Global constants

Characteristic stellar age limit for the SFR and sSFR.

Reference exponent for the molecular fraction-pressure relation, taken from Blitz et al. (2006) (Table 2, "Mean" row, Second column).

We use -α here.

References

L. Blitz et al. (2006). The Role of Pressure in GMC Formation II: The H2-Pressure Relation. The Astrophysical Journal, 650(2), 933. doi:10.1086/505417

Standard atomic weights.

References

T. Prohaska et al. (2022). Standard atomic weights of the elements 2021 (IUPAC Technical Report). Pure and Applied Chemistry, 94(5), 573-600. doi:10.1515/pac-2019-0603

Kennicutt-Schmidt law best-fit for molecular gas, from Bigiel et al. (2008) (Section 4.3, Equation 3).

Power-law index, N, and $A = \log_{10}(a)$, where $a$ is $\Sigma_\mathrm{SFR}$ at the fiducial gas surface density of $10 \, \mathrm{M_\odot \, pc^{-2}}$ are given.

\[\Sigma_\mathrm{SFR} = a \left( \frac{\Sigma_\mathrm{H_2}}{10 \, \mathrm{M_\odot \, pc^{-2}}} \right)^{\!N} \, ,\]

References

F. Bigiel et al. (2008). THE STAR FORMATION LAW IN NEARBY GALAXIES ON SUB-KPC SCALES. The Astrophysical Journal, 136(6), 2846. doi:10.1088/0004-6256/136/6/2846

Kennicutt-Schmidt law fits for molecular and neutral gas, from Bigiel et al. (2008) (Table 2, Average).

Power-law index, N, and $A = \log_{10}(a)$, where $a$ is $\Sigma_\mathrm{SFR}$ at the fiducial gas surface density of $10 \, \mathrm{M_\odot \, pc^{-2}}$ are given.

\[\Sigma_\mathrm{SFR} = a \left( \frac{\Sigma_\mathrm{HI, H_2, gas}}{10 \, \mathrm{M_\odot \, pc^{-2}}} \right)^{\!N} \, ,\]

References

F. Bigiel et al. (2008). THE STAR FORMATION LAW IN NEARBY GALAXIES ON SUB-KPC SCALES. The Astrophysical Journal, 136(6), 2846. doi:10.1088/0004-6256/136/6/2846

Range of values for

\[\Sigma_\mathrm{SFR} \, [\mathrm{M_\odot \, yr^{-1} \, kpc^{-2}}] \, ,\]

in the seven spiral in Table 1 of Bigiel et al. (2008), with associated molecular data.

The actual values for the SFR density are taken from Table 2 in Bigiel et al. (2010), using only the ones with associated molecular data.

References

F. Bigiel et al. (2008). THE STAR FORMATION LAW IN NEARBY GALAXIES ON SUB-KPC SCALES. The Astrophysical Journal, 136(6), 2846. doi:10.1088/0004-6256/136/6/2846

F. Bigiel et al. (2010). EXTREMELY INEFFICIENT STAR FORMATION IN THE OUTER DISKS OF NEARBY GALAXIES. The Astrophysical Journal, 140(5), 1194. doi:10.1088/0004-6256/140/5/1194

Path to the file with Table 2 from Bigiel et al. (2010).

References

F. Bigiel et al. (2010). EXTREMELY INEFFICIENT STAR FORMATION IN THE OUTER DISKS OF NEARBY GALAXIES. The Astrophysical Journal, 140(5), 1194. doi:10.1088/0004-6256/140/5/1194

Path to the file with Table 3 from Bigiel et al. (2010).

References

F. Bigiel et al. (2010). EXTREMELY INEFFICIENT STAR FORMATION IN THE OUTER DISKS OF NEARBY GALAXIES. The Astrophysical Journal, 140(5), 1194. doi:10.1088/0004-6256/140/5/1194

Spatial resolution used in Bigiel et al. (2008).

References

F. Bigiel et al. (2008). THE STAR FORMATION LAW IN NEARBY GALAXIES ON SUB-KPC SCALES. The Astrophysical Journal, 136(6), 2846. doi:10.1088/0004-6256/136/6/2846

Characteristic box size.

Cosmological threshold density above which the gas cells/particles can turn into stars.

