lfkit.api.luminosity_function module#

Public luminosity function interface.

This module provides the user-facing LuminosityFunction API for evaluating luminosity functions in absolute- or apparent magnitude space.

The class stores luminosity function model state and exposes grouped API namespaces for related calculations. Low-level numerical and photometric work remains in the function-based lfkit.photometry modules.

class lfkit.api.luminosity_function.LuminosityFunction(*, model, parameters, meta=None)[source]#

Bases: object

User-facing wrapper for luminosity function evaluation.

Parameters:

  • model (str) – Name of the luminosity function model.

  • parameters (Mapping[str, object]) – Model parameters passed to the underlying LF function.

  • meta (Mapping[str, object] | None) – Optional metadata describing the LF source or calibration.

static available_from_m_models()[source]#

Return models that support apparent magnitude evaluation.

Return type:

list[str]

static available_models()[source]#

Return luminosity function model names available through the API.

Return type:

list[str]

static available_parameter_models()[source]#

Return available LF parameter evolution models.

Return type:

dict[str, list[str]]

classmethod double_schechter(*, phi_star, m_star, alpha, beta, m_transition, meta=None)[source]#

Create a double-power-law Schechter luminosity function.

Parameters:

  • phi_star (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Normalization of the luminosity function.

  • m_star (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Characteristic absolute magnitude.

  • alpha (float) – Bright-end or main Schechter slope.

  • beta (float) – Additional slope controlling the second power-law component.

  • m_transition (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Transition magnitude for the second component.

  • meta (Mapping[str, object] | None) – Optional metadata describing the LF source or calibration.

Returns:

Luminosity-function API object using the double Schechter model.

Return type:

LuminosityFunction

classmethod evolving_schechter(*, phi_model='linear_p', phi_kwargs=None, m_star_model='linear_q', m_star_kwargs=None, alpha_model='constant', alpha_kwargs=None, meta=None)[source]#

Create a redshift-evolving Schechter luminosity function.

Parameters:

  • phi_model (str) – Parameter model used for the normalization evolution.

  • phi_kwargs (Mapping[str, float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]] | None) – Keyword arguments for the normalization model.

  • m_star_model (str) – Parameter model used for characteristic-magnitude evolution.

  • m_star_kwargs (Mapping[str, float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]] | None) – Keyword arguments for the characteristic-magnitude model.

  • alpha_model (str) – Parameter model used for faint-end-slope evolution.

  • alpha_kwargs (Mapping[str, float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]] | None) – Keyword arguments for the faint-end-slope model.

  • meta (Mapping[str, object] | None) – Optional metadata describing the LF source or calibration.

Returns:

Luminosity-function API object using an evolving Schechter model.

Return type:

LuminosityFunction

parameters(z)[source]#

Evaluate evolving Schechter parameters at redshift.

Parameters:

z (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Redshift values where the evolving LF parameters are evaluated.

Returns:

Tuple containing phi_star(z), m_star(z), and alpha(z).

Return type:

tuple[ndarray[tuple[Any, …], dtype[float64]], ndarray[tuple[Any, …], dtype[float64]], ndarray[tuple[Any, …], dtype[float64]]]

phi(absolute_mag, z=None)[source]#

Evaluate the luminosity function in absolute magnitude space.

Parameters:

  • absolute_mag (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Absolute magnitude values where the LF is evaluated.

  • z (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]] | None) – Redshift or conditional-coordinate values. Required for evolving and conditional models.

Returns:

Luminosity-function values evaluated at the input magnitudes.

Return type:

ndarray[tuple[Any, …], dtype[float64]]

phi_from_m(cosmo_obj, z, apparent_mag, *, h=None, corrections=None)[source]#

Evaluate the luminosity function from apparent magnitudes.

Apparent magnitudes are converted to absolute magnitudes using the supplied cosmology, optional reduced Hubble parameter, and optional k- and e-correction model.

Parameters:

  • cosmo_obj (Any) – Cosmology object used for distance-modulus conversion.

  • z (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Redshift values.

  • apparent_mag (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Apparent magnitude values.

  • h (float | None) – Optional reduced Hubble parameter used in the magnitude conversion.

  • corrections (object | None) – Optional object providing k-correction and e-correction values.

Returns:

Luminosity-function values evaluated from apparent magnitudes.

Return type:

ndarray[tuple[Any, …], dtype[float64]]

static register_alpha_model(name, model, *, overwrite=False)[source]#

Register an alpha evolution model.

Parameters:

  • name (str) – Name used to identify the model.

  • model (Callable[[...], ndarray[tuple[Any, ...], dtype[float64]]]) – Callable evaluating alpha(z).

  • overwrite (bool) – If True, replace an existing model with the same name.

Return type:

None

static register_m_star_model(name, model, *, overwrite=False)[source]#

Register an M-star evolution model.

Parameters:

  • name (str) – Name used to identify the model.

  • model (Callable[[...], ndarray[tuple[Any, ...], dtype[float64]]]) – Callable evaluating M_star(z).

  • overwrite (bool) – If True, replace an existing model with the same name.

Return type:

None

static register_phi_star_model(name, model, *, overwrite=False)[source]#

Register a phi-star evolution model.

Parameters:

  • name (str) – Name used to identify the model.

  • model (Callable[[...], ndarray[tuple[Any, ...], dtype[float64]]]) – Callable evaluating phi_star(z).

  • overwrite (bool) – If True, replace an existing model with the same name.

Return type:

None

classmethod schechter(*, phi_star, m_star, alpha, meta=None)[source]#

Create a standard Schechter luminosity function.

Parameters:

  • phi_star (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Normalization of the luminosity function.

  • m_star (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Characteristic absolute magnitude.

  • alpha (float | Sequence[float] | ndarray[tuple[Any, ...], dtype[float64]]) – Faint-end slope.

  • meta (Mapping[str, object] | None) – Optional metadata describing the LF source or calibration.

Returns:

Luminosity-function API object using the standard Schechter model.

Return type:

LuminosityFunction