Simulations of ultrarelativistic magnetodynamic jets from gamma‐ray burst engines

By A. Tchekhovskoy, J. McKinney, Ramesh Narayan Harvard CfAITC, Stanford UniversityKIPAC. 2008

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Long-duration gamma-ray bursts (GRBs) require an engine capable of driving a jet of plasma to ultrarelativistic bulk Lorentz factors of up to several hundred and into narrow opening angles of a few degrees. We use global axisymmetric stationary solutions of magnetically dominated (force-free) ultrarelativistic jets to test whether the popular magnetic-driving paradigm can generate the required Lorentz factors and opening angles. Our global solutions are obtained via time-dependent relativistic ideal magnetodynamical numerical simulations which follow the jet from the central engine to beyond six orders of magnitude in radius. Our model is primarily motivated by the collapsar model, in which a jet is produced by a spinning black hole or neutron star and then propagates through a massive stellar envelope. We find that the size of the pre-supernova progenitor star and the radial profile of pressure inside the star determine the terminal Lorentz factor and opening angle of the jet. At the radius where the jet breaks out of the star, our well-motivated fiducial model generates a Lorentz factor γ ∼ 400 and a half-opening angle Oj ∼ 2°, consistent with observations of many long-duration GRBs. Other models with slightly different parameters give y in the range 100-5000 and θ j from 0°1 to 10°, thus reproducing the range of properties inferred for GRB jets. A potentially observable feature of some of our solutions is that the maximum Poynting flux in the jet is found at 0 ∼ θ j with the jet power concentrated in a hollow cone, while the maximum in the Lorentz factor occurs at an angle 0 substantially smaller than θ j also in a hollow cone. We derive approximate analytical formulae for the radial and angular distribution of y and the radial dependence of θ j . These formulae reproduce the simulation results and allow us to predict the outcome of models beyond those simulated. We also briefly discuss applications to active galactic nuclei, X-ray binaries and short-duration GRBs.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/aaa225591674f0ebcd9d672f14df47092ae0781f