This value corresponds to CritOverDensity $= 57.7 \, [\mathrm{cm^{-3}}]$ in the param.txt file (used only in cosmological simulations). Which is converted to internal units within the code using OverDensThresh = CritOverDensity * OmegaBaryon * 3 * Hubble * Hubble / (8 * M_PI * G). Then, to go to physical units again one has to do:OverDensThresh*UnitDensityincgs*cf_a3inv*HubbleParam*HubbleParam`.

Using the unit factors,

UnitLength_in_cm = $3.085678 \times 10^{24}$

UnitMass_in_g = $1.989 \times 10^{43}$

UnitVelocity_in_cm_per_s = $100000$

The derived units,

UnitTime_in_s = UnitLength_in_cm * UnitVelocity_in_cm_per_s^-1 = $3.08568 \times 10^{19}$

UnitDensity_in_cgs = UnitMass_in_g * UnitLength_in_cm^-3 = $6.76991 \times 10^{-31}$

The parameters,

OmegaBaryon = $0.048$

HubbleParam = $0.6777$

PROTONMASS = $1.67262178 \times 10^{-24}$

HYDROGEN_MASSFRAC = $0.76$

GRAVITY = $6.6738 \times 10^{-8}$

HUBBLE = $3.2407789 \times 10^{-18}$

And the derived parameters,

Hubble = HUBBLE * UnitTime_in_s = $100$

G = GRAVITY * UnitLength_in_cm^-3 * UnitMass_in_g * UnitTime_in_s^2 = $43.0187$

One gets,

OverDensThresh = 76.8495 [internal units of density]

And, for a cosmological simulation at redshift 0 (cf_a3inv = 1), this result in a physical density threshold of $1.42857 \times 10^{-5} \, [\mathrm{cm^{-3}}]$, or adding the proton mass a value of:

$\log_{10} \rho \ [\mathrm{M_\odot \, kpc^{-3}}] = 2.548$

Relative path, within the simulation directory, of the cpu.txt file.

Default cycler.

Color type.

Default plot theme.

Regarding the graphic units used, we know that $1 \, \mathrm{mm} = 2.83466 \, \mathrm{pt}$ and $1 \, \mathrm{in} = 25.4 \, \mathrm{mm}$. Then, if we want $1 \, \mathrm{[code\,\,]unit} = 0.1 \, \mathrm{mm}$ in vector graphics, we have to use pt_per_unit = 0.283466.

For pixel images, we control the ppi with px_per_unit. A reasonable high ppi is 600. So, using px_per_unit = $2.3622$ we get $23.622 \, \mathrm{px/mm} \sim 600 \, \mathrm{px/in}$ (remember that $1 \, \mathrm{[code\,\,]unit} = 0.1 \, \mathrm{mm}$).

Characteristic radius.

Path to the file with the global galactic properties from Feldmann (2020).

References

R. Feldmann (2020). The link between star formation and gas in nearby galaxies. Communications Physics 3(226). doi:10.1038/s42005-020-00493-0

Symbol list for the gas abundance quantities.

Subhalo numbers for the MW and M31 in Hestia simulations.

Hubble constant in $\mathrm{Gyr^{-1}}$.

This value corresponds to $H_0 = 0.102201 \, \mathrm{Gyr}^{-1} = 100 \, \mathrm{km} \, \mathrm{s}^{-1} \, \mathrm{Mpc}^{-1}$.

Internal unit of length used in IllustrisTNG, equivalent to $1.0 \, \mathrm{kpc}$. See the documentation here

Internal unit of mass used in IllustrisTNG, equivalent to $10^{10} \, \mathrm{M_\odot}$. See the documentation here

Internal unit of velocity used in IllustrisTNG, equivalent to $1.0 \, \mathrm{km \, s^{-1}}$. See the documentation here

Type of cell/particle corresponding to each code index.

Human readable name for each type of cell/particle.

Index type.

Range of values for

\[\Sigma_\mathrm{SFR} \, [\mathrm{M_\odot \, yr^{-1} \, kpc^{-2}}] \, ,\]

from the combine data (Table 1 and 2) in Kennicutt (1998).

References

R. C. Kennicutt (1998). The Global Schmidt Law in Star-forming Galaxies. The Astrophysical Journal, 498(2), 541-552. doi:10.1086/305588

Path to the file with the data from Leroy et al. (2008).

