Hi Nelson!
I have two questions that I would like to ask for your advice on:
Is it possible for a subhalo's merger tree main branch to have discontinuities, such as appearing in snapshots 99 and 97 but temporarily "disappearing" in snapshot 98? Or even more extreme cases, such as appearing in snapshots 99 and 90 with a longer period of absence in between?
Is there a simple method to quickly determine if a subhalo remains central (i.e., always the first subhalo of its halo) over a range of snapshots (e.g., from 99 to 90)? Additionally, is it possible for a subhalo to change from being central to becoming a satellite and then revert back to being central again?
Thank you for your help.
Best regards，
张
Dylan Nelson
25 Sep
(1) For SubLink, the docs say "Sometimes the halo finder does not detect a small subhalo that is passing through a larger structure, because the density contrast is not high enough. SubLink deals with this issue by allowing some subhalos to skip a snapshot when finding a descendant." So, yes, definitely a tree can contain a subhalo at snapshot 99 and 97 but not 98. However, it is not possible to skip all the way from e.g. snapshot 99 to 90.
(2) A subhalo is a central if and only if GroupFirstSub[SubhaloGrNr[i]] == i. You just need to check this condition.
(3) A subhalo can definitely switch between being a central and satellite several times, especially during a complex or near equal mass merger I would expect this.
Hi Nelson!
I have two questions that I would like to ask for your advice on:
Is it possible for a subhalo's merger tree main branch to have discontinuities, such as appearing in snapshots 99 and 97 but temporarily "disappearing" in snapshot 98? Or even more extreme cases, such as appearing in snapshots 99 and 90 with a longer period of absence in between?
Is there a simple method to quickly determine if a subhalo remains central (i.e., always the first subhalo of its halo) over a range of snapshots (e.g., from 99 to 90)? Additionally, is it possible for a subhalo to change from being central to becoming a satellite and then revert back to being central again?
Thank you for your help.
Best regards，
张
(1) For SubLink, the docs say "Sometimes the halo finder does not detect a small subhalo that is passing through a larger structure, because the density contrast is not high enough. SubLink deals with this issue by allowing some subhalos to skip a snapshot when finding a descendant." So, yes, definitely a tree can contain a subhalo at snapshot 99 and 97 but not 98. However, it is not possible to skip all the way from e.g. snapshot 99 to 90.
(2) A subhalo is a central if and only if
GroupFirstSub[SubhaloGrNr[i]] == i. You just need to check this condition.(3) A subhalo can definitely switch between being a central and satellite several times, especially during a complex or near equal mass merger I would expect this.