trident.ion_balance.calculate_ion_fraction

trident.ion_balance.calculate_ion_fraction(ion, density, temperature, redshift, ionization_table=None)[source]

Calculate ion fraction at specified density, temperature, and redshift

This simple function interpolates ion fraction values from the relevant ion_balance data table for arrays of density, temperature, and redshift values.

Users can specify individual coordinates in density, temperature, and redshift or N-sized arrays to derived values in parallel.

Ion fractions are calculated assuming collisional ionization and photoionization in the optically thin limit from a redshift-dependent metagalactic ionizing background using the ionization_table specified.

Trilinear interpolation is assumed across density, temperature, and redshift.

Parameters

Ion:

string

The desired ion following the form: “<element> <ionization_state>” Examples: “H I”, “C II”, “Mg II”

Density:

float or array of floats

Gas density in the form of hydrogen number density cm$**{-3}$

Temperature:

float or array of floats

Gas temperature in kelvin

Redshift:

float or array of floats

Redshift at which to assume the metagalactic UV background

Ionization_table:

string, optional

Path to an appropriately formatted HDF5 table that can be used to compute the ion fraction as a function of density, temperature, metallicity, and redshift. When set to None, it uses the table specified in ~/.trident/config Default: None

Example

To calculate the ion fraction of Mg II for gas with hydrogen number density 1e-2 cm**-3 and redshift 0.25 and temperatures 1e4K:

>>> import trident
>>> trident.calculate_ion_fraction('Mg II', 1e-2, 1e4, 0.25)