Introduction

These files are the BlueTides Friend-of-friend (FOF) Catalogue.

For brieviaty, we include only the following particle types:

• 4 : Star particles
• 5 : Blackhole Particles
• FOFGroups : FOF groups

0 (Gas) and 1(Dark Matter) are not included.

The container format of these files is BigFile, which was developed for massively parallel IO of BlueTides on BlueWaters. See install for installation.

Redshifts

Here is a list of included redshift and the file size. The entire directory can be mirrored with lftp or curl.

Units

Units are in MP-Gadget internal units :

• Distance : h^− 1 Kpc
• Velocity : a^− 1⋅ km ⁄ s
• Mass : 10¹⁰h^− 1M_⊙

Useful Constants in this unit:

• Gravity Constant G = 47003.1
• Hubble Constant H = 0.1
• Speed of light C = 3 × 10⁵

Columns

In bigfile a column is represented by a BigBlock. Common blocks are

1. For particles

4/Mass, 4/Position, 4/Velocity,
5/Mass, 5/Position, 5/Velocity,
4/StarFormationTime,
5/BlackholeMass, 5/BlackholeAccretionRate

2. For FOFGroup

FOFGroups/OffsetByType
FOFGroups/LengthByType
FOFGroups/MassByType
FOFGroups/Mass
FOFGroups/StarFormationRate
FOFGroups/BlackholeAccretionRate
FOFGroups/MassCenterPosition
FOFGroups/MassCenterVelocity

Install

To install bigfile, clone the repository and use standard python setup.py.

git clone https://github.com/rainwoodman/bigfile
(cd bigfile; python setup.py install --user)

Example

Once a bigfile is opened, access it is similar to a numpy structure array, except slicing is always required (similar to pyfits or h5py). In other words, to read from the file, use block[start:end], where start and end are the start and end offsets of the range to be read.

The jump table for accessing the corresponding particle attributes of a halo are stored in FOFGroups/LengthByType and FOFGroups/OffsetByType.

python
>>> from bigfile import BigFile
>>> p037 = BigFile('PIG_037')
>>> print p037['header'].attrs.keys
['BoxSize', 'HubbleParam', 'MassTable', 'NumFOFGroupsTotal',
        'NumPartInGroupTotal', 'Omega0', 'OmegaLambda', 'Time']
>>> print p037['header'].attrs['Time'][0]
0.0666666663633
>>> print p037.blocks

>>> print p037['FOFGroups/Mass'].size
5332371
>>> print p037['FOFGroups/MassByType'][:1]
[[ 0.96118915  4.94944572  0.          0.          0.00673234  0.    ]]
>>> sel = slice(p037['FOFGroups/OffsetByType'][0][4],
        p037['FOFGroups/OffsetByType'][0][4] + p037['FOFGroups/LengthByType'][0][4])
>>> print p037['4/Mass'][sel].sum()
0.00673234
>>> print p037['FOFGroups/MassByType'][0][4]
0.00673234

Issues

There shall be many issues. Please file a bug report at

https://github.com/bluetides-project/bluetides-datarelease/issues/new