References

A. K. Leroy et al. (2008). THE STAR FORMATION EFFICIENCY IN NEARBY GALAXIES: MEASURING WHERE GAS FORMS STARS EFFECTIVELY. The Astronomical Journal 136(6), 2782–2845. doi:10.1088/0004-6256/136/6/2782

Default list of line styles.

Code index for each type of cell/particle.

References

See for example Gadget2 User's Guide, or Gadget4 documentation.

Human readable name for each type of cell/particle.

Line style type.

Default list of marker types.

Path to the file with the fits from McMillan (2011).

References

P. J. McMillan (2011). Mass models of the Milky Way. Monthly Notices of the Royal Astronomical Society 414(3), 2446–2457. doi:10.1111/j.1365-2966.2011.18564.x

Path to the file with the Milky Way profiles from Mollá et al. (2015).

References

M. Mollá et al. (2015). Galactic chemical evolution: stellar yields and the initial mass function. Monthly Notices of the Royal Astronomical Society 451(4), 3693–3708. doi:10.1093/mnras/stv1102

Human readable name for each morphological component.

Slope of the Kennicutt-Schmidt law, taken from Kennicutt (1998) (Section 4, Equation 4).

\[\Sigma_\mathrm{SFR} = a \left( \frac{\Sigma_\mathrm{gas}}{1 \, \mathrm{M_\odot \, pc^{-2}}} \right)^{\!N} \mathrm{M_\odot \, yr^{-1} \, kpc^{-2}} \, ,\]

References

R. C. Kennicutt (1998). The Global Schmidt Law in Star-forming Galaxies. The Astrophysical Journal, 498(2), 541-552. doi:10.1086/305588

Reference pressure for the molecular fraction-pressure relation, taken from Blitz et al. (2006) (Table 2, "Mean" row, Third column).

References

L. Blitz et al. (2006). The Role of Pressure in GMC Formation II: The H2-Pressure Relation. The Astrophysical Journal, 650(2), 933. doi:10.1086/505417

Internal code name (data group in the HDF5 output) corresponding to each type of cell/particle.

Type of cell/particle corresponding to each internal code name (data group in the HDF5 output).

Default filter dictionary that does not exclude any cells/particles.

Filter that excludes every cell/particle.

If physical units (lengths) will be used, instead of comoving units (lengths).

Reduced index type.

Relative path, within the simulation directory, of the sfr.txt file.

Solar abundances.

They are defined as $12 + \log_{10}(N_\mathrm{X} / N_\mathrm{H})$, where $N_\mathrm{X}$ and $N_\mathrm{H}$ are the number densities of element $\mathrm{X}$ and hydrogen respectively.

References

M. Asplund et al. (2009). The Chemical Composition of the Sun. Annual Review of Astronomy and Astrophysics, 47(1), 481–522. doi:10.1146/annurev.astro.46.060407.145222

Symbol list for the stellar abundance quantities.

Path to the file with Table A1 from Sun et al. (2023).

References

J. Sun et al. (2023). Star Formation Laws and Efficiencies across 80 Nearby Galaxies. The Astrophysical Journal Letters, 945(2), L19. doi:10.3847/2041-8213/acbd9c

Spatial resolution used in Sun et al. (2023).

References

J. Sun et al. (2023). Star Formation Laws and Efficiencies across 80 Nearby Galaxies. The Astrophysical Journal Letters, 945(2), L19. doi:10.3847/2041-8213/acbd9c

Threshold density above which the gas cells/particles can turn into stars.

This value corresponds to CritPhysDensity $= 0.318 \, [\mathrm{cm^{-3}}]$ in the param.txt file (used in cosmological and non-cosmological simulations). Which is converted to internal units within the code using PhysDensThresh = CritPhysDensity * PROTONMASS / HYDROGEN_MASSFRAC / UnitDensity_in_cgs. Then, to go to physical units again one has to do: PhysDensThresh * UnitDensity_in_cgs * cf_a3inv * HubbleParam * HubbleParam.

PhysDensThresh = $1.03378 \times 10^{6}$ [internal units of density]

For a cosmological simulation at redshift 0 (cf_a3inv = 1), this result in a physical density threshold of $0.192 \, [\mathrm{cm^{-3}}]$, or adding the proton mass a value of:

$\log_{10} \rho \, [\mathrm{M_\odot \, kpc^{-3}}] = 6.677$

Intercept of the Kennicutt-Schmidt law, taken from Kennicutt (1998) (Section 4, Equation 4).

\[\Sigma_\mathrm{SFR} = a \left( \frac{\Sigma_\mathrm{gas}}{1 \, \mathrm{M_\odot \, pc^{-2}}} \right)^{\!N} \mathrm{M_\odot \, yr^{-1} \, kpc^{-2}} \, ,\]

References

R. C. Kennicutt (1998). The Global Schmidt Law in Star-forming Galaxies. The Astrophysical Journal, 498(2), 541-552. doi:10.1086/305588

If logging messages will be printed out.

