.. _fields:

.. raw:: html

   <style> .dv {color:#839192; font-weight:bold; font-style: italic} </style>

.. role:: dv

Field Names and Descriptions
============================

COLT aims to have short but intuitive names for its internal fields. This page provides a list of internal fields along with brief descriptions, units, and notes that might be helpful to remember for users or developers. Many fields are optional and only allocated when necessary and most can be used wih the projections module.

.. _Gas Fields:

Gas Fields
----------

* ``n_cells`` -- Number of cells :math:`n_\text{cells}`. In general, gas fields are arrays with this many elements.

* ``r`` -- Position coordinates :math:`(x,y,z)`. Each geometry may interpret this differently. :dv:`[Units: cm]`

* ``V`` -- Cell volume :math:`V`. :dv:`[Units: cm^3]`

* ``v`` -- Bulk velocity :math:`(v_x,v_y,v_z)`. :dv:`[Units: cm/s]`

* ``dvdr`` -- Bulk velocity gradient :math:`\text{d}v/\text{d}r`. :dv:`[Units: 1/s]`

* ``v0`` -- Velocity extrapolation :math:`v_0 = v - r \nabla v`. :dv:`[Units: cm/s]`

* ``rho`` -- Gas density :math:`\rho`. :dv:`[Units: g/cm^3]`

* ``T`` -- Temperature :math:`T`. :dv:`[Units: K]`

* ``e_int`` -- Internal energy :math:`e_\text{int}`. :dv:`[Units: cm^2/s^2]`

* ``n_H`` -- Hydrogen number density :math:`n_\text{H}`. :dv:`[Units: cm^-3]`

* ``n_He`` -- Helium number density :math:`n_\text{He}`. :dv:`[Units: cm^-3]`

* ``n_C`` -- Carbon number density :math:`n_\text{C}`. :dv:`[Units: cm^-3]`

* ``n_N`` -- Nitrogen number density :math:`n_\text{N}`. :dv:`[Units: cm^-3]`

* ``n_O`` -- Oxygen number density :math:`n_\text{O}`. :dv:`[Units: cm^-3]`

* ``n_Ne`` -- Neon number density :math:`n_\text{Ne}`. :dv:`[Units: cm^-3]`

* ``n_Mg`` -- Magnesium number density :math:`n_\text{Mg}`. :dv:`[Units: cm^-3]`

* ``n_Si`` -- Silicon number density :math:`n_\text{Si}`. :dv:`[Units: cm^-3]`

* ``n_S`` -- Sulfer number density :math:`n_\text{S}`. :dv:`[Units: cm^-3]`

* ``n_Fe`` -- Iron number density :math:`n_\text{Fe}`. :dv:`[Units: cm^-3]`

* ``n_upper`` and ``n_lower`` -- Number density of the upper and lower transitions of a two-level atom :math:`n_\text{upper}` and :math:`n_\text{lower}`. :dv:`[Units: cm^-3]`

* ``x_HI`` and ``x_HII`` -- Hydrogen ionization fractions for neutral and ionized gas (:math:`x_\text{HI} = n_\text{HI} / n_\text{H}`). There are also ionized fractions for metal number densities under the convention that each is normalized to unity for the given species, e.g. for helium (:math:`x_\text{HeI} = n_\text{HeI} / n_\text{He}`) :dv:`[Units: mass fraction]`

* ``x_H2`` -- Molecular hydrogen mass fraction (:math:`x_\text{H_2} = n_\text{H_2} / n_\text{H}`). :dv:`[Units: cm^-3]`

* ``x_e`` -- Electron abundance relative to hydrogen (:math:`x_e = n_e / n_\text{H}`). :dv:`[Units: cm^-3]`

* ``G_ion`` -- Total photoheating rate :math:`\Gamma_\text{ion}`. :dv:`[Units: erg/s]`

