Can an Off-axis Gamma-Ray Burst Jet in GW170817 Explain All the Electromagnetic Counterparts?

Abstract

Gravitational waves from a merger of two neutron stars (NSs) were discovered for the first time in GW170817, together with diverse electromagnetic (EM) counterparts. To make constraints on a relativistic jet from the NS merger, we calculate the EM signals in (1) the short gamma-ray burst sGRB 170817A from an off-axis jet, (2) the optical-infrared macronova (or kilonova), especially the blue macronova, from a jet-powered cocoon, and (3) the X-ray and radio afterglows from the interaction between the jet and interstellar medium. We find that a typical sGRB jet is consistent with these observations, and there is a parameter space to explain all the observations in a unified fashion with an isotropic energy $\sim 10^{51}$-$10^{52}$ erg, opening angle $\sim 20^{\circ }$, and viewing angle $\sim 30^{\circ }$. The off-axis emission is less de-beamed than the point-source case because the viewing angle is comparable to the opening angle. We also analytically show that the jet energy accelerates a fair fraction of the merger ejecta to a sub-relativistic velocity $\sim 0.3$-$0.4$c as a cocoon in a wide parameter range. The ambient density might be low $\sim 10^{-3}$-$10^{-6}$ cm${}^{-3}$, which can be tested by future observations of radio flares and X-ray remnants.

arXiv comment25 pages, 6 figures, accepted for publication in PTEP

References in corpus (16)

• Modeling GW170817 based on numerical relativity and its implications
• Late time afterglow observations reveal a collimated relativistic jet in the ejecta of the binary neutron star merger GW170817
• Three-dimensional GRMHD simulations of the remnant accretion disks from neutron star mergers: outflows and r-process nucleosynthesis
• The outflow structure of GW170817 from late time broadband observations
• Global simulations of strongly magnetized remnant massive neutron stars formed in binary neutron star mergers
• A cocoon shock breakout as the origin of the $\gamma$-ray emission in GW170817
• The cocoon emission - an electromagnetic counterpart to gravitational waves from neutron star mergers
• Constraints on the ejecta of the GW170817 neutron-star merger from its electromagnetic emission
• Electromagnetic Counterparts to Structured Jets from Gravitational Wave Detected Mergers
• Off-axis prompt X-ray transients from the cocoon of short gamma-ray bursts
• Off-axis short GRBs from structured jets as counterparts to GW events
• Modeling Supernova-like Explosions Associated with Gamma-ray Bursts with Short Durations
• Numerically calibrated model for propagation of a relativistic unmagnetized jet in dense media
• A comparison between SALT/SAAO observations and kilonova models for AT 2017gfo: the first electromagnetic counterpart of a gravitational wave transient - GW170817
• Is the macronova in GW170817 powered by the central engine?
• Gravitational Waves from Binary Black Hole Mergers Inside of Stars

Cited by in corpus (15)

• Late time afterglow observations reveal a collimated relativistic jet in the ejecta of the binary neutron star merger GW170817
• Lessons from the short GRB170817A - the First Gravitational Wave Detection of a Binary Neutron Star Merger
• Late-time Evolution of Afterglows from Off-Axis Neutron-Star Mergers
• The short GRB 170817A: Modelling the off-axis emission and implications on the ejecta magnetization
• Merging Strangeon Stars
• Is the macronova in GW170817 powered by the central engine?
• Black hole-neutron star mergers using a survey of finite-temperature equations of state
• Mergers of black hole-neutron star binaries and rates of associated electromagnetic counterparts
• Signatures from a quasi-spherical outflow and an off-axis top-hat jet launched in a merger of compact objects: An analytical approach
• Gamma-ray burst models in light of the GRB 170817A - GW170817 connection
• Modeling Gamma-ray burst Afterglow observations with an Off-axis Jet emission
• Short GRBs Viewed from Far Off Axis
• Prompt emission from the counter jet of a short gamma-ray burst
• Gamma-Ray Bursts: Theoretical Issues and Developments
• Light curves of a shock-breakout material and a relativistic off-axis jet from a Binary Neutron Star system