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  • Volker Springel
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  • snapshotformat

snapshotformat · Changes

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Update snapshotformat authored Aug 08, 2019 by Rainer Weinberger's avatar Rainer Weinberger
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userguide/snapshotformat.md
View page @ bc4fae05
......@@ -17,96 +17,53 @@ script.
**Fields for the particle data output**
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Field name | Block ID | Units | Description |
+=============================+==============+================================================================================================================+=====================================================================================================================================+
| Coordinates | POS | :math:`\text{UnitLength}` :math:`a \, h^{-1}` | Comoving position; for cells: position of mesh-generating point |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Velocities | VEL | :math:`\text{UnitVelocity}` :math:`a^{0.5}` | Velcoity |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| ParticleIDs | ID | | Unique ID of particle |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Masses | MASS | :math:`\text{UnitMass}` :math:`h^{-1}` | Mass, if not present: header/MassTable |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Potential | POT | :math:`\text{UnitVelocity}^2` :math:`a^{-1}` | Gravitational potential energy (``OUTPUTPOTENTIAL``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| InternalEnergy | U | :math:`\text{UnitVelocity}^2` | Specific internal energy |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Density | RHO | :math:`\text{UnitMass}` :math:`\text{UnitLength}^{-3}` :math:`a^{-3} \, h^2` | Density of gas |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Pressure | PRES | :math:`\text{UnitLength}^{-3}` :math:`\text{UnitMass}^1` :math:`\text{UnitVelocity}^2` :math:`a^{-3} \, h^2` | Thermal pressure of gas (``OUTPUT_PRESSURE``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| SoundSpeed | CSND | :math:`\text{UnitVelocity}` | Effective sound speed of both thermal and magnetic component (note different `a` scaling compared to VEL!) (``OUTPUT_CSND``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| ElectronAbundance | NE | | Electron number density relative to hydrogen (``COOLING``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| NeutralHydrogenAbundance | NH | | Neutral hydrogen fraction (``COOLING``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| StarFormationRate | SFR | :math:`\text{Msun} \, \text{yr}^{-1}` | Star formation rate (``USE_SFR``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| VelocityDivergence | DIVV | :math:`\text{UnitVelocity}` :math:`\text{UnitLength}^{-1}` :math:`h` | Velocity divergence (``OUTPUT_DIVVEL``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| VelocityCurl | ROTV | :math:`\text{UnitVelocity}` :math:`\text{UnitLength}^{-1}` :math:`h` | Rotation of velocity (``OUTPUT_CURLVEL``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| CoolingHeatingEnergy | COHE | :math:`\text{UnitLength}^{-1}` :math:`\text{UnitVelocity}^3` :math:`\text{UnitMass}` | Actual cooling rate, differing from nominal coolnig rate in star forming cells (``OUTPUT_COOLHEAT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| SurfaceArea | AREA | :math:`\text{UnitLength}^2` :math:`a^2 \, h^{-2}` | Surface area of a Voronoi cell (``OUTPUT_SURFACE_AREA``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| NumFacesCell | NFAC | | Number of faces of a Voronoi cell (``OUTPUT_SURFACE_AREA``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| CoolingRate | COOR | :math:`\text{erg} \, \text{cm}^3 \, \text{s}^{-1}` | The cooling rate of a gas cell (e.g. Lambda_net/n_H^2). (``OUTPUTCOOLRATE``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Vorticity | VORT | :math:`\text{UnitVelocity}` :math:`\text{UnitLength}^{-1}` :math:`h` | Vorticity of a cell (``OUTPUT_VORTICITY``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| PressureGradient | GRAP | :math:`\text{UnitLength}^{-4}` :math:`\text{UnitMass}` :math:`\text{UnitVelocity}^2` :math:`a^{-4} \, h^3` | Gradient of the pressure (limited) (``OUTPUT_PRESSURE_GRADIENT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| DensityGradient | GRAR | :math:`\text{UnitLength}^{-4}` :math:`\text{UnitMass}` :math:`a^{-4} \, h^3` | Gradient of the density (limited) (``OUTPUT_DENSITY_GRADIENT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| VelocityGradient | GRAV | :math:`\text{UnitLength}^{-1}` :math:`\text{UnitVelocity}^1` :math:`h` | Gradient of the velocity (limited) (``OUTPUT_VELOCITY_GRADIENT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| BfieldGradient | GRAB | :math:`\text{UnitMass}^{0.5}` :math:`\text{UnitVel}` :math:`\text{UnitLength}^{-5/2}` :math:`h^2 \, a^{-3}` | Gradient of the magnetic field (limited) (``OUTPUT_BFIELD_GRADIENT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Volume | VOL | :math:`\text{UnitLength}^3` :math:`a^3 \, h^{-3}` | (comoving) volume of gas cell. Can be calculated by Masses / Density. (``OUTPUT_VOLUME``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| VertexVelocity | VEVE | :math:`\text{UnitVelocity}` :math:`a^1` | velocity of the mesh-generating point (``OUTPUT_VERTEX_VELOCITY``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| MaxFaceAngle | FACA | | Maximum face angle of cell, quantifies roundness (``OUTPUT_MESH_FACE_ANGLE``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| CenterOfMass | CMCE | :math:`\text{UnitLength}` :math:`a^1 \, h^{-1}` | Center of mass of cell. Generally not equal to position of mesh generating point ``POS`` (``OUTPUT_CENTER_OF_MASS``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| task | TASK | | MPI task this particle is at (``OUTPUT_TASK``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| TimebinHydro | TBH | | Time bin the cell is at (``OUTPUT_TIMEBIN_HYDRO``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| TimeStep | TSTP | :math:`\text{UnitLength}` :math:`\text{UnitVelocity}^{-1}` :math:`h^{-1}` | Timestep in code units (``OUTPUTTIMESTEP``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Acceleration | ACCE | :math:`\text{UnitVelocity}^2` :math:`\text{UnitLength}^{-1}` :math:`a^{-1} \, h` | Acceleration due to gravitational forces, including external potential; different a scaling than internally!(``OUTPUTACCELERATION``)|
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Softenings | SOFT | :math:`\text{UnitLength}` :math:`a \, h^{-1}` | Gravitational softening length of particle/cell (``OUTPUT_SOFTENINGS``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| GravityInteractions | GINT | | Number of foce calculations in tree (``OUTPUTGRAVINTERACTIONS``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| MagneticField | BFLD | :math:`\text{UnitLength}^{-1.5}` :math:`\text{UnitMass}^{0.5}` :math:`\text{UnitVel}` :math:`h \, a^{-2}` | Magnetic field (in code units but Gauss system; note that internally, the Heaviside-Lorentz system is used) (``MHD``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| MagneticFieldDivergence | DIVB | :math:`\text{UnitLength}^{-2.5}` :math:`\text{UnitMass}^{0.5}` :math:`\text{UnitVel}` :math:`h^2 \, a^{-3}` | Divergence of magnetic field (``MHD``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| PassiveScalars | PASS | | Mass fraction of passive scalar quantity in cell (``PASSIVE_SCALARS``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| SubfindDensity | SFDE | :math:`\text{UnitLength}^{-3}` :math:`\text{UnitMass}` :math:`a^{-3} \, h^2` | density around particle (SPH like estimate) (``SAVE_HSML_IN_SNAPSHOT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| SubfindDMDensity | SFDD | :math:`\text{UnitLength}^{-3}` :math:`\text{UnitMass}` :math:`a^{-3} \, h^2` | dark matter density around particle (SPH like estimate) (``SAVE_HSML_IN_SNAPSHOT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| SubfindHsml | SFHS | :math:`\text{UnitLength}` :math:`a \, h^{-1}` | SPH smoothing length for density estimate (``SAVE_HSML_IN_SNAPSHOT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| SubfindVelDisp | SFVD | :math:`\text{UnitVelocity}` | SPH avaraged velocity dispersion around particle (``SAVE_HSML_IN_SNAPSHOT``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| GroupNr | GROU | | Number of nearest group (``FOF_FUZZ_SORT_BY_NEAREST_GROUP=1``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| HighResGasMass | HRGM | :math:`\text{UnitMass}` :math:`h^{-1}` | Conserved scalar quantity flaging the high-res region of a cosmological zoom simulation (``REFINEMENT_HIGH_RES_GAS``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| AllowRefinement | REF | | Is refinement allowed in gas cell. 0 for low-resolution region gas cells in zoom simulations (``REFINEMENT_HIGH_RES_GAS``) |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Field name | Block ID | Units | Description |
|-----------------------------|:-------------|----------------------------:|--------------------------------------:|
| Coordinates | POS | $`\text{UnitLength}`$ $`a\, h^{-1}`$ | Comoving position; for cells: position of mesh-generating point |
| Velocities | VEL | $`\text{UnitVelocity}`$ $`a^{0.5}`$ | Velcoity |
| ParticleIDs | ID | | Unique ID of particle |
| Masses | MASS | $`\text{UnitMass}`$ $`h^{-1}`$ | Mass, if not present: header/MassTable |
| Potential | POT | $`\text{UnitVelocity}^2`$ $`a^{-1}`$ | Gravitational potential energy (``OUTPUTPOTENTIAL``) |
| InternalEnergy | U | $`\text{UnitVelocity}^2`$ | Specific internal energy |
| Density | RHO | $`\text{UnitMass}`$ $`\text{UnitLength}^{-3}`$ $`a^{-3} \, h^2`$ | Density of gas |
| Pressure | PRES | $`\text{UnitLength}^{-3}`$ $`\text{UnitMass}`$ $`\text{UnitVelocity}^2`$ $`a^{-3} \, h^2`$ | Thermal pressure of gas (``OUTPUT_PRESSURE``) |
| SoundSpeed | CSND | $`\text{UnitVelocity}`$ | Effective sound speed of both thermal and magnetic component (note different `a` scaling compared to VEL!) (``OUTPUT_CSND``) |
| ElectronAbundance | NE | | Electron number density relative to hydrogen (``COOLING``) |
| NeutralHydrogenAbundance | NH | | Neutral hydrogen fraction (``COOLING``) |
| StarFormationRate | SFR | $`M_\odot`$ yr$`^{-1}`$ | Star formation rate (``USE_SFR``) |
| VelocityDivergence | DIVV | $`\text{UnitVelocity}`$ $`\text{UnitLength}^{-1}`$ $`h`$ | Velocity divergence (``OUTPUT_DIVVEL``) |
| VelocityCurl | ROTV | $`\text{UnitVelocity}`$ $`\text{UnitLength}^{-1}`$ $`h`$ | Rotation of velocity (``OUTPUT_CURLVEL``) |
| CoolingHeatingEnergy | COHE | $`\text{UnitLength}^{-1}`$ $`\text{UnitVelocity}^3`$ $`\text{UnitMass}`$ | Actual cooling rate, differing from nominal coolnig rate in star forming cells (``OUTPUT_COOLHEAT``) |
| SurfaceArea | AREA | $`\text{UnitLength}^2`$ $`a^2 \, h^{-2}`$ | Surface area of a Voronoi cell (``OUTPUT_SURFACE_AREA``) |
| NumFacesCell | NFAC | | Number of faces of a Voronoi cell (``OUTPUT_SURFACE_AREA``) |
| CoolingRate | COOR | erg cm$`^3`$ s$`^{-1}`$ | The cooling rate of a gas cell (e.g. Lambda_net/$`n_H^2`$). (``OUTPUTCOOLRATE``) |
| Vorticity | VORT | $`\text{UnitVelocity}`$ $`\text{UnitLength}^{-1}`$ $`h`$ | Vorticity of a cell (``OUTPUT_VORTICITY``) |
| PressureGradient | GRAP | $`\text{UnitLength}^{-4}`$ $`\text{UnitMass}`$ $`\text{UnitVelocity}^2`$ $`a^{-4} \, h^3`$ | Gradient of the pressure (limited) (``OUTPUT_PRESSURE_GRADIENT``) |
| DensityGradient | GRAR | $`\text{UnitLength}^{-4}`$ $`\text{UnitMass}`$ $`a^{-4} \, h^3`$ | Gradient of the density (limited) (``OUTPUT_DENSITY_GRADIENT``) |
