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zhafen / linefinder

A tool for finding and classifying the worldlines of Lagrangian parcels of mass, in the context of hydrodynamic simulations of galaxy formation.
https://zhafen.github.io/linefinder
MIT License
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A significant fraction of stars are classified as intergalactic transfer #55

Closed zhafen closed 6 years ago

zhafen commented 6 years ago

Originally reported by Zachary Hafen (Bitbucket: zhafen, GitHub: zhafen)

t_res_during_t_m_cdf_stars.png

The above image shows the CDF of externally-processed particles that were stars the snapshot before they first accreted. This is for particles in m12i. As can be seen, in any given case a lot of stars are classified as intergalactic transfer (the value of the cdf at the dividing line indicates the fraction classified as intergalactic transfer). This is not a good thing.

Relevant Questions:

  1. How deep does this problem run? Is it in Daniel's data products? It's at least in FIRE-1 m12i of Daniel's data.
  2. If I go back a snapshot or two earlier (i.e. not just the snapshot before accreting) is this still a major issue? It is still an issue.
  3. Is this sensitive to radial cut?
  4. Is this related to Issue #40?
  5. Are our minimum criteria constraints too strong?
zhafen commented 6 years ago

Original comment by Zachary Hafen (Bitbucket: zhafen, GitHub: zhafen)

We still need to decide on an official galaxy definition, but I'm closing this issue since we now know what's happening.

In particular, our previous galaxy was just too small.

zhafen commented 6 years ago

Original comment by Zachary Hafen (Bitbucket: zhafen, GitHub: zhafen)

Next I need to try implementing an additional inside galaxy criterion.

zhafen commented 6 years ago

Original comment by Zachary Hafen (Bitbucket: zhafen, GitHub: zhafen)

Updated potential causes.

zhafen commented 6 years ago

Original comment by Zachary Hafen (Bitbucket: zhafen, GitHub: zhafen)

As one check, we would expect that the particles that were stars for a while prior to accreting should be classified similarly. Indeed they do: even when we select only particles that were stars 15 snapshots prior to first accreting onto the galaxy we see a significant fraction of those particles classified as intergalactic transfer or NEP. The fraction classified as NEP does go down a bit though.

zhafen commented 6 years ago

Original comment by Zachary Hafen (Bitbucket: zhafen, GitHub: zhafen)

This problem is also found in Daniel's data. However, at least in his data none of the stars are classified as pristine.

In my data a non-negligible fraction of stars are counted as pristine...

zhafen commented 6 years ago

Original comment by Zachary Hafen (Bitbucket: zhafen, GitHub: zhafen)

Daniel knows about this, and classifies it as stellar stripping. We should check if this is true by making some movies.

If it is true, then we need to manually classify it as such.