* ``SFR`` -- Star formation rate. :dv:`[Units: Msun/yr]`

* ``T_dust`` -- Dust temperature :math:`T_\text{dust}`. :dv:`[Units: K]`

* ``v2`` -- Velocity squared :math:`v^2`. :dv:`[Units: cm^2/^2]`

* ``v2_LOS`` -- Line-of-sght velocity squared :math:`v_\text{LOS}^2`. :dv:`[Units: cm^2/s^2]`

* ``v_LOS`` -- Line-of-sght velocity :math:`v_\text{LOS}`. :dv:`[Units: cm/s]`

* ``v_x`` -- Velocity in the camera x-axis direction :math:`v_x`. :dv:`[Units: cm/s]`

* ``v_y`` -- Velocity in the camera y-axis direction :math:`v_y`. :dv:`[Units: cm/s]`

* ``B`` -- Magnetic field :math:`B`. :dv:`[Units: Gauss]`

* ``B2`` -- Magnetic field squared :math:`B^2`. :dv:`[Units: Gauss^2]`

* ``B_LOS`` -- Line-of-sight magnetic field :math:`B_\text{LOS}`. :dv:`[Units: Gauss]`

* ``B_x`` -- Magnetic field in the camera x-axis direction :math:`B_x`. :dv:`[Units: cm/s]`

* ``B_y`` -- Magnetic field in the camera y-axis direction :math:`B_y`. :dv:`[Units: cm/s]`

* ``X`` -- Mass fraction of hydrogen :math:`X = \rho_\text{H} / \rho`. :dv:`[Units: mass fraction]`

* ``Y`` -- Mass fraction of helium :math:`Y = \rho_\text{He} / \rho`. :dv:`[Units: mass fraction]`

* ``Z`` -- Gas metallicity :math:`Z = \rho_Z / \rho`. :dv:`[Units: mass fraction]`

* ``Z_C`` -- Carbon metallicity :math:`Z_\text{C} = \rho_\text{C} / \rho`. :dv:`[Units: mass fraction]`

* ``Z_N`` -- Nitrogen metallicity :math:`Z_\text{N} = \rho_\text{N} / \rho`. :dv:`[Units: mass fraction]`

* ``Z_O`` -- Oxygen metallicity :math:`Z_\text{O} = \rho_\text{O} / \rho`. :dv:`[Units: mass fraction]`

* ``Z_Ne`` -- Neon metallicity :math:`Z_\text{Ne} = \rho_\text{Ne} / \rho`. :dv:`[Units: mass fraction]`

* ``Z_Mg`` -- Magnesium metallicity :math:`Z_\text{Mg} = \rho_\text{Mg} / \rho`. :dv:`[Units: mass fraction]`

* ``Z_Si`` -- Silicon metallicity :math:`Z_\text{Si} = \rho_\text{Si} / \rho`. :dv:`[Units: mass fraction]`

* ``Z_S`` -- Sulfer metallicity :math:`Z_\text{S} = \rho_\text{S} / \rho`. :dv:`[Units: mass fraction]`

* ``Z_Fe`` -- Iron metallicity :math:`Z_\text{Fe} = \rho_\text{Fe} / \rho`. :dv:`[Units: mass fraction]`

* ``D`` -- Dust-to-gas ratio :math:`\mathcal{D} = \rho_\text{dust} / \rho`. :dv:`[Units: mass fraction]`

* ``D_S`` -- Silicate dust-to-gas ratio :math:`\mathcal{D}_\text{Si} = \rho_\text{dust,Si} / \rho`. :dv:`[Units: mass fraction]`

* ``D_PAH`` -- PAH dust-to-gas ratio :math:`\mathcal{D}_\text{PAH} = \rho_\text{dust,PAH} / \rho`. :dv:`[Units: mass fraction]`

* ``k_e`` -- Absorption coefficient of electrons :math:`k_e`. :dv:`[Units: 1/cm]`

* ``k_0`` -- Absorption coefficient of primary line :math:`k_0`. :dv:`[Units: 1/cm]`

* ``kp_0`` -- Absorption coefficient of doublet line :math:`k'_0`. :dv:`[Units: 1/cm]`

