Actually yes. You could check this yourself by examining the last column in HopAnalysis out. If max_r < 2*(1/512)=3.9e-3 then yes, it will skip it. In one of my simulations, a 5e11 Msun halo has a max_r of 2.64e-03 corresponding to 168 kpc/h. The halo profiler was not built for profiling halos with < 2 cells in radius. In my mind you have at least four options:
Hi Sam,
Here is how I am using it right now...
virial_filters=[['TotalMassMsun','>=','5e11']],
hp.add_halo_filter(HP.VirialFilter,must_be_virialized=True,
overdensity_field='ActualOverdensity',
virial_overdensity=200,
virial_quantities=['TotalMassMsun','RadiusMpc'])
hp.make_profiles(filename="VirialHaloes.out")
And i get 500.
Do you think it has something to do with the grid spacing (for 512 ^3 grid in 200 Box, it is 390 Kpc)
HaloProfiler may be skipping small halos completely since they are smaller than 390 Kpc.
Shankar
-----Original Message-----
From: yt-users-bounces@lists.spacepope.org on behalf of Sam Skillman
Sent: Sun 2/28/2010 12:34 PM
To: Discussion of the yt analysis package
Subject: Re: [yt-users] Dealing with HOP groups
Hi Shankar,
Do you have a line that looks like:
hp.add_halo_filter(HP.VirialFilter,must_be_virialized=True,
overdensity_field='ActualOverdensity',
virial_overdensity=200,
virial_filters=[['TotalMassMsun','>=','1e14']],
virial_quantities=['TotalMassMsun','RadiusMpc'])
If so, please post it. The number of halos > 10^14 Msun is fairly close to
500 in a 200 Mpc box. If you want the halo profiler to use all halos, set
virial_filters=[['TotalMassMsun','>=','1e14']] accordingly.
Sam
On Sun, Feb 28, 2010 at 11:08 AM, Agarwal, Shankar <sagarwal@ku.edu> wrote:
> Hi Stephen,
>
> I read
> http://lists.spacepope.org/pipermail/yt-users-spacepope.org/2009-March/000110.html
>
> Do you remember the cosmology parameters for your run: particles, grid,
> box, refinement, AMR ON or OFF ?
>
>
> I have run a 200 Mpc/h box, 512^3 particle, 512^3 grid, AMR-OFF simulation
> and I get about 30,000 halos using HOP. When I try to finding virial halos,
> I get only 500. I may have to increase the grid to 1024^3.
>
> Let me know how you got 40,000 virial halos.
>
> Thanks
> Shankar
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>
--
Samuel W. Skillman
DOE Computational Science Graduate Fellow
Center for Astrophysics and Space Astronomy
University of Colorado at Boulder
samuel.skillman[at]colorado.edu
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