Prompt gamma-ray emission of GRB 170817A associated to GW 170817: A consistent picture
arXiv:1801.06124 · doi:10.1093/mnras/sty1246
Abstract
The short GRB 170817A associated to the first detection of gravitation waves from a Binary Neutron Star (BNS) merger was in many ways unusual. Possible explanations are emission from a cocoon or cocoon break out, off-axis view of a structured or uniform jet, and on-axis ultra-relativistic jet with reduced density and Lorentz factor. Here we use a phenomenological model of shock evolution and synchrotron/self-Compton emission to simulate the prompt emission of GRB 170817A and to test above proposals. We find that synchrotron emission from a mildly relativistic cocoon with a Lorentz factor of 2-3, as considered in the literature, generates a too soft, too long, and too bright prompt emission. Off-axis view of an structured jet with a Lorentz factor of about 10 can reproduce observations, but needs a very efficient transfer of kinetic energy to electrons in internal shocks, which is disfavored by particle in cell simulations. We also comment on cocoon breakout as a mechanism for generation of the prompt gamma-ray. A relativistic jet with a Lorentz factor of about 100 and a density lower than typical short GRBs seems to be the most plausible model and we conclude that GRB 170817A was intrinsically faint. Based on this result and findings of relativistic magnetohydrodynamics simulations of BNS merger in the literature we discuss physical and astronomical conditions, which may lead to such faint short GRBs. We identify small mass difference of progenitor neutron stars, their old age and reduced magnetic field, and anti-alignment of spin-orbit angular momentum induced by environmental gravitational disturbances during the lifetime of the BNS as causes for the faintness of GRB 170817A. We predict that BNS mergers at lower redshifts generate on average fainter GRBs.
41 pages, 8 figures. v3: version accepted for publication in MNRAS
References in corpus (53)
- GW170817: Observation of Gravitational Waves from a Binary Neutron Star Inspiral
- Multi-messenger Observations of a Binary Neutron Star Merger
- Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
- An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A
- Origin of the heavy elements in binary neutron-star mergers from a gravitational wave event
- The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/VIRGO GW170817. II. UV, Optical, and Near-IR Light Curves and Comparison to Kilonova Models
- Spectroscopic identification of r-process nucleosynthesis in a double neutron star merger
- The X-ray counterpart to the gravitational wave event GW 170817
- A kilonova as the electromagnetic counterpart to a gravitational-wave source
- The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
- Constraints on a phenomenologically parameterized neutron-star equation of state
- Physics of Strongly Magnetized Neutron Stars
- Illuminating Gravitational Waves: A Concordant Picture of Photons from a Neutron Star Merger
- Optical emission from a kilonova following a gravitational-wave-detected neutron-star merger
- The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Dark Energy Camera Discovery of the Optical Counterpart
- A Radio Counterpart to a Neutron Star Merger
- The discovery of the electromagnetic counterpart of GW170817: kilonova AT 2017gfo/DLT17ck
- Magnetic acceleration of ultra-relativistic jets in gamma-ray burst sources
- A mildly relativistic wide-angle outflow in the neutron star merger GW170817
- Late time afterglow observations reveal a collimated relativistic jet in the ejecta of the binary neutron star merger GW170817
- The Third Swift Burst Alert Telescope Gamma-Ray Burst Catalog
- Three-dimensional GRMHD simulations of the remnant accretion disks from neutron star mergers: outflows and r-process nucleosynthesis
- Binary Neutron Star Mergers: Dependence on the Nuclear Equation of State
- The outflow structure of GW170817 from late time broadband observations
- High resolution numerical-relativity simulations for the merger of binary magnetized neutron stars
- Three-dimensional GRMHD simulations of neutrino-cooled accretion disks from neutron star mergers
- A cocoon shock breakout as the origin of the -ray emission in GW170817
- Off-axis emission of short gamma-ray bursts and the detectability of electromagnetic counterparts of gravitational wave detected binary mergers
- Gravitational waves and mass ejecta from binary neutron star mergers: Effect of the mass-ratio
- Relativistic simulations of black hole-neutron star coalescence: the jet emerges
- Electromagnetic Counterparts to Structured Jets from Gravitational Wave Detected Mergers
- Off-axis short GRBs from structured jets as counterparts to GW events
- Detecting binary neutron star systems with spin in advanced gravitational-wave detectors
- Black hole-neutron star binary merger: Dependence on black hole spin orientation and equations of state
- The origin of the first neutron star -- neutron star merger
- On the Progenitor of Binary Neutron Star Merger GW170817
- Binary Neutron Star Mergers and Short Gamma-Ray Bursts: Effects of Magnetic Field Orientation, Equation of State, and Mass Ratio
- The unpolarized macronova associated with the gravitational wave event GW170817
- A hot cocoon in the ultralong GRB 130925A: hints of a PopIII-like progenitor in a low density wind environment
- GRMHD simulations of prompt-collapse neutron star mergers: the absence of jets
- Dynamical ejecta from precessing neutron star-black hole mergers with a hot, nuclear-theory based equation of state
- Star Formation Rates from [CII] 158 um and Mid Infrared Emission Lines for Starbursts and AGN
- Distance and properties of NGC 4993 as the host galaxy of a gravitational wave source, GW170817
- A comparison between SALT/SAAO observations and kilonova models for AT 2017gfo: the first electromagnetic counterpart of a gravitational wave transient - GW170817
- Thermal and non-thermal emission from the cocoon of a gamma-ray burst jet
- The role of weak interactions in dynamic ejecta from binary neutron star mergers
- Welcome to the Multi-Messenger Era! Lessons from a Neutron Star Merger and the Landscape Ahead
- Molecular-Cloud-Scale Chemical Composition II: Mapping Spectral Line Survey toward W3(OH) in the 3 mm Band
- The optical afterglow of the short gamma-ray burst associated with GW170817
- Numerical models of blackbody-dominated gamma-ray bursts -- II. Emission properties
- Numerical models of blackbody-dominated gamma-ray bursts -- I. Hydrodynamics and the origin of the thermal emission
- Multidimensional simulations of magnetic field amplification and electron acceleration to near-energy equipartition with ions by a mildly relativistic quasi-parallel plasma collision
- GRBs have preferred jet opening angles and bulk Lorentz factors