* ``k_dust`` -- Absorption coefficient of dust :math:`k_\text{dust}`. :dv:`[Units: 1/cm]`

* ``k_dust_scat_G`` -- Scattering coefficient of graphite dust :math:`k_\text{dust,G}^\text{scat}`. :dv:`[Units: 1/cm]`

* ``k_dust_scat_S`` -- Scattering coefficient of silicate dust :math:`k_\text{dust,S}^\text{scat}`. :dv:`[Units: 1/cm]`

* ``k_dust_scat_PAH`` -- Scattering coefficient of PAH dust :math:`k_\text{dust,PAH}^\text{scat}`. :dv:`[Units: 1/cm]`

* ``rho_dust`` -- Dust density :math:`\rho_\text{dust}`. :dv:`[Units: g/cm^3]`

* ``rho_dust_G`` -- Graphite dust density :math:`\rho_\text{dust,G}`. :dv:`[Units: g/cm^3]`

* ``rho_dust_S`` -- Silicate dust density :math:`\rho_\text{dust,S}`. :dv:`[Units: g/cm^3]`

* ``rho_dust_PAH`` -- PAH dust density :math:`\rho_\text{dust,PAH}`. :dv:`[Units: g/cm^3]`

* ``a`` -- Damping parameter for the Voigt function :math:`a`. :dv:`[Units: None]`

* ``atau`` -- Nonlocal estimate of :math:`a\tau_0` for each cell. :dv:`[Units: None]`

* ``j_line`` -- Primary line emissivity :math:`j`. :dv:`[Units: erg/s/cm^3]`

* ``jp_line`` -- Doublet line emissivity :math:`j'`. :dv:`[Units: erg/s/cm^3]`

* ``u_rad`` -- Path-based radiation energy density :math:`u_\text{rad}`. :dv:`[Units: erg/cm^3]`

* ``a_rad_path`` -- Path-based acceleration due to radiation pressure :math:`a_\text{rad}`. :dv:`[Units: cm/s^2]`

* ``a_rad_scat`` -- Scattering-based acceleration due to radiation pressure :math:`a_\text{rad,scat}`. :dv:`[Units: cm/s^2]`

* ``u_rad_r`` -- Path-based radiation energy density :math:`u_\text{rad}` (spherical and cylindrical coordinates). :dv:`[Units: erg/cm^3]`

* ``u_rad_r_e2`` -- Path-based sum of squared event-level contributions to the radiation energy density :math:`\sum_\text{events}(\Delta u_\text{rad})^2` (spherical coordinates). :dv:`[Units: erg^2/cm^6]`

* ``a_rad_r_path`` -- Path-based acceleration due to radiation pressure in the radial direction :math:`a_\text{rad}` (spherical and cylindrical coordinates). :dv:`[Units: cm/s^2]`

* ``a_rad_r_path_e2`` -- Path-based sum of squared event-level contributions to the radiation-pressure acceleration in the radial direction :math:`\sum_\text{events}(\Delta a_\text{rad})^2` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``a_rad_r_path_cm`` -- Path-based radial acceleration cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``a_rad_r_path_cov`` -- Path-based radial acceleration covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``a_rad_r_scat`` -- Scattering-based acceleration due to radiation pressure in the radial direction :math:`a_\text{rad,scat}` (spherical coordinates). :dv:`[Units: cm/s^2]`

* ``a_rad_r_scat_e2`` -- Sum of squared event-level contributions to the scattering-based radiation-pressure acceleration in the radial direction :math:`\sum_\text{events}(\Delta a_\text{rad,scat})^2` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``a_rad_r_scat_cm`` -- Scattering-based radial acceleration cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``a_rad_r_scat_cov`` -- Scattering-based radial acceleration covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``F_rad_r_path`` -- Path-based radiation force in the radial direction :math:`F_\text{rad}^\text{path}` (spherical coordinates). :dv:`[Units: g cm/s^2]`

