Galaxy Merger History in TNG50 MWs (SubfindIDAtFormation)
TIANCHENG SUN
26 Mar
Hi Dr. Nelson,
I have recently downloaded the galaxy data (414917) from the MW/M31 Cutout Data and am currently investigating the merger history of this galaxy, with a particular focus on its main mergers. Using the SubfindIDAtFormation, I have identified three significant mergers. However, I am uncertain whether these mergers originate from the same dwarf galaxy.
I also downloaded the corresponding sublinkgal file for 414917. However, I noticed that the SubhaloID values in the sublinkgal file do not seem to match the SubfindIDAtFormation values, making it difficult to establish a one-to-one correspondence.
Could you kindly advise me on how to trace the dwarf galaxies that merged into 414917? Any guidance on how to resolve the discrepancy between the SubhaloID and SubfindIDAtFormation would be greatly appreciated.
Thank you for your time and assistance.
Best,
Tiancheng Sun，
National Astronomical Observatories, Chinese Academy of Sciences
Dylan Nelson
26 Mar
The SubfindIDAtFormation is for individual star particles. And you need also to use the SnapNumAtFormation.
The combination of these two numbers tells you, for a single star particle, when and where it was born.
This could be used to analyze the ex-situ stellar component, but identifying mergers in this way doesn't seem the most straightforward approach.
To identify mergers, I would instead look directly at the merger trees. You can search the tree, either SubLink or SubLink_gal, for all mergers with a given stellar mass ratio, for example.
Hi Dr. Nelson,
I have recently downloaded the galaxy data (414917) from the MW/M31 Cutout Data and am currently investigating the merger history of this galaxy, with a particular focus on its main mergers. Using the SubfindIDAtFormation, I have identified three significant mergers. However, I am uncertain whether these mergers originate from the same dwarf galaxy.
I also downloaded the corresponding sublinkgal file for 414917. However, I noticed that the SubhaloID values in the sublinkgal file do not seem to match the SubfindIDAtFormation values, making it difficult to establish a one-to-one correspondence.
Could you kindly advise me on how to trace the dwarf galaxies that merged into 414917? Any guidance on how to resolve the discrepancy between the SubhaloID and SubfindIDAtFormation would be greatly appreciated.
Thank you for your time and assistance.
Best,
Tiancheng Sun，
National Astronomical Observatories, Chinese Academy of Sciences
The
SubfindIDAtFormationis for individual star particles. And you need also to use theSnapNumAtFormation.The combination of these two numbers tells you, for a single star particle, when and where it was born.
This could be used to analyze the ex-situ stellar component, but identifying mergers in this way doesn't seem the most straightforward approach.
To identify mergers, I would instead look directly at the merger trees. You can search the tree, either SubLink or SubLink_gal, for all mergers with a given stellar mass ratio, for example.