Just a naive question. I'm trying to quantify the baryonic effects on WL statistics. But what confuse me a lot is the mass of blackhole. From the TNG snapshot, I found two different ‘mass’ for BH particles, the ‘BH_Mass’ and ‘Masses’. In my opinion, I should use the 'Masses' of blackhole, which includes the gas reservoir, to do the multiple-lens-plane ray-tracing. However, the ‘Masses’ of blackhole is too big, where the maximum is greater than 10^14 M⊙/h and over my head. If I do raytracing this way the result is strange. There are large difference between my power spectrum with others. So my question is that whether I should use the BH_Mass to represent the mass of the BH particles in snapshot when I do the raytracing?

Thanks a lot in advance,

Dylan Nelson

28 Oct '21

Dear Zhao An,

I admit I am not entirely sure where SMBH mass comes into WL statistics - everywhere except in the very central kpc of galaxy nuclei, the SMBH mass is negligible compared to other components.

That said, the maximum (z=0) value of PartType5/Masses for TNG100-1 is 10^10.1 Msun, and for TNG300-1 is 10^11.0 Msun. So if you obtained a value of 10^14, perhaps double-check the involved unit conversions.

I would suggest plotting PartType5/Masses versus halo mass, and PartType5/BH_Mass versus halo mass, to get an intuitive sense of how these two differ. While the "actual" SMBH mass is given by BH_Mass, i.e. for comparison against a BH mass function or M_BH-M* relation, the Masses gives the total dynamical mass of the particle, which may be better for a lensing calculation. But the difference should be always small for SMBHs which are not near the seed mass.

ZHAO AN

29 Oct '21

Hi Dylan

Thanks a lot for your reply and I will check the unit conversion in my code.

ZHAO AN

30 Oct '21

I check the unit of blackhole with your code, the illustris_python, but result remains the same. The snapshot I use is from TNG300-3, and the redshif z=0. In the figure we can see that the maximum of blackhole 'Masses' is 22679.809, in units of 10^10 Msun which I found in the Data Specifications. I wonder what went wrong and look forward to your reply.

Dylan Nelson

30 Oct '21

Yes that's correct, in TNG300-3 the maximum BH mass is 10^14.5. I agree this is unphysically high, and you wouldn't want to include it.

Ideally you would use TNG300-1 for your calculations. The resolution of TNG300-3 is so poor that we would, in practice, never use it for science.

ZHAO AN

30 Oct '21

Oh! I see. I'm going to choose higher resolution snapshots later. Thanks al ot for your answer.

Hi,

Just a naive question. I'm trying to quantify the baryonic effects on WL statistics. But what confuse me a lot is the mass of blackhole. From the TNG snapshot, I found two different ‘mass’ for BH particles, the ‘BH_Mass’ and ‘Masses’. In my opinion, I should use the 'Masses' of blackhole, which includes the gas reservoir, to do the multiple-lens-plane ray-tracing. However, the ‘Masses’ of blackhole is too big, where the maximum is greater than 10^14 M⊙/h and over my head. If I do raytracing this way the result is strange. There are large difference between my power spectrum with others. So my question is that whether I should use the BH_Mass to represent the mass of the BH particles in snapshot when I do the raytracing?

Thanks a lot in advance,

Dear Zhao An,

I admit I am not entirely sure where SMBH mass comes into WL statistics - everywhere except in the very central kpc of galaxy nuclei, the SMBH mass is negligible compared to other components.

That said, the maximum (z=0) value of

`PartType5/Masses`

for TNG100-1 is 10^10.1 Msun, and for TNG300-1 is 10^11.0 Msun. So if you obtained a value of 10^14, perhaps double-check the involved unit conversions.I would suggest plotting

`PartType5/Masses`

versus halo mass, and`PartType5/BH_Mass`

versus halo mass, to get an intuitive sense of how these two differ. While the "actual" SMBH mass is given by`BH_Mass`

, i.e. for comparison against a BH mass function or M_BH-M* relation, the`Masses`

gives the total dynamical mass of the particle, which may be better for a lensing calculation. But the difference should be always small for SMBHs which are not near the seed mass.Hi Dylan

Thanks a lot for your reply and I will check the unit conversion in my code.

I check the unit of blackhole with your code, the illustris_python, but result remains the same. The snapshot I use is from TNG300-3, and the redshif z=0. In the figure we can see that the maximum of blackhole 'Masses' is 22679.809, in units of 10^10 Msun which I found in the Data Specifications. I wonder what went wrong and look forward to your reply.

Yes that's correct, in TNG300-3 the maximum BH mass is 10^14.5. I agree this is unphysically high, and you wouldn't want to include it.

Ideally you would use TNG300-1 for your calculations. The resolution of TNG300-3 is so poor that we would, in practice, never use it for science.

Oh! I see. I'm going to choose higher resolution snapshots later. Thanks al ot for your answer.