Circular grid (2D or 3D).

Series of concentric rings or spherical shells.

Fields

• grid::Vector{<:Number}: Vector with the distance of each bin to the center of the grid.
• ticks::Vector{<:Number}: Vector with the edges of the bins.
• center::Vector{<:Number}: 3D location of the center of the grid. In the 2D case the grid is assumed to be in the xy plane.
• bin_area::Vector{<:Number}: Area of each ring.
• bin_volumes::Vector{<:Number}: Volume of each spherical shell.
• log::Bool: If the grid is logarithmic.

Cubic grid (3D).

Fields

• grid::Array{NTuple{3,<:Number},3}: Matrix with the physical coordinates of each voxel in the grid.
• x_ticks::Vector{<:Number}: Full set of possible values for the x coordinate.
• y_ticks::Vector{<:Number}: Full set of possible values for the y coordinate.
• z_ticks::Vector{<:Number}: Full set of possible values for the z coordinate.
• physical_size::Number: Side length of the cubic grid.
• n_bins::Int: Number of bins per side of the grid.
• bin_width::Number: Side length of each bin.
• bin_area::Number: Face area of each bin.
• bin_volume::Number: Volume of each bin.

Data in the "Header" group of a HDF5 group catalog file.

Default values are for when there are no group catalog files.

Fields

• box_size::Float64 = NaN: Total size of the simulation box.
• h::Float64 = NaN: Hubble parameter.
• n_groups_part::Int32 = -1: Number of halos (FoF groups) in this file chunk.
• n_groups_total::Int32 = -1: Total number of halos (FoF groups) in this snapshot.
• n_subgroups_part::Int32 = -1: Number of subhalos (subfind) in this file chunk.
• n_subgroups_total::Int32 = -1: Total number of subhalos (subfind) in this snapshot.
• num_files::Int32 = -1: Number of file chunks per snapshot.
• omega_0::Float64 = NaN: The cosmological density parameter for matter.
• omega_l::Float64 = NaN: The cosmological density parameter for the cosmological constant.
• redshift::Float64 = NaN: The redshift.
• time::Float64 = NaN: The physical time/scale factor.

Metadata for a group catalog file.

Fields

• path::Union{String,Missing}: Full path to the group catalog file.
• header::GroupCatHeader: Header of the group catalog.

Unit conversion factors.

Fields

• x_cgs::Unitful.Length: Length, from internal units to $\mathrm{cm}$.
• x_cosmo::Unitful.Length: Length, from internal units to $\mathrm{kpc}$.
• x_comoving::Unitful.Length: Length, from internal units to $\mathrm{ckpc}$.
• v_cgs::Unitful.Velocity: Velocity, from internal units to $\mathrm{cm \, s^{-1}}$.
• v_cosmo::Unitful.Velocity: Velocity, from internal units to $\mathrm{km \, s^{-1}}$.
• m_cgs::Unitful.Mass: Mass, from internal units to $\mathrm{g}$.
• m_cosmo::Unitful.Mass: Mass, from internal units to $\mathrm{M_\odot}$.
• t_cgs::Unitful.Time: Time, from internal units to $\mathrm{s}$.
• t_cosmo::Unitful.Time: Time, from internal units to $\mathrm{Myr}$.
• U_cgs::Unitful.Energy: Specific energy, from internal units to $\mathrm{erg \, g^{-1}}$.
• rho_cgs::Unitful.Density: Density, from internal units to $\mathrm{g \, cm^{-3}}$.
• P_Pa::Unitful.Pressure: Pressure, from internal units to $\mathrm{Pa}$.

Linear grid (1D).

Fields

• grid::Vector{<:Number}: Vector with the central value of each bin.
• ticks::Vector{<:Number}: Vector with the edges of the bins.
• bin_widths::Vector{<:Number}: Widths of the bins.
• log::Bool: If the grid is logarithmic.

