Longterm Evolution of Supernova Remnants SNR in Magnetized ISM

1
Long-term Evolution of Supernova Remnants (SNR)
in Magnetized ISM
Hidekazu Hanayama , Kohji Tomisaka
Department of Astronomy , University of Tokyo
Division of Theoretical Astrophysics , NAOJ
1. About SNR
E-mail hanayama_at_th.nao.ac.jp
4. Results
106 years
3106 years
Magnetic field B00µG
Shock wave
shell
Density
Hot gas
bubble
7104 years
Shell expands with Sonic velocity Vs
SNR 0509-67.5 by Chandra X-ray satellite
spherical expansion

• Evolution of SNRs is considered to have a very
  important
• influence on
• molecular cloud formation, star formation,
  heating and
• compression of interstellar cloud, acceleration
  of cosmic ray,
• turbulence motion.
• SNR is a remarkable interstellar phenomenon!

106 years
3106 years
Magnetic field B01µG
shell
Density
Sonic velocity Vs Alfven velocity VA(B01µG)
7104 years
bubble
2. My research
106 years
3106 years
Magnetic field B05µG

• Theoretical evolutions of supernova remnants in
  magnetic field
• with numerical simulations
• SNRs evolve in the interstellar magnetic field.
• 1D-MHD(Magnetic Hydrodynamics) simulation was
  already done.
• But it didnt include the global direction of
  magnetic field.
• I tried 2D-MHD simulation with more realistic
  model.

shell
Density
7104 years
bubble
Shell expands with Alfven velocity VA(B05µG)
2D Magnetic field lines
1D Magnetic field lines

• Hot bubble turns to shrink due to magnetic
  pressure in shells.

?
R-direction
Shell boundary
B05µG VA Alfven velocity 25km/s
Shell boundary
B00µG Vs Sonic velocity 10km/s
Bubble boundary
B00µG Slow shrink by decrease of thermal
pressure in hot bubble
Bubble boundary
B05µG Rapid shrink by magnetic pressure
Already known
Never known
3. Model Calculation
Z-direction
Shell boundary
B05µG expand with Vs Sonic velocity by no
effect of magnetic pressure
Shell boundary
2D cylindrical coordinates
B00µG same as R-direction
Bubble boundary
B00µG same as R-direction
Interstellar medium ?00.2cm-3,T0104K
Z-direction
B05µG expand with Vs Sonic velocity by no
effect of magnetic pressure
Bubble boundary
Shell Volume
Bubble Volume
Magnetic field lines B05µG
7104 years
Calculate region
n00.2,B05µG2D
n00.2,B05µG2D
Magnetic field lines B05µG
Density
n00.2,B05µG1D
n00.2,B05µG1D
n00.2,B01µG2D
n00.2,B01µG2D
R-direction
n00.2,B00µG2D
n00.2,B00µG2D
2500 grid 2500 grid 250 pc 250 pc
The volume of the shell increases with magnetic
fields. On the other hand, the volume of the
bubble decreases with magnetic fields. The
maximum volume of the bubble of 2D is smaller
than that of 1D.
Supernova explosion E051050erg
Ideal MHD equation
Strong heating from O,B star is working
Only weak heating from cosmic ray is working
Only weak heating from cosmic ray is working
Strong heating from O,B star is working
No magnetic field exists
Magnetic field B05µG exists
No magnetic field exists
Magnetic field B05µG exists
Density
Density
Density
Density
2106 years
2106 years
2106 years
2106 years
Mostly the same !
Very different !
If heating is weak, the width of shell will
become narrow by the decrease of Sonic velocity,
and the boundary of bubble will spread more.
When there is a magnetic field(5µG), the magnetic
pressure has dominant influence and the evolution
of SNR does not change mostly.

• In long-term evolution, SNR gets to have
  anisotropy.
• After the decrease of ram pressure, shell
  expands
• with Alfven velocity to R-direction.
• Hot bubble shrinks due to magnetic pressure.
• The maximum volume of the bubble is smaller
• than that predicted by 1D simulation.
• Magnetic field makes influence of heating
• environment smaller.
• Theoretical data of SNR just comes to be able to
  be
• compared with the data of observation.

?0(T) radiative cooling function (collisional
ionization equilibrium) G0 strong heating from
O,B star or weak heating from cosmic ray mp
1.6710-24 g proton mass mu 1.4 mean
number density of hydrogen Code Modified CANS
(Coordinated Astronomical Numerical
Software) Scheme Modified Lax-Wendroff
Raymond, Cox Smith 1976