Jin Matsumoto. Numerical Experiments of GRB Jets. RIKEN Astrophysical Big Bang Laboratory

Transcription

1 Numerical Experiments of GRB Jets Jin Matsumoto RIKEN Astrophysical Big Bang Laboratory Collaborators: Nagataki, Ito, Mizuta, Barkov, Dainotti, Teraki (RIKEN)

2 Schematic Picture of the GRB Jet Meszaros 01 Central engine MHD process Extraction of the rotational energy of the BH or accretion disk through B-field thermal process -annihilation -annihilation fireball relativistic jet is launched from the central engine associated the death of the massive star The dynamics and stability of the relativistic jet is important in order to understand the GRB emissions.

3 First Simulation of GRB Jet Propagation Aloy et al inside star: collimation by cocoon outside star: drastic acceleration adiabatic expansion: energy conversion from Bernoulli equation: to

4 3D calculation: Zhang log rho (g/cm^3) 0.2 Model 2T, 9s 2D 0.2 Model 3BS, 9s 3D % asymmetry y (10^11 cm) Model 3A, 9s the initial conditions have cylindrical symmetry 3D Model 3BL, 8s % asymmetry 3D z (10^11 cm) The dynamics of the jet does not drastically change in between 2D and 3D

5 3D calculation: Zhang with precession Model 3P3, 8s log rho Model 3P3, 8s gamma inclination angle Model 0.2 3P5, 0.4 8s Model 0.2 3P5, 0.4 8s y (10^11 cm) Model 0.2 3P10, s Model 0.2 3P10, s z (10^11 cm) The jet is decelerated due to the material mixing between the jet and surrounding medium.

6 3D calculation: Lopez-Camara D 3D The relativistic jet can propagate and break out the progenitor star while remaining relativistic without the dependence of the resolution. The amount of turbulence and variability observed in the simulations is greater at higher resolutions. Jet properties are only marginally affected by the dimensionality.

7 Oscillation Induced RTI and RMI jet cross section JM & Masada 2013 radial oscillation motion of the jet growth of the Rayleigh-Taylor and Richtmyer-Meshkov instabilities These instabilities grow in GRB jet?

8 3D simulation: propagation of the relativistic jet focusing on the impact of the oscillation-induced Rayleigh-Taylor and Richtmyer-Meshkov instabilities (JM & Masada 2013) on the 3D jet propagation.

9 progenitor: 16TI model (Woosley & Heger 06)

10 Basic Equations mass conservation momentum conservation energy conservation specific enthalpy ratio of specific heats Lorentz factor

11 3D HD GRB Jet Propagation

12 Finger-like structures inside star Finger like structures are excited at the interface between the jet and cocoon.

13 Finger-like structures inside star Finger like structures are excited at the interface between the jet and cocoon.

14 3D simulations: evolution of the cross section of the relativistic jet

15 (a) Side View un-shocked ambient medium shocked ambient medium Jet cocoon z1 z2 z3 contact discontinuity (CD) P1 P3 P2 JM& Masada 13 bow shock Z many numerical works in order to investigate the propagation dynamics of the relativistic jet (e.g., Marti+ 97, Aloy+ 00, Zhang+ 03,04, Mizuta+ 06, Perucho+ 08, Morsony+07, Lazzati+ 09, Lopez- Camara+ 13) reconfinement shock in the collimated jet (Norman et al. 1982; Sanders 1983) reconfinement radial oscillating motion and region repeated excitation of the reconfinement region (e.g., (b) Top View Gomez+ 97, JM+ 12, Mizuta+ 14) (b1) Expansion Phase [z=z1] (b2) Contraction Phase (I) [z=z2] (b3) Contraction Phase (II) [z=z3] expanding CD contracting CD contracting CD P3 adiabatic cooling P2 P1 expanding shock contracting shock expanding shock [P1 < P2 < P3] [P1 < P2 < P3] [P2 < P3 < P1]

16 Growth of RTI in SN Explosion The condition for the RTI heavy fluid, (Chevalier 76) light fluid It is well known that a contact discontinuity, formed where a heavy fluid is supported above a light fluid against gravity, is unstable to perturbations to the boundary between the two fluids. Although the gravity is negligible in SN explosions, the acceleration of the gas works as a gravity.

