[yt-users] halo mass function question

[Stephen Skory]

Robert,

>I'm running through different cookbook tutorials and I've ran into a snag when 
>trying to form the halo mass function. 
>(http://yt.enzotools.org/doc/howto/hmf_howto.html#hmf-howto)
>
>
>I can run the halo finder, but the halo profiler is where I run into the issue. 

> I've been unsuccessful with both N-body only and N-body+gas runs of different 
>sizes.  It seems that the filter the tutorial employs filters out all of my 
>halos and I get this for every halo:
>
>
>yt.lagos   ERROR      2010-08-04 12:34:35,198 Skipping halo with r_max / r_min = 
>
>0.153458.


What's happening is the halo profiler is refusing to analyze certain halos if 
their radius is too small when compared to the most refined grid cell size. If 
you think about it, it is meaningless to build a radial profile of something 
that exists in just one or two cells.

If you still want to try to make a Halo Mass Function (HMF), you can use the 
output of the halo finder directly in the HMF module. You'll use the output of 
the halo finder ("HopAnalysis.out") and you'll specify the column of that file 
that contains the mass (2nd, or "1" in Python enumeration).

Good luck!

 _______________________________________________________
sskory at physics.ucsd.edu           o__  Stephen Skory
http://physics.ucsd.edu/~sskory/ _.>/ _Graduate Student
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