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pynbody / genetIC

The GM initial conditions generator
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Photogenic file for tipsy output #58

Closed Martin-Rey closed 5 years ago

Martin-Rey commented 5 years ago

Hi Andrew,

I have encountered a question from @mtremmel relating to how genetIC produces the photogenic file for tipsy.

Currently, the particles flagged and outputted into the photogenic iords are chosen as the one with the lowest mass in the zoom simulation:
https://github.com/ucl-cosmoparticles/genetIC/blob/cb399aca2b15780274acc82fc1a2a5764c5277f2/genetIC/src/io/tipsy.hpp#L130-L136

In the case of baryon runs, zoomed gas particles have slightly lower mass than zoomed DM, such that only gas is contained in the photogenic file. Michael would have expected to rather have only DM iords as the normal behaviour.

Is the current behaviour what was anticipated when coding this functionality? Has tracking the gas rather than DM led to problems in your previous use of genetIC+photogenic+gasoline?

Martin

apontzen commented 5 years ago

It’s never caused me a problem. But of course if it poses a problem one could use a dump_id to get IDs for whichever dark matter particles you like, then use those instead of the default photogenic.txt output.