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LOS - aligned with z direction
We provide 300 lines of sights (LOS) of this type for each snapshot from the 54th onward. They are initialized from random position on the \( z=0 \) plane and
with direction towards the positive z direction (i.e. \( [0,0,1] \). They have length equal to the box size \( 95.5 cMpc \).
These are available only for Thesan-1 at the moment.
The LOS for each snapshot are stored in a different HDF5 file.
This file contains general information in the attributes of the Header group (in a similar way to most other data product). The available attributes are listed in the table below (click to open).
| Attribute |
Dimensions |
Units |
Description |
| BoxSize |
1 |
\( ckpc / h \) |
Spatial extent of the periodic box (in comoving units). |
| HubbleParam |
1 |
- |
Little \( h \), defined as \( h = H_0 / (100 km/s/Mpc) \) |
| MultipleOrigins |
1 |
- |
Flag indicating that the LOS have different origins within the simulation box. |
| NumRays |
1 |
- |
Number of LOS stored in the file. |
| Omega0 |
1 |
- |
The cosmological density parameter for matter. |
| OmegaBaryon |
1 |
- |
The cosmological density parameter for baryons. |
| RayImpact |
1 |
- |
Meaningless for the current configuration. |
| RayLength |
1 |
\( ckpc/h \) |
Length of the LOS. |
| RayLength_cMpc |
1 |
\( ckpc \) |
Length of the LOS in \( cMpc \). |
| RaySphere |
1 |
- |
Meaningless for the current configuration. |
| Redshift |
1 |
- |
The redshift corresponding to the current snapshot. |
| UnitLength_in_cm |
1 |
- |
Length unit used in the simulation, expressed in comoving cm. |
| UnitMass_in_g |
1 |
- |
Mass unit used in the simulation, expressed in g. |
| UnitVelocity_in_cm_per_s |
1 |
- |
Velocity unit used in the simulation, expressed in comoving cm / s. |
Within each LOS file, the properties extracted along the LOS are saved in a number of groups, each one containing a dataset for each ray (named simply with a progressive number, starting from 0).
These values are directly extracted from the simulation cell crossed by the ray, and saved as they are. This means that the units and considerations made for such fields (see Snapshots) apply directly to the ray fields.
Additionally, LOS properties are saved in a mix of groups (with the same format just described) and datasets. Both are described in the table below (click to open).
We distinguish groups from dataset in the dimensions column.
| Dataset |
Dim. |
Units |
Description |
|
|
|
|
| Density |
group |
\( 10^{10} M_\odot h^2 / ckpc^3 \) |
Gas density in the Voronoi cell. Internal units. |
| ElectronAbundance |
group |
- |
Electron abundance, defined as \( n_e / n_H \), in each Voronoi cell. |
| GFM_DustMetallicity |
group |
- |
Dust-to-metal ratio in each Voronoi cell. |
| GFM_Metallicity |
group |
- |
Gas-phase metallicity in each Voronoi cell. |
| GFM_Metals |
group |
- |
For each ray, contains the mass fracion of nine species: H, He, C, N, O, Ne, Mg, Si, Fe (in this order). Each one is the dimensionless ratio of mass in that species to the total gas cell mass. |
| HI_Fraction |
group |
- |
HI fraction (i.e. \(n_{HI} / n_H \) ) in the cell. |
| HeI_Fraction |
group |
- |
HeI fraction (i.e. \(n_{HeI} / n_H \) ) in the cell. Note: the denominator is \(n_H\), rather than \(n_{He}\). |
| HeII_Fraction |
group |
- |
HeII fraction (i.e. \(n_{HeII} / n_H \) ) in the cell. Note: the denominator is \(n_H\), rather than \(n_{He}\). |
| InternalEnergy |
group |
\( (km/s)^2 \) |
Internal energy of the gas in the Voronoi cell. |
| MagneticField |
group |
\( (h/a^2) \sqrt{}\)UnitPressure |
Three-dimensional magnetic field. |
| PhotonDensity |
group |
#\( (ckpc/h^3) / 10^{63} \) |
Density of photons in the cells in the three spectral bands tracked in Thesan. |
| RayOrigins |
(Nlos,3) |
\( ckpc/h \) |
Starting point of the LOS. |
| RayEndings |
(Nlos,3) |
\( ckpc/h \) |
End point of the LOS. Note that this does not include the box wrapping due to PBC, so this value can nominally lie outside of the simulation box, although the rays include PBC.. |
| RaySegments |
group |
\( ckpc/h \) |
Length of each segment composing the LOS. These segments are the intersection of the LOS with the Voronoi tesselation. |
| StarFormationRate |
group |
\( M_\odot / yr \) |
Star Fromation Rate of the gas. |
| Velocity |
group |
\( km \sqrt{a} /s \) |
Spatial velocity. Multiply this value by \(\sqrt{a}\) to obtain peculiar velocity. |
