Unit Length in the 'SubhaloPos' field for the Subbox Subhalo List Catalog
Austin Fraley
29 Jul '23
Hi all,
I am trying to work with the Subbox Subhalo List catalog to make plots of potential merger events within the subbox volume. I am confused about the units of the 'SubhaloPos' field because the numbers appear to be too large to be in the standard cMpc/h. Can somebody explain the meaning of this field in this particular catalog?
Dylan Nelson
30 Jul '23
Hi Austin,
The SubhaloPos is in the usual code units (ckpc/h). These positions are interpolated/extrapolated, so there is the possibility that they go outside the box e.g. at the very beginnings of trees. You would probably disregard any such times anyways (e.g. the corresponding subhalos are likely very low mass, or at high redshift).
I checked for TNG100-1 subbox0 and only 0.02% of positions are outside if [0,75000].
Hi all,
I am trying to work with the Subbox Subhalo List catalog to make plots of potential merger events within the subbox volume. I am confused about the units of the 'SubhaloPos' field because the numbers appear to be too large to be in the standard cMpc/h. Can somebody explain the meaning of this field in this particular catalog?
Hi Austin,
The
SubhaloPosis in the usual code units (ckpc/h). These positions are interpolated/extrapolated, so there is the possibility that they go outside the box e.g. at the very beginnings of trees. You would probably disregard any such times anyways (e.g. the corresponding subhalos are likely very low mass, or at high redshift).I checked for TNG100-1 subbox0 and only 0.02% of positions are outside if [0,75000].