[yt-users] Halo positions in merger trees
Jean-Claude Waizmann
waizmann at ita.uni-heidelberg.de
Thu Aug 6 02:24:53 PDT 2009
Hi all,
I have the following problem, when I compare the results of a merger
tree created using fastBuildMerge.py for the most massive halo at z=0,
with the output of running hop manually, I get the following
discrepancy:
#part x y z
fastBuildMerge 33809 0.492 0.495 0.485
Hop(yt)manually 50931 0.5019 0.4981 0.4902
old enzohop 43815 0.5019 0.4981 0.4902
Visual inspection of slices show, that the last two positions are
correct. So I wonder why the merger_tree gives wrong values even though
it is calling the same Hop routine. I need the positions of the parent
halos for profiling, and a difference of 0.01 in position corresponds to
1.28 Mpc which is a lot for a galaxy cluster, and would spoil the
analysis.
The difference in mass between the first two is strange as well. Did
anybody encounter the same problem and/or knows where it is coming from?
Thanks!
Jean-Claude
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