* ``F_rad_r_path_e2`` -- Path-based sum of squared event-level contributions to the radiation force in the radial direction :math:`\sum_\text{events}(\Delta F_\text{rad}^\text{path})^2` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``F_rad_r_path_cm`` -- Path-based radial force cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``F_rad_r_path_cov`` -- Path-based radial force covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``F_rad_r_scat`` -- Scattering-based radiation force in the radial direction :math:`F_\text{rad,scat}` (spherical coordinates). :dv:`[Units: g cm/s^2]`

* ``F_rad_r_scat_e2`` -- Scattering-based sum of squared event-level contributions to the radiation force in the radial direction :math:`\sum_\text{events}(\Delta F_\text{rad,scat})^2` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``F_rad_r_scat_cm`` -- Scattering-based radial force cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``F_rad_r_scat_cov`` -- Scattering-based radial force covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``a_rad_z_path`` -- Path-based acceleration due to radiation pressure in the vertical direction :math:`a_\text{rad}` (cylindrical coordinates). :dv:`[Units: cm/s^2]`

* ``a_rad_z_scat`` -- Scattering-based acceleration due to radiation pressure in the vertical direction :math:`a_\text{rad,scat}` (cylindrical coordinates). :dv:`[Units: cm/s^2]`

.. * ``P_rad`` -- Radiation pressure tensor :math:`P_\text{rad}`. :dv:`[Units: erg/cm^3]`

* ``P_rad_r`` -- Path-based radiation pressure in the radial direction :math:`P_\text{rad}` (spherical and cylindrical coordinates). :dv:`[Units: erg/cm^3]`

* ``P_rad_z`` -- Path-based radiation pressure in the vertical direction :math:`P_\text{rad}` (cylindrical coordinates). :dv:`[Units: erg/cm^3]`

* ``P_rad_rz`` -- Path-based radiation pressure in the shear direction :math:`P_\text{rad}` (cylindrical coordinates). :dv:`[Units: erg/cm^3]`

* ``a_rad_r_grad_u`` -- Packet-level path-based acceleration constructed from the radial energy density gradient :math:`a_{\nabla u}` (spherical coordinates). :dv:`[Units: cm/s^2]`

* ``a_rad_r_grad_u_cm`` -- Radial acceleration cross moment matrix built from the energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``a_rad_r_grad_u_cov`` -- Radial acceleration covariance matrix built from the energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``F_rad_r_grad_u`` -- Path-based radial force constructed from the energy density gradient :math:`F_{\nabla u}` (spherical coordinates). :dv:`[Units: g cm/s^2]`

* ``F_rad_r_grad_u_cm`` -- Radial force cross moment matrix built from the energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``F_rad_r_grad_u_cov`` -- Radial force covariance matrix built from the energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``a_rad_r_div_P`` -- Path-based acceleration constructed from the radial pressure divergence :math:`a_{\nabla \cdot P}` (spherical coordinates). :dv:`[Units: cm/s^2]`

* ``a_rad_r_div_P_cm`` -- Radial acceleration cross moment matrix built from the pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``a_rad_r_div_P_cov`` -- Radial acceleration covariance matrix built from the pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4]`

* ``F_rad_r_div_P`` -- Path-based radial force constructed from the pressure divergence :math:`F_{\nabla \cdot P}` (spherical coordinates). :dv:`[Units: g cm/s^2]`

* ``F_rad_r_div_P_cm`` -- Radial force cross moment matrix built from the pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``F_rad_r_div_P_cov`` -- Radial force covariance matrix built from the pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4]`

* ``P_rad_xx`` -- Path-based radiation pressure in the xx, yy, zz, xy, xz, yz directions :math:`P_\text{rad}` (Cartesian-like coordinates). :dv:`[Units: erg/cm^3]`

* ``trap_cum`` -- Cumulative trapping ratio :math:`t_\text{trap} / t_\text{light}` (spherical coordinates). :dv:`[Units: None]`

