Hello, I'm recently interested in the kinetic feedback mechanism of SMBH in the TNG simulation.
If I understand it correctly, according to Weinberger et al. (2017), for each feedback event, a random gas cell is chosen, and the distance-weighted momentum is applied in a random direction. However, I couldn't find any information about the function of smoothing kernel w(r) and the random injection unit vector n.
If the n is totally random and the kernel is only a function of distance from the SMBH, then is the kinetic outflow in the TNG not a bipolar wind?
Also, can I assume the smoothing kernel is the SPH cubic spline kernel weighted by gas cell radius?
Thanks for your help!
edit:
I found another thread about the kinetic mode.
Still, I want to verify my understanding of the mechanism of the TNG since other simulations, such as the RAMSES, use the preferred direction to shoot the mass and momentum.
Dylan Nelson
8 Apr
(1) A single random gas cell is not chosen. Instead, momentum is given to all N nearest gas cells (N=256 for TNG100-1).
(2) Yes the kernel shape is the usual cubic spline, that depends only on distance.
(3) Yes the direction vector -for each event- is entirely random. So there are no preferred directions, and energy is not injected in a bipolar geometry (although outflows can then naturally emerge as bipolar, see e.g. https://arxiv.org/abs/1902.05554). Averaged in time, the energy injection is thus isotropic.
Note that these are the details of the "TNG model". There are many other SMBH feedback models in the AREPO code. (RAMSES is a code, not a model).
Lee JinHyung
8 Apr
Sorry, it was the reference for the NewHorizon simulation; it was written in a hurry.
And yes, I was asking about the model used in the TNG.
Thank you for your fast response!
Hello, I'm recently interested in the kinetic feedback mechanism of SMBH in the TNG simulation.
If I understand it correctly, according to Weinberger et al. (2017), for each feedback event, a random gas cell is chosen, and the distance-weighted momentum is applied in a random direction. However, I couldn't find any information about the function of smoothing kernel w(r) and the random injection unit vector n.
Thanks for your help!
edit:
I found another thread about the kinetic mode.
Still, I want to verify my understanding of the mechanism of the TNG since other simulations, such as the RAMSES, use the preferred direction to shoot the mass and momentum.
(1) A single random gas cell is not chosen. Instead, momentum is given to all N nearest gas cells (N=256 for TNG100-1).
(2) Yes the kernel shape is the usual cubic spline, that depends only on distance.
(3) Yes the direction vector -for each event- is entirely random. So there are no preferred directions, and energy is not injected in a bipolar geometry (although outflows can then naturally emerge as bipolar, see e.g. https://arxiv.org/abs/1902.05554). Averaged in time, the energy injection is thus isotropic.
Note that these are the details of the "TNG model". There are many other SMBH feedback models in the AREPO code. (RAMSES is a code, not a model).
Sorry, it was the reference for the NewHorizon simulation; it was written in a hurry.
And yes, I was asking about the model used in the TNG.
Thank you for your fast response!