My code uses TNG50 to pull descendants from a subhalo at z=2, grab their Halpha maps as hdf5s from the visualiser and then apply some transformations on them. This works fine the majority of the time but I occasionally come across a subhalo that has descendants, but all blank visualisations. I can tell because my output after rotation is the same, when it shouldn't be. When I check the visualiser for these specific subhalo descendants, they are indeed blank.
My code can deal with it and just continues but I would be interested in understanding why this happens?
Thanks
Raman
Dylan Nelson
7 Nov '21
Dear Raman,
Do you mean that some specific (snapshot,subhalo ID) combinations return Halpha maps which are blank? Can you provide a specific example?
Raman Sharma
7 Nov '21
Thanks Dylan, yep if you look at the subfindIDs of all the descendants of subfindID 5 in snapnum=33 in TNG50-1, they are all blank images. So for example the final descendant is subfindID 41 in snapnum 99 and that is blank. At snapnum 50 the ID is 25252 and that again is blank. Its the same for all of the descendants of that subhalo.
Am I missing something? I haven't identified all of the ones that don't work
Raman
Dylan Nelson
8 Nov '21
Hi Raman,
in TNG50-1 at snap 99, subhalo 41 has no gas (it does have DM and stars), so indeed the total H-alpha emission should be zero, and the map would be blank. This isn't unexpected: this is a satellite galaxy, and its gas could have been removed via stripping by this point in time.
Raman Sharma
8 Nov '21
Aah yes, thanks Dylan yep that makes perfect sense.
Hello,
My code uses TNG50 to pull descendants from a subhalo at z=2, grab their Halpha maps as hdf5s from the visualiser and then apply some transformations on them. This works fine the majority of the time but I occasionally come across a subhalo that has descendants, but all blank visualisations. I can tell because my output after rotation is the same, when it shouldn't be. When I check the visualiser for these specific subhalo descendants, they are indeed blank.
My code can deal with it and just continues but I would be interested in understanding why this happens?
Thanks
Raman
Dear Raman,
Do you mean that some specific (snapshot,subhalo ID) combinations return Halpha maps which are blank? Can you provide a specific example?
Thanks Dylan, yep if you look at the subfindIDs of all the descendants of subfindID 5 in snapnum=33 in TNG50-1, they are all blank images. So for example the final descendant is subfindID 41 in snapnum 99 and that is blank. At snapnum 50 the ID is 25252 and that again is blank. Its the same for all of the descendants of that subhalo.
Am I missing something? I haven't identified all of the ones that don't work
Raman
Hi Raman,
in TNG50-1 at snap 99, subhalo 41 has no gas (it does have DM and stars), so indeed the total H-alpha emission should be zero, and the map would be blank. This isn't unexpected: this is a satellite galaxy, and its gas could have been removed via stripping by this point in time.
Aah yes, thanks Dylan yep that makes perfect sense.