LOS - lightcone-like
We provide 300 lines of sights (LOS) of this type. We employ a stepwise-constant approximation to built them. In practice, we combine the properties of the simulation
extracted from the same LOS (specifically, the z-aligned LOS) at different snapshots. The length of each chunk employed is
the light travel distance between the time of the snapshot and of the next one. For the last snapshot (80, corresponding to \( z=5.5 \) ) we employ the full
length of the LOS (equal to the simulation box size, i.e. \( 95.5 cMpc \) ). We employ periodic boundary condition.
They originate from random position on the \( z=0 \) plane and are directed towards the positive z direction (i.e. their direction is \( [0,0,1] \).
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).
| Root attributes ▾ |
|---|
| 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. |
| Datasets and groups ▾ |
|---|
| 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. |
| Pixel_Position | group | BoxSize | 3D coordinates in the simulation box (in units of BoxSize) of the segment, including periodic boundary conditions. |
| RayDirections | (Nlos,3) | - | Direction of each LOS. |
| RayOrigins | (Nlos,3) | \( ckpc/h \) | Starting point of the LOS. |
| RaySegments | group | \( ckpc/h \) | Length of each segment composing the LOS. These segments are the intersection of the LOS with the Voronoi tesselation. |
| Redshift | group | Redshift of each segment. Notice that this is the redshift the segment would have if the LOS was extracted from a real lightcone (i.e. without piecewise-constant approximation). To know the actual redshift, see the field 'Snapshot'. | |
| Snapshot | group | Snapshot from which each segment was extracted. | |
| 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. |
