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pelahi / VELOCIraptor-STF

Galaxy/(sub)Halo finder for N-body simulations
MIT License
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Missing property from documentation: Parent_halo_ID #61

Closed VictorForouhar closed 4 years ago

VictorForouhar commented 4 years ago

In the VELOCIraptor's (v1.51) .catalog_groups output file, there is a property named Parent_halo_ID, but I have not managed to find any information or mention of it in the documentation.

I checked whether it was the same as the hostHaloID property contained in the output .properties, but they are different.

VictorForouhar commented 4 years ago

I think I figured out what information Parent_halo_ID contains. Whereas hostHaloID points to the top level, field halo (structureType == 10) that a group is bound to, the property Parent_halo_ID points to the halo (not necessarily structureType == 10) a group is part of as substructure, allowing you to determine the group hierarchy. Is this correct?

In either case, I still think it would be useful to mention this in the documentation.

pelahi commented 4 years ago

Correct, this field contains the information to the full substructure hierarchy, indicating an objects immediate parent. I will update the documentation.

MatthieuSchaller commented 4 years ago

@VictorForouhar how about the other aspects you were wondering about? Have these yet been clarified?

VictorForouhar commented 4 years ago

@MatthieuSchaller In regards to the results I was getting with VELOCIraptor, I still haven't run some of the tests I had in mind, as COSMA is down for maintenance at the moment.

Once I get the chance, I would want to run another halo finder and see whether I get the same results as with VELOCIraptor. If I do, this might mean it has something to do with the data I am using and not an issue with VELOCIraptor itself (which I want to confirm before potentially flagging an issue).

MatthieuSchaller commented 4 years ago

Keep in mind that all the halo finders have different definitions of what a 'halo' is and diverge even more in terms of their definition of what a sub-halo is. See https://ui.adsabs.harvard.edu/abs/2012MNRAS.423.1200O/abstract