TY - JOUR
T1 - Jet Dynamics in Compact Object Mergers
T2 - GW170817 Likely Had a Successful Jet
AU - Duffell, Paul C.
AU - Quataert, Eliot
AU - Kasen, Daniel
AU - Klion, Hannah
N1 - Funding Information:
We thank Brian Metzger, Juna Kollmeier, and Tony Piro for stimulating conversations that helped to motivate much of this work. We thank Wen-fai Fong, Ore Gottlieb, Andrew MacFadyen, and Rosalba Perna for useful conversations. This work was supported, in part, by the Theoretical Astrophysics Center at UC Berkeley. This research was also funded by the Gordon and Betty Moore Foundation through grant GBMF5076. E.Q. was supported in part by a Simons Investigator award from the Simons Foundation. H.K. is supported by a DOE Computational Science Graduate Fellowship under grant no. DE-FG02-97ER25308. Numerical computations utilized the Savio computational cluster resource provided by the Berkeley Research Computing program at the University of California, Berkeley (supported by the UC Berkeley Chancellor, Vice Chancellor of Research, and Office of the CIO).
Funding Information:
This research was also funded by the Gordon and Betty Moore Foundation through grant GBMF5076. E.Q. was supported in part by a Simons Investigator award from the Simons Foundation. H.K. is supported by a DOE Computational Science Graduate Fellowship under grant no. DE-FG02-97ER25308.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/10/10
Y1 - 2018/10/10
N2 - We use relativistic hydrodynamic numerical calculations to study the interaction between a jet and a homologous outflow produced dynamically during binary neutron star mergers. We quantify how the thermal energy imparted by the jet and the ability of the jet to escape the ejecta depend on the parameters of the jet engine and the ejecta. Under our assumptions, a collimated jet initiated at early times compared to the engine duration, we show that successful breakout of the forward cocoon shock necessitates a jet that successfully escapes the ejecta. This is because the ejecta is expanding, and the forward shock from a failed jet stalls before it reaches the edge of the ejecta. This conclusion can be circumvented only for very energetic wide angle jets, with parameters that are uncomfortable given short-duration GRB observations. For successful jets, we find two regimes of jet breakout from the ejecta: early breakout on timescales shorter than the engine duration, and late breakout well after the engine shuts off. A late breakout can explain the observed delay between gravitational waves and gamma rays in GW170817. We show that for the entire parameter space of jet parameters surveyed here (covering energies ∼1048-1051 erg and opening angles θ j ∼ 0.07-0.4) the thermal energy deposited by the jet is less than that produced by r-process heating on second timescales by at least an order of magnitude. Shock heating is thus energetically subdominant in setting the luminosity of thermally powered transients coincident with neutron star mergers (kilonovae).
AB - We use relativistic hydrodynamic numerical calculations to study the interaction between a jet and a homologous outflow produced dynamically during binary neutron star mergers. We quantify how the thermal energy imparted by the jet and the ability of the jet to escape the ejecta depend on the parameters of the jet engine and the ejecta. Under our assumptions, a collimated jet initiated at early times compared to the engine duration, we show that successful breakout of the forward cocoon shock necessitates a jet that successfully escapes the ejecta. This is because the ejecta is expanding, and the forward shock from a failed jet stalls before it reaches the edge of the ejecta. This conclusion can be circumvented only for very energetic wide angle jets, with parameters that are uncomfortable given short-duration GRB observations. For successful jets, we find two regimes of jet breakout from the ejecta: early breakout on timescales shorter than the engine duration, and late breakout well after the engine shuts off. A late breakout can explain the observed delay between gravitational waves and gamma rays in GW170817. We show that for the entire parameter space of jet parameters surveyed here (covering energies ∼1048-1051 erg and opening angles θ j ∼ 0.07-0.4) the thermal energy deposited by the jet is less than that produced by r-process heating on second timescales by at least an order of magnitude. Shock heating is thus energetically subdominant in setting the luminosity of thermally powered transients coincident with neutron star mergers (kilonovae).
KW - ISM: jets and outflows
KW - gamma-ray burst: general
KW - gravitational waves
KW - hydrodynamics
KW - relativistic processes
KW - shock waves
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U2 - 10.3847/1538-4357/aae084
DO - 10.3847/1538-4357/aae084
M3 - Article
AN - SCOPUS:85055285427
SN - 0004-637X
VL - 866
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 3
ER -