* ``trap_x`` -- Frequency-dependent trapping ratio :math:`t_\text{trap} / t_\text{light}` (spherical coordinates). :dv:`[Units: per frequency unit]`

* ``a_rad_x_path`` -- Path-based radiation acceleration per frequency bin (spherical coordinates). :dv:`[Units: cm/s^2 per frequency unit]`

* ``a_rad_x_path_cm`` -- Path-based frequency acceleration cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_path_cov`` -- Path-based frequency acceleration covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_scat`` -- Scattering-based radiation acceleration per frequency bin (spherical coordinates). :dv:`[Units: cm/s^2 per frequency unit]`

* ``a_rad_x_scat_e2`` -- Scattering-based sum of squared event-level acceleration contributions per frequency bin (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_scat_cm`` -- Scattering-based frequency acceleration cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_scat_cov`` -- Scattering-based frequency acceleration covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_grad_u`` -- Frequency-dependent acceleration built from the radial energy density gradient (spherical coordinates). :dv:`[Units: cm/s^2 per frequency unit]`

* ``a_rad_x_grad_u_cm`` -- Frequency acceleration cross moment matrix built from the radial energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_grad_u_cov`` -- Frequency acceleration covariance matrix built from the radial energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_div_P`` -- Frequency-dependent acceleration built from the radial pressure divergence (spherical coordinates). :dv:`[Units: cm/s^2 per frequency unit]`

* ``a_rad_x_div_P_cm`` -- Frequency acceleration cross moment matrix built from the radial pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``a_rad_x_div_P_cov`` -- Frequency acceleration covariance matrix built from the radial pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_path`` -- Path-based radiation force per frequency bin (spherical coordinates). :dv:`[Units: g cm/s^2 per frequency unit]`

* ``F_rad_x_path_cm`` -- Path-based frequency force cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_path_cov`` -- Path-based frequency force covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_scat`` -- Scattering-based radiation force per frequency bin (spherical coordinates). :dv:`[Units: g cm/s^2 per frequency unit]`

* ``F_rad_x_scat_e2`` -- Scattering-based sum of squared event-level force contributions per frequency bin (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_scat_cm`` -- Scattering-based frequency force cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_scat_cov`` -- Scattering-based frequency force covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_grad_u`` -- Frequency-dependent force built from the radial energy density gradient (spherical coordinates). :dv:`[Units: g cm/s^2 per frequency unit]`

* ``F_rad_x_grad_u_cm`` -- Frequency force cross moment matrix built from the radial energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_grad_u_cov`` -- Frequency force covariance matrix built from the radial energy density gradient, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_div_P`` -- Frequency-dependent force built from the radial pressure divergence (spherical coordinates). :dv:`[Units: g cm/s^2 per frequency unit]`

* ``F_rad_x_div_P_cm`` -- Frequency force cross moment matrix built from the radial pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``F_rad_x_div_P_cov`` -- Frequency force covariance matrix built from the radial pressure divergence, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: g^2 cm^2/s^4 per frequency unit^2]`

* ``M_F_src_path`` -- Path-based force multiplier by source :math:`M_F^\text{path}(r_\text{source})` (spherical coordinates). :dv:`[Units: None]`

* ``M_F_src_scat`` -- Scattering-based force multiplier by source :math:`M_F^\text{scat}(r_\text{source})` (spherical coordinates). :dv:`[Units: None]`

* ``M_F_cum_path`` -- Cumulative path-based force multiplier :math:`M_F^\text{path}(<r)` (spherical coordinates). :dv:`[Units: None]`

* ``M_F_cum_scat`` -- Cumulative scattering-based force multiplier :math:`M_F^\text{scat}(<r)` (spherical coordinates). :dv:`[Units: None]`

* ``M_F_cum_grad_u`` -- Cumulative force multiplier derived from the radial energy-density gradient, :math:`-(c/3L)\int_{<r} \nabla u_\text{rad}\,\text{d}V` (spherical coordinates). :dv:`[Units: None]`

