COMMON ENVELOPE SIMULATIONS

Here are some notes on putting a jet into the simulation.

Movies of outflow added to a Bondi accretion setup with

Computational units are: density scale = cm-3, time scale = yr, length scale = AU

1) Fixed grid outflow with particle at center.

  • Solution without outflow (not shown) adjusts and then is stable, approximating Bondi accretion.
  • Subgrid accretion routine is set to Krumholz.
  • Fixed grid, resolution 643
  • Box dimension L = 10 AU
  • Ambient density 105 cm-3
  • Ambient temperature 370 K
  • Outflow parameters are:

Particle%Feedback%efficiency=1d0 —> all accreted mass goes into outflow
Particle%feedback%radius=16 —> outflow set every time step in bipolar regions of radius 16 cells
Particle%feedback%rsurface=0.01d0 —> jet assumed to be launched from 0.01 solar radii from the secondary (white dwarf surface)
Particle%feedback%jefficiency=1d0 —> all of accreted angular momentum goes into outflow (so none into spin of secondary)
Particle%feedback%collimation=pi/12 —> collimation angle
Particle%feedback%T=0d0 —> made jet have zero temperature
Particle%feedback%p=1 —> parameter that determines smoothness of jet edges
particle%feedback%spin_axes=(/0d0,0d0,1d0/) —> forces outflow axis to be z axis
particle%feedback%vfact=2d0 —> jet assumed to be launched with 2 times the Keplerian speed at launch radius

xz slice of density with velocity vectors

2) Next increased box size by factor of 4 to L = 40. Base resolution 643 and 2 levels AMR. Tested solution first without outflow. Not completely stable. Not surprising because accretion radius of 4 cells is now smaller with finer resolution around particle, so Krumholz underestimates Bondi accretion rate more.

xz slice of density
xz slice of density with velocity vectors

3) Same but now added outflow and initialized particle and gas with constant velocity.
xz slice of density
xz slice of density with velocity vectors relative to moving frame

4) Similar but now initialize particle with constant velocity but not gas.
xz slice of density
xz slice of density with velocity vectors

Discussion

  • The outflow prescription seems to work okay.
  • As a next step, I could go to a CE setup but in low resolution.
  • Control case would have no outflow but Krumholz accretion turned on (Krumholz just used for testing purposes, but we will change subgrid accretion model).
  • Then same thing but with outflow also turned on.

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