17 Growth of RTI in SN Explosion The condition for the RTI for a compressible fluid in the absence of the gravity is given by Ono+13, (Chevalier 76) Ebisuzaki+89 He/H interface C+O/He interface

18 The mechanism of the growth of RTI The effective inertia is important. relativistically hot plasma: effective inertia: In addition to the growth of the Rayleigh-Taylor instability, the growth of the Richtmyer-Meshkov instability is also contributed to the finger like structures.

19 (a) Side View z1 z2 z3 Z many numerical works in order to investigate the un-shocked JM& Masada 13 ambient medium propagation dynamics of the relativistic jet shocked ambient medium (e.g., Marti+ 97, Aloy+ 00, Zhang+ 03,04, Mizuta+ 06, cocoon Perucho+ 08, Morsony+07, P3 Lazzati+ 09, Lopez- Jet P2 Camara+ 13) reconfinement shock in the P1 collimated jet (Norman et al. 1982; contact Sanders 1983) reconfinement discontinuity (CD) radial oscillating motion and region repeated excitation of the reconfinement region (e.g., (b) Top View Gomez+ 97, JM+ 12, Mizuta+ 14) (b1) Expansion Phase [z=z1] (b2) Contraction Phase (I) [z=z2] (b3) Contraction Phase (II) [z=z3] expanding CD contracting CD contracting CD bow shock P3 adiabatic cooling P2 P1 expanding shock contracting shock expanding shock [P1 < P2 < P3] [P1 < P2 < P3] [P2 < P3 < P1]

20 Richtmyer-Meshkov Instability contact discontinuity 0 The Richtmyer-Meshkov instability is induced by impulsive acceleration due to shock passage. The perturbation amplitude grows linearly in time (Richtmyer 1960),

21 Numerical Setting: 3D Toy Model We considered the spatial evolution to the jet direction. 1% perturbation in the pressure periodic boundary 10 cylindrical coordinate relativistic jet (z-direction) ideal gas numerical scheme: HLLC (Mignone & Bodo 05) periodic boundary

22 Result: Density Since the jet is overpressured initially, at the early evolutional stage the jet starts to expand. Finger-like structure emerges at the jet-external medium interface primally due to the RTI. growth of the oscillation-induced RTI and RMI at the jet interface RMI fingers are excited secondary between the RTI fingers. log ρ 0.5 During the radial oscillating motion of the jet, the two types of finger structures are amplified and repeatedly excited at the jet interface, and finally deform the transverse structure of the jet. unit in time:

23 Synergetic Growth of Rayleigh-Taylor and Richtmyer-Meshkov Instabilities development of the Rayleigh-Taylor instability at the jet interface increases exponentially. excitation of the Richtmyer-Meshkov instability at the jet interface grows linearly with time.

24 Finger-like structures inside star Finger like structures are excited at the interface between the jet and cocoon.

25 Growth of RTI and RMI outside star Growth of the RTI and RMI is also observed after the jet breaks out the progenitor star.

26 2D simulation: propagation of the relativistic MHD jet

27 Toy Model for MHD Jet: Pure Toroidal density pressure progenitor: 16TI model (Woosley & Heger 06) + stellar wind Asahina et al. 2014

28 Basic Equations mass conservation momentum conservation energy conservation induction equation momentum density vector energy density specific enthalpy ratio of specific heats Lorentz factor

29 hydro case: σ=0 axisymmetric consistent with previous studies - Jet successfully drills through the progenitor star - drastically accelerated after jet breaks out of the stellar surface

30 Model: σ=10 axisymmetric Jet reaches the progenitor surface the progenitor surface faster. Maximum Lorentz factor is almost same as pure hydro case.

31 HD vs MHD jet nose cone (Leismann et al. 2005) formation of nose cone confinement of hot gas low Lorentz factor hoop stress

32 HD vs MHD jet Pure toroidal magnetic field is not responsible for the further acceleration of the jet compared to the pure hydro jet.

33 Summary Basic physics of the propagation of the relativistic jet is investigated though 3D HD/2D MHD numerical simulations. 3D HD GRB jet A pressure mismatch between the jet and surrounding medium leads to the radial oscillating motion of the jet. The jet-external medium interface is unstable due to the oscillation-induced Rayleigh-Taylor instability Richtmyer-Meshkov instability 2D MHD GRB jet A nose cone is formed between forward and reverse shocks. Lorentz factor of the nose cone is smaller than the jet core. Pure toroidal magnetic field is not responsible for the further acceleration of the jet compared to pure hydro jet. Next Study: more realistic situation for relativistic MHD jets in the context of GRBs