Plotting parameters for a quantity.

Fields

• request::Dict{Symbol,Vector{String}} = Dict{Symbol,Vector{String}}(): Data request for readSnapshot. It must have the shape cell/particle type -> [block, block, block, ...].
• var_name::AbstractString = "": Name of the quantity for the plot axis. It should not include units or scaling factors.
• exp_factor::Int = 0: Numerical exponent to scale down the axis, e.g. if x_exp_factor = 10 the values will be divided by $10^{10}$. The default is no scaling.
• unit::Unitful.Units = Unitful.NoUnits: Target unit for the axis.
• axis_label::AbstractString = "auto_label": Label for the axis. It can contain the string auto_label, which will be replaced by the default label: var_name / 10^exp_factor unit.

Dimensional information about a physical quantity.

Fields

• hdf5_name::String: HDF5 block name.
• dimensions::Unitful.Dimensions: Physical dimensions of the quantity, e.g. Unitful.𝐋 * Unitful.𝐓^-1.
• unit::Union{Unitful.Units,Symbol}: Units of the quantity within the simulation code. It can be a unit from Unitful or UnitfulAstro, or it can be the symbol :internal which denotes internal code units.

Metadata for a simulation.

Fields

• path::String: Full path to the simulation directory.

• index::Int: An index associated with the simulation.

• slice::IndexType: Slice of the simulation, i.e. which snapshots will be read. It can be an integer (a single snapshot), a vector of integers (several snapshots), an UnitRange (e.g. 5:13), an StepRange (e.g. 5:2:13) or (:) (all snapshots).

• cosmological::Bool: If the simulation is cosmological,

  • false -> Newtonian simulation (ComovingIntegrationOn = 0).
  • true -> Cosmological simulation (ComovingIntegrationOn = 1).

• table::DataFrame: A dataframe where each row is a snapshot, and the following 8 colums:

  • :ids -> Dataframe index of each snapshot, i.e. if there are 10 snapshots in total it runs from 1 to 10.
  • :numbers -> Number in the file name of each snapshot.
  • :scale_factors -> Scale factor of each snapshot.
  • :redshifts -> Redshift of each snapshot.
  • :physical_times -> Physical time since the Big Bang.
  • :lookback_times -> Physical time left to reach the last snapshot.
  • :snapshot_paths -> Full path to each snapshots.
  • :groupcat_paths -> Full path to each group catalog files.

Metadata for a snapshot.

Fields

• path::String: Full path to the snapshot.
• global_index::Int: Index of the snapshot in the context of the whole simulation.
• slice_index::Int: Index of the snapshot in the context of the slice.
• physical_time::Unitful.Time: Physical time since the Big Bang.
• lookback_time::Unitful.Time: Physical time left to reach the last snapshot.
• scale_factor::Float64: Scale factor of the snapshot.
• redshift::Float64: Redshift of the snapshot.
• header::SnapshotHeader: Header of the snapshot.

Data in the "Header" group of a HDF5 snapshot file.

Fields

• box_size::Float64: Total size of the simulation box.
• h::Float64: Hubble parameter.
• mass_table::Vector{Float64}: Masses of particle types which have a constant mass.
• num_files::Int32: Number of file chunks per snapshot.
• num_part::Vector{Int32}: Number of particles (of each type) included in this file chunk.
• num_total::Vector{UInt32}: Total number of particles (of each type) for this snapshot.
• omega_0::Float64: The cosmological density parameter for matter.
• omega_l::Float64: The cosmological density parameter for the cosmological constant.
• redshift::Float64: The redshift.
• time::Float64: The physical time/scale factor.
• l_unit::Unitful.Length: Conversion factor from internal units of length to centimeters.
• m_unit::Unitful.Mass: Conversion factor from internal units of mass to grams.
• v_unit::Unitful.Velocity: Conversion factor from internal units of velocity to centimeters per second.

Square grid (2D).

Fields

• grid::Matrix{NTuple{2,<:Number}}: Matrix with the physical coordinates of each pixel in the grid.
• x_ticks::Vector{<:Number}: Full set of possible values for the x coordinate.
• y_ticks::Vector{<:Number}: Full set of possible values for the y coordinate.
• physical_size::Number: Side length of the square grid.
• n_bins::Int: Number of bins per side of the grid.
• bin_width::Number: Side length of each bin.
• bin_area::Number: Area of each bin.