* ``M_F_cum_div_P`` -- Cumulative force multiplier derived from the radial pressure divergence, :math:`-(c/L)\int_{<r} \nabla \cdot P_\text{rad}\,\text{d}V` (spherical coordinates). :dv:`[Units: None]`

* ``M_F_x_path`` -- Path-based force multiplier per frequency bin (spherical coordinates). :dv:`[Units: per frequency unit]`

* ``M_F_x_path_cm`` -- Path-based force multiplier frequency cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: per frequency unit^2]`

* ``M_F_x_path_cov`` -- Path-based force multiplier frequency covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: per frequency unit^2]`

* ``M_F_x_scat`` -- Scattering-based force multiplier per frequency bin (spherical coordinates). :dv:`[Units: per frequency unit]`

* ``M_F_x_scat_cm`` -- Scattering-based force multiplier frequency cross moment matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: per frequency unit^2]`

* ``M_F_x_scat_cov`` -- Scattering-based force multiplier frequency covariance matrix, packed as the lower triangle with index :math:`i(i+1)/2+j` (spherical coordinates). :dv:`[Units: per frequency unit^2]`

* ``P_u_cum`` -- Cumulative pressure-to-energy density ratio :math:`P_\text{rad} / u_\text{rad}` in the radial direction (spherical coordinates). :dv:`[Units: None]`

* ``rho2`` -- Density squared :math:`\rho^2`. :dv:`[Units: g^2/cm^6]`

* ``rho2HI`` -- Density squared times the neutral hydrogen fraction :math:`x_\text{HI} \rho^2`. :dv:`[Units: g^2/cm^6]`

* ``rho_star`` -- Stellar density of each cell :math:`\rho_\star`. :dv:`[Units: g/cm^3]`

* ``ion_front`` -- Ionization front. :dv:`[Units: None]`

* ``dx_tot_cumx`` -- Cumulative frequency path length before reaching a given frequency :math:`\sum_{<|x|} \Delta x`. :dv:`[Units: None]`

* ``dl_tot_cumx`` -- Cumulative path length before reaching a given frequency :math:`\sum_{<|x|} \Delta\ell}`. :dv:`[Units: cm]`

* ``l_tot_xesc`` -- Mean path length of photons reaching a given frequency :math:`\sum_{<|x|} \ell / n_\text{esc}`. :dv:`[Units: cm]`

* ``n_scat_xesc`` -- Cumulative number of scatterings before reaching a given frequency :math:`\sum_{<|x|} n_\text{scat}`. :dv:`[Units: None]`

* ``r_xesc`` -- Average escape radius of photons reaching a given frequency :math:`\sum_{<|x|} r / n_\text{esc}`. :dv:`[Units: cm]`

* ``f_xesc`` -- Cumulative number of photons before reaching a given frequency :math:`\sum_{<|x|} n_\text{esc}`. :dv:`[Units: None]`

.. _Star Fields:

Star Fields
-----------

* ``n_stars`` -- Number of stars :math:`n_\text{stars}`. In general, star fields are arrays with this many elements.

* ``r_star`` -- Position coordinates :math:`(x,y,z)`. :dv:`[Units: cm]`

* ``age_star`` -- Star age. :dv:`[Units: Gyr]`

* ``Z_star`` -- Star metallicity :math:`Z_\star`. :dv:`[Units: mass fraction]`

* ``m_star`` -- Stellar mass :math:`m_\star`. :dv:`[Units: Msun]`

* ``m_init_star`` -- Initial stellar mass :math:`m_{\star,0}`. :dv:`[Units: Msun]`

* ``m_massive_star`` -- Current stellar mass contained in massive stars :math:`m_\text{massive}`. :dv:`[Units: Msun]`

* ``L_cont_star`` -- Star continuum band flux :math:`L_\text{cont}`. :dv:`[Units: erg/s/angstrom]`

* ``L_line_star`` -- Star line luminosity :math:`L_\text{line}`. :dv:`[Units: erg/s]`