy and velocity {across the jet surface profile} can alter
the observed afterglow lightcurve. We find that the peak afterglow flux depends
sensitively on the observer’s line-of-sight, not only via the jet inclination
but also through the jet rotation: for an observer viewing the afterglow within
the GRB-bright jet core, we find a peak flux variability on the order $<0.5$
dex through rotational orientation and $<1.3$ dex for the polar inclination. An
observed afterglow’s peak flux can be used to infer the jet kinetic energy, and
where a top-hat jet is assumed, we find the range of inferred jet kinetic
energies for our various model afterglow lightcurves (with fixed model
parameters), covers $sim 1/3$ of the observed short GRB population.
Additionally, we present an analytic jet structure function that includes
physically motivated parameter uncertainties due to variability through the
rotation of the source. % An approximation for the change in collimation due to
the merger ejecta mass is included and we show that by considering the observed
range of merger ejecta masses from short GRB kilonova candidates, a population
of merger jets with a fixed intrinsic jet energy is capable of explaining the
observed broad diversity seen in short GRB afterglows.
Using the resultant profiles from 3D hydrodynamic simulations of relativistic
jets interacting with neutron star merger wind ejecta, we show how the
inhomogeneity of energy and velocity {across the jet surface profile} can alter
the observed afterglow lightcurve. We find that the peak afterglow flux depends
sensitively on the observer’s line-of-sight, not only via the jet inclination
but also through the jet rotation: for an observer viewing the afterglow within
the GRB-bright jet core, we find a peak flux variability on the order $<0.5$
dex through rotational orientation and $<1.3$ dex for the polar inclination. An
observed afterglow’s peak flux can be used to infer the jet kinetic energy, and
where a top-hat jet is assumed, we find the range of inferred jet kinetic
energies for our various model afterglow lightcurves (with fixed model
parameters), covers $sim 1/3$ of the observed short GRB population.
Additionally, we present an analytic jet structure function that includes
physically motivated parameter uncertainties due to variability through the
rotation of the source. % An approximation for the change in collimation due to
the merger ejecta mass is included and we show that by considering the observed
range of merger ejecta masses from short GRB kilonova candidates, a population
of merger jets with a fixed intrinsic jet energy is capable of explaining the
observed broad diversity seen in short GRB afterglows.
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