| VelocityGradient | GRAV | $`\text{UnitLength}^{-1}`$ $`\text{UnitVelocity}`$ $`h`$ | Gradient of the velocity (limited) (``OUTPUT_VELOCITY_GRADIENT``) |
| BfieldGradient | GRAB | $`\text{UnitMass}^{0.5}`$ $`\text{UnitVelocity}`$ $`\text{UnitLength}^{-5/2}`$ $`h^2 \, a^{-3}`$ | Gradient of the magnetic field (limited) (``OUTPUT_BFIELD_GRADIENT``) |
| Volume | VOL | $`\text{UnitLength}^3`$ $`a^3 \, h^{-3}`$ | (comoving) volume of gas cell. Can be calculated by Masses / Density. (``OUTPUT_VOLUME``) |
| VertexVelocity | VEVE | $`\text{UnitVelocity}`$ $`a^1`$ | velocity of the mesh-generating point (``OUTPUT_VERTEX_VELOCITY``) |
| MaxFaceAngle | FACA | | Maximum face angle of cell, quantifies roundness (``OUTPUT_MESH_FACE_ANGLE``) |
| CenterOfMass | CMCE | $`\text{UnitLength}`$ $`a^1 \, h^{-1}`$ | Center of mass of cell. Generally not equal to position of mesh generating point ``POS`` (``OUTPUT_CENTER_OF_MASS``) |
| task | TASK | | MPI task this particle is at (``OUTPUT_TASK``) |
| TimebinHydro | TBH | | Time bin the cell is at (``OUTPUT_TIMEBIN_HYDRO``) |
| TimeStep | TSTP | $`\text{UnitLength}`$ $`\text{UnitVelocity}^{-1}`$ $`h^{-1}`$ | Timestep in code units (``OUTPUTTIMESTEP``) |
| Acceleration | ACCE | $`\text{UnitVelocity}^2`$ $`\text{UnitLength}^{-1}`$ $`a^{-1} \, h`$ | Acceleration due to gravitational forces, including external potential; different a scaling than internally!(``OUTPUTACCELERATION``)|
| Softenings | SOFT | $`\text{UnitLength}`$ $`a \, h^{-1}`$ | Gravitational softening length of particle/cell (``OUTPUT_SOFTENINGS``) |
| GravityInteractions | GINT | | Number of foce calculations in tree (``OUTPUTGRAVINTERACTIONS``) |
| MagneticField | BFLD | $`\text{UnitLength}^{-1.5}`$ $`\text{UnitMass}^{0.5}`$ $`\text{UnitVelocity}`$ $`h \, a^{-2}`$ | Magnetic field (in code units but Gauss system; note that internally, the Heaviside-Lorentz system is used) (``MHD``) |
| MagneticFieldDivergence | DIVB | $`\text{UnitLength}^{-2.5}`$ $`\text{UnitMass}^{0.5}`$ $`\text{UnitVelocity}`$ $`h^2 \, a^{-3}`$ | Divergence of magnetic field (``MHD``) |
| PassiveScalars | PASS | | Mass fraction of passive scalar quantity in cell (``PASSIVE_SCALARS``) |
| SubfindDensity | SFDE | $`\text{UnitLength}^{-3}`$ $`\text{UnitMass}`$ $`a^{-3} \, h^2`$ | density around particle (SPH like estimate) (``SAVE_HSML_IN_SNAPSHOT``) |
| SubfindDMDensity | SFDD | $`\text{UnitLength}^{-3}`$ $`\text{UnitMass}`$ $`a^{-3} \, h^2`$ | dark matter density around particle (SPH like estimate) (``SAVE_HSML_IN_SNAPSHOT``) |
| SubfindHsml | SFHS | $`\text{UnitLength}`$ $`a \, h^{-1}`$ | SPH smoothing length for density estimate (``SAVE_HSML_IN_SNAPSHOT``) |
| SubfindVelDisp | SFVD | $`\text{UnitVelocity}`$ | SPH avaraged velocity dispersion around particle (``SAVE_HSML_IN_SNAPSHOT``) |
| GroupNr | GROU | | Number of nearest group (``FOF_FUZZ_SORT_BY_NEAREST_GROUP=1``) |
| HighResGasMass | HRGM | $`\text{UnitMass}`$ $`h^{-1}`$ | Conserved scalar quantity flaging the high-res region of a cosmological zoom simulation (``REFINEMENT_HIGH_RES_GAS``) |
| AllowRefinement | REF | | Is refinement allowed in gas cell. 0 for low-resolution region gas cells in zoom simulations (``REFINEMENT_HIGH_RES_GAS``) |
Format 1
--------
......@@ -441,5 +398,4 @@ algorithm), and ``Subhalo``, for substructures in groups.
| Subhalo_CMFracInRad | SCMR | | Mass fraction of counter-rotating particles in a sphere with twice the stellar half mass radius |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
| Subhalo_CMFracTypeInRad | SCTR | | Mass fraction of counter-rotating particles in a sphere with twice the stellar half mass radius for each type |
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
+-----------------------------+--------------+----------------------------------------------------------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------------+
\ No newline at end of file
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