Galaxies (skypy.galaxies)

Introduction

Galaxy Properties

What follows are the physical properties of galaxies simulated by SkyPy, and the available models for each individual property.

Luminosity

The following models are found in the skypy.galaxies.luminosity package.

schechter_lf_magnitude

Sample magnitudes from a Schechter luminosity function.

Morphology

The following models are found in the skypy.galaxies.morphology package.

angular_size	Angular size of a galaxy.
beta_ellipticity	Galaxy ellipticities sampled from a reparameterized beta distribution.
early_type_lognormal_size	Lognormal size distribution for early-type galaxies.
late_type_lognormal_size	Lognormal size distribution for late-type galaxies.
linear_lognormal_size	Lognormal size distribution with linear mean.
ryden04_ellipticity	Ellipticity distribution of Ryden (2004).

Redshift

The following models are found in the skypy.galaxies.redshift package.

redshifts_from_comoving_density	Sample redshifts from a comoving density function.
schechter_lf_redshift	Sample redshifts from Schechter luminosity function.
schechter_smf_redshift	Sample redshifts from Schechter function.
smail	Redshifts following the Smail et al. (1994) model.

Spectrum

The following models are found in the skypy.galaxies.spectrum package.

SkyPy uses the speclite package for photometric calculations. Some of the following functions take the names of photometric filters as an input parameter. Users can choose from the available Speclite Filters following the naming syntax described in speclite.filters.load_filters, or create their own named speclite.filters.FilterResponse.

dirichlet_coefficients	Dirichlet-distributed SED coefficients.
KCorrectTemplates	Galaxy spectra from kcorrect templates.
kcorrect	KCorrectTemplates using kcorrect smoothed templates.

Stellar mass

The following models are found in the skypy.galaxies.stellar_mass package.

schechter_smf_mass

Stellar masses following the Schechter mass function [R04329ffbeb03-1].

Velocity dispersion

The following models are found in the skypy.galaxies.velocity_dispersion package.

schechter_vdf

Sample velocity dispersion of elliptical galaxies in the local universe following a Schecter function.

Reference/API

skypy.galaxies Package

This module contains methods that model the intrinsic properties of galaxy populations.

Functions

schechter_lf(redshift, M_star, phi_star, ...)	Sample redshifts and magnitudes from a Schechter luminosity function.
schechter_smf(redshift, m_star, phi_star, ...)	Sample redshifts and stellar masses from a Schechter mass function.

skypy.galaxies.luminosity Module

Models of galaxy luminosities.

Functions

schechter_lf_magnitude(redshift, M_star, ...)

Sample magnitudes from a Schechter luminosity function.

skypy.galaxies.morphology Module

Galaxy morphology module.

This module provides facilities to sample the sizes and ellipticities of galaxies.

Functions

angular_size(physical_size, redshift, cosmology)	Angular size of a galaxy.
beta_ellipticity(e_ratio, e_sum[, size])	Galaxy ellipticities sampled from a reparameterized beta distribution.
early_type_lognormal_size(magnitude, a, b, ...)	Lognormal size distribution for early-type galaxies.
late_type_lognormal_size(magnitude, alpha, ...)	Lognormal size distribution for late-type galaxies.
linear_lognormal_size(magnitude, a_mu, b_mu, ...)	Lognormal size distribution with linear mean.
ryden04_ellipticity(mu_gamma, sigma_gamma, ...)	Ellipticity distribution of Ryden (2004).

skypy.galaxies.redshift Module

Galaxy redshift module.

This module provides facilities to sample galaxy redshifts using a number of models.

Functions

redshifts_from_comoving_density(redshift, ...)	Sample redshifts from a comoving density function.
schechter_lf_redshift(redshift, M_star, ...)	Sample redshifts from Schechter luminosity function.
schechter_smf_redshift(redshift, m_star, ...)	Sample redshifts from Schechter function.
smail(z_median, alpha, beta[, size])	Redshifts following the Smail et al. (1994) model.

skypy.galaxies.spectrum Module

Galaxy spectrum module.

Functions

dirichlet_coefficients(redshift, alpha0, alpha1)

Dirichlet-distributed SED coefficients.

Classes

KCorrectTemplates([hdu])

