Request about L-Galaxies Catalogue for the TNG 300
Arielz Zandivarez
19 Aug
I have a question about a particular dataset. In Data Access, Data Specifications, in Supplementary Data Catalogues, item (n), you describe the L-Galaxies Semi-Analytical model run on top of the TNG. My question is that the dataset provided with the semi-analytical galaxies does not include the "GalaxyID" parameter, which is usually available (for instance, in all the available Millennium SAMs) and very helpful for linking semi-analytical galaxies between different snapshots. Is there any chance that information could be added to this particular dataset?
I am sorry to bother you with this, and I understand if there is nothing you can do about this particular dataset.
Thanks
Ariel
Dylan Nelson
20 Aug
In this case, the way to link the galaxies between different snapshots is to use the TNG merger trees.
After selecting a halo, and loading its main progenitor branch (of the central subhalo), you can get the (evolving) SAM properties of that galaxy by following this branch.
Unfortunately yes I see this is a bit more work than if there was a unique "GalaxyID" label.
Arielz Zandivarez
20 Aug
Thanks so much for your response, Dylan.
I've already looked into the merger tree to extract the L-galaxies data for the TNG galaxies. However, this only allows us to compare the properties of the TNG hydrodynamical galaxies with their semi-analytic counterparts on an object-by-object basis. Unfortunately, this information is somewhat limited and doesn’t support more in-depth studies, like building a mock lightcone for all the semianalytic galaxies built on TNG dark matter only halos or examining the merger trees of those semianalytical galaxies to analyse their evolution. The issue is that several semianalytic galaxies don't have a corresponding hydrodynamical galaxy, and vice versa.
It would be great if each semianalytic galaxy could be linked across different simulation outputs. That's a bit frustrating because there are files with all the semi-analytic galaxies across various time outputs. Still, there’s no way to track each semianalytical galaxy over time—especially those without hydrodynamical counterparts—since there are no indices to do so.
I understand that the initial study that applied the semianalytical model to the TNG merger trees can be replicated with the data that is now available. Hence, it is understandable that not all the information needed for other types of analyses is necessarily accessible for this sample.
I have a question about a particular dataset. In Data Access, Data Specifications, in Supplementary Data Catalogues, item (n), you describe the L-Galaxies Semi-Analytical model run on top of the TNG. My question is that the dataset provided with the semi-analytical galaxies does not include the "GalaxyID" parameter, which is usually available (for instance, in all the available Millennium SAMs) and very helpful for linking semi-analytical galaxies between different snapshots. Is there any chance that information could be added to this particular dataset?
I am sorry to bother you with this, and I understand if there is nothing you can do about this particular dataset.
Thanks
Ariel
In this case, the way to link the galaxies between different snapshots is to use the TNG merger trees.
After selecting a halo, and loading its main progenitor branch (of the central subhalo), you can get the (evolving) SAM properties of that galaxy by following this branch.
Unfortunately yes I see this is a bit more work than if there was a unique "GalaxyID" label.
Thanks so much for your response, Dylan.
I've already looked into the merger tree to extract the L-galaxies data for the TNG galaxies. However, this only allows us to compare the properties of the TNG hydrodynamical galaxies with their semi-analytic counterparts on an object-by-object basis. Unfortunately, this information is somewhat limited and doesn’t support more in-depth studies, like building a mock lightcone for all the semianalytic galaxies built on TNG dark matter only halos or examining the merger trees of those semianalytical galaxies to analyse their evolution. The issue is that several semianalytic galaxies don't have a corresponding hydrodynamical galaxy, and vice versa.
It would be great if each semianalytic galaxy could be linked across different simulation outputs. That's a bit frustrating because there are files with all the semi-analytic galaxies across various time outputs. Still, there’s no way to track each semianalytical galaxy over time—especially those without hydrodynamical counterparts—since there are no indices to do so.
I understand that the initial study that applied the semianalytical model to the TNG merger trees can be replicated with the data that is now available. Hence, it is understandable that not all the information needed for other types of analyses is necessarily accessible for this sample.
Thanks again.
Ariel