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Citations in the corpus

Kinematics of the jet in M 87 on scales of 100–1000 Schwarzschild radii (2016, background): “For the case of disk launching, we expect differential rotation and Tchekhovskoy et al. (2008) found γ < R under these conditions.”
BLACK HOLE SPIN AND THE RADIO LOUD/QUIET DICHOTOMY OF ACTIVE GALACTIC NUCLEI (2009, methodology): “Two of these are the field line angular velocity Ω(Ψ) and the enclosed poloidal current I (Ψ) (Tchekhovskoy et al. 2008).”
The physics of gamma-ray bursts & relativistic jets (2014, background): “…the magnetic jet launching mechanism, propagation and acceleration (e.g. Komissarov, 2001, 2004; McKinney, 2006; Komissarov, 2007; Komissarov et al., 2007; McKinney and Narayan, 2007; Tchekhovskoy et al., 2008; Komissarov et al., 2009; McKinney and Blandford, 2009; Tchekhovskoy et al., 2009, 2010).”
Fast TeV variability in blazars: jets in a jet (2009, background): “2008; see also Tchekhovskoy et al. 2008 for force-free simulations) show that if the pressure of the external medium provides a collimating funnel, the acceleration is efficient, in contrast to the case of a less collimating external pressure.”
Magnetic acceleration of ultrarelativistic jets in gamma-ray burst sources (2008, background): “In this case the collimation might be attained smoothly, with the disc-driven and central objectdriven components constituting parts of a coherent outflow configuration (e.g. Tchekhovskoy et al. 2008).”
Superradiance (2015, background): “[788, 773, 789, 790, 791]) and recent GRMHD simulations seem to indicate that magnetic fields generated by accretion disks have large split monopole components [778, 779, 780] suggesting that the BZ mechanism should occur in fully dynamical setups.”
Neutrino-dominated accretion flows as the central engine of gamma-ray bursts (2017, methodology): “…= f (a∗)cr 2 g B2 in 8π , (52) where f (a∗) is a factor depending on the specific configuration of the magnetic field including the information of the field configuration (e.g., Tchekhovskoy et al. 2008; Kawanaka et al. 2013b), and Bin is the poloidal magnetic field strength near the horizon.”
Superradiance: Energy Extraction, Black-Hole Bombs and Implications for Astrophysics and Particle Physics (2015, background): “[455, 442, 456, 457, 458]) and recent GRMHD simulations seem to indicate that magnetic fields generated by accretion disks have large split monopole components [445, 446, 447] suggesting that the BZ mechanism should occur in fully dynamical setups.”
The Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project (2019, methodology): “For illustrative purposes, we also overplot flux- functions of the approximate force-free solutions discussed in Tchekhovskoy et al. (2008) and Nakamura et al. (2018): ( ) ( ( )) ( ) ⎛ ⎝⎜ ⎞ ⎠⎟q qY = - k r r r , 1 cos .”
THE INTERNAL-COLLISION-INDUCED MAGNETIC RECONNECTION AND TURBULENCE (ICMART) MODEL OF GAMMA-RAY BURSTS (2010, background): “Recent numerical simulations (Tchekhovskoy et al. 2008; Nagataki 2009) suggest that a high-σ flow at the base of the flow would become a moderate-σ flow as it escapes the star (cf. Wheeler et al. 2000).”
Relativistic MHD simulations of core-collapse GRB jets: 3D instabilities and magnetic dissipation (2015, background): “In such jets, the lab-frame toroidal magnetic field can be approximated as (Beskin 1997; Narayan et al. 2007; Tchekhovskoy et al. 2008), − Bφ ' E = ΩRBp/c, (6) where Ω is the angular frequency of the central object, and Bp ≡ (B2R + B 2 z ) 1/2 and Bφ are the lab-frame magnetic field strengths of…”
Unveiling the origin of X-ray flares in gamma-ray bursts (2010, background): “At large distance where the jet interacts with the external medium the jet may remain extremely magnetized (as in the electromagnetic model of Lyutikov & Blandford 2003) or moderately magnetized (e.g. Drenkhahn & Spruit 2002; Tchekhovskoy et al. 2008).”
A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation (2010, methodology): “…generalized axisymmetric steady-state jet solution is presented as based upon approximate analytical solutions that have been confirmed numerically (Tchekhovskoy et al. 2008, 2009, 2010b) using the HARM code (Gammie, McKinney & Tóth 2003; Noble et al. 2006; Mignone & McKinney 2007; Tchekhovskoy,…”
ASYMPTOTIC STRUCTURE OF POYNTING-DOMINATED JETS (2009, methodology): “Both an analytical solution for the paraboloidal flux surfaces (Blandford 1976; Beskin & Nokhrina 2006) and numerical simulations (Komissarov et al. 2007, 2009; Tchekhovskoy et al. 2008) show that this is a good approximation for such jets.”
Stability of relativistic jets from rotating, accreting black holes via fully three-dimensional magnetohydrodynamic simulations (2008, background): “10%, which is evidence of an accurate solution (Tchekhovskoy et al. 2008).”
EFFICIENCY OF MAGNETIC TO KINETIC ENERGY CONVERSION IN A MONOPOLE MAGNETOSPHERE (2009, methodology): “If the jet remains highly-magnetized far from such confining media and passes far beyond the light cylinder, then the magnetic field geometry will become approximately monopolar (e.g. McKinney 2006b; Tchekhovskoy et al. 2008).”
THE STRUCTURE OF THE M87 JET: A TRANSITION FROM PARABOLIC TO CONICAL STREAMLINES (2011, background): “For a general (non-self-similar) case,b > 2 is allowed in 1 The original value is replaced by taking into account of the mass difference of SMBH. analytical and numerical models (Tchekhovskoy et al. 2008; Lyubarsky 2009; Komissarov et al. 2009).”