Parameters

I/O

Property	Description
`SnapshotPath`	Path to the files containing the particle information.
`HaloPath`	Path to the files containing information used to reconstruct the FoF group membership of particles.
`SnapshotFileBase`	Base name for the snapshot files, e.g. `<SnapshotFileBase>_<snap_nr>`.
`SnapshotDirBase`	Base name for the directories where snapshot subfiles are saved, if applicable. If there is only one file per snapshot, omit this option.
`SubhaloPath`	Base directory of where the HBT catalogues will be saved.
`MinSnapshotIndex`	The minimum output number of the simulation being analysed.
`MaxSnapshotIndex`	The maximum output number of the simulation being analysed.
`SnapshotIdList`	Which subset of snapshots to analyse, if applicable. For example, if we only want to analyse every second snapshot of a ten snapshot run: 1 3 5 7 9..

Property	Description
`SnapshotFormat`	The format used by files containing the particle information.
`GroupFileFormat`	The format used by the files containing the FoF memberships of particles.
`ParticleNullGroupId`	The value in the FoF particle membership catalogue that corresponds to belonging to no FoF group.
`ParticlesSplit`	If particles split in the simulation, in which case their splitting history needs to be provided. Only currently implemented for SWIFT hydrodynamical simulations
`SaveBoundParticleProperties`	If the position, velocity, mass and type of particles bound to subhaloes should be saved alongside the subhalo catalogues. It also includes thermal energy if thermal unbinding is enabled.
`SaveBoundParticleBindingEnergies`	If the internally calculated binding energies of particles bound to subhaloes should be saved alongside the subhalo catalogues.

0

The unit system used by the simulation and used in the outputs. For Swift outputs, they are set using the snapshot metadata.

Property	Description
`MassInMsunh`	Mass of particles in units of Msun / h.
`LengthInMpch`	Lengths in units of Mpc / h.
`VelInKmS`	Velocity in units of km / s.

Property	Description
`PeriodicBoundaryOn`	Whether the box is periodic.
`BoxSize`	Side length of each side of the box. Only cubes are supported.

Property	Description
`TreeNodeOpenAngle`	Geometric criteria to determine whether a tree node should be opened or can be used as is.
`TreeAllocFactor`	The maximum number of cells used in the gravity tree, relative to the number of particles.
`TreeMinNumOfCells`	Minimum number of tree cells to use.

Property	Description
`SofteningHalo`	The comoving gravitational softening value. Assumed to be the same for all particle types.
`MaxPhysicalSofteningHalo`	The maximum physical gravitational softening value. Assumed to be the same for all particle types.

Property	Description
`BoundMassPrecision`	Convergence threshold of the fractional difference in the number of bound particles between unbinding iterations.
`SourceSubRelaxFactor`	How many particles a subhalo can have associated to its source subhalo, relative to its number of bound particles.
`MaxSampleSizeOfPotentialEstimate`	Maximum number of particles used to estimate the gravitational potential of particles. If the subhalo has more than this value, a randomly selected `MaxSampleSizeOfPotentialEstimate` particles are used as gravity sources.
`RefineMostBoundParticle`	If the self-binding energy of the most bound subset of particles should be computed after unbinding the subhalo. This step is done to better identify the most bound particle if potential subsampling was enabled.
`BoundFractionCenterRefinement`	Fraction of the most bound particles whose self-binding energies are computed to better estimate the most bound particle. The actual value is `max(MaxSampleSizeOfPotentialEstimate, BoundFractionCenterRefinement)`

Property	Description
`TracerParticleTypes`	Particle types that can be used as subhalo tracers. Tracers are used to identify which FoF group hosts a given subhalo, the offsets in phase-space between subhaloes, and the position/velocity of orphan (disrupted) subhaloes. We recommend using time-persistent, collisionless particles (e.g. DM & stars).
`MinNumPartOfSub`	Minimum number of bound particles required for a subhalo to be resolved, regardless of their particle type.
`NumTracerHostFinding`	How many tracer particles are used to identify the host FoF group of subhaloes. The weighting of each particle reflects their binding energy ordering in the previous output.
`NumTracersForDescendants`	How many tracer particles are used to identify which subhalo has accreted the core of subhaloes that have disrupted in the current snapshot.
`MergeTrappedSubhalos`	Whether to manually merge resolved subhaloes that overlap in phase-space. Recommended to always leave on.
`MajorProgenitorMassRatio`	The threshold used to identify which subhaloes are central candidates within a FoF. Expressed relative to the most massive subhalo in said host FoF group.

Property	Description
`SnapshotHasIdBlock`	Whether particles are already sorted by Particle IDs, and hence no ParticleID dataset is specified within the snapshot file.
`ParticleIdNeedHash`	Whether to create a hash map to retrieve particle properties given an ID type.
`GroupParticleIdMask`	Hexadecimal mask indicating which digits of the particle IDs are significant. For example, if only the first 4 digits are required (i.e. "1111" in binary), then this would correspond to "F". Only required for peculiar Gadget formats.
`SnapshotIdUnsigned`	If the particle IDs are saved as an unsigned integer.