In the halo list provided by TNG, is there any information about whether a halo is relaxed or un-relaxed? Or based on what halo properties can we identify whether a halo is relaxed or un-relaxed?
I am looking forward to your reply. Thank you.
Daozhou Wang
11 Dec
I saw a paper defining Relaxed halos: Δ<0.07r_200c; Unrelaxed halos: :Δ>0.07r_200c, where Δ=||r_min-r_com||, where r_min is the position of the particle with the minimal gravitational potential, and r_com is the centre of mass of all dark matter particles within r200c. Are these two quantities the GroupPos and GroupCM of the TNG simulation field?
The paper is as follows: Wang K, Mo H J, Chen Y, et al. An efficient and robust method to estimate halo concentration based on the method of moments[J]. Monthly Notices of the Royal Astronomical Society, 2024, 527(4): 10760-10776.
Dylan Nelson
16 Dec
There are many different ways to define relaxedness, including this spatial offset. This could be computed as you say, using GroupPos versus GroupCM. Another option is the ratio of the mass of the central subhalo to the total halo, or of the second most massive galaxy to the most massive.
There are no relaxedness values in the catalogs, so you should compute one yourself.
Hi, Dylan!
In the halo list provided by TNG, is there any information about whether a halo is relaxed or un-relaxed? Or based on what halo properties can we identify whether a halo is relaxed or un-relaxed?
I am looking forward to your reply. Thank you.
I saw a paper defining Relaxed halos: Δ<0.07r_200c; Unrelaxed halos: :Δ>0.07r_200c, where Δ=||r_min-r_com||, where r_min is the position of the particle with the minimal gravitational potential, and r_com is the centre of mass of all dark matter particles within r200c. Are these two quantities the GroupPos and GroupCM of the TNG simulation field?
The paper is as follows: Wang K, Mo H J, Chen Y, et al. An efficient and robust method to estimate halo concentration based on the method of moments[J]. Monthly Notices of the Royal Astronomical Society, 2024, 527(4): 10760-10776.
There are many different ways to define relaxedness, including this spatial offset. This could be computed as you say, using GroupPos versus GroupCM. Another option is the ratio of the mass of the central subhalo to the total halo, or of the second most massive galaxy to the most massive.
There are no relaxedness values in the catalogs, so you should compute one yourself.
Thank you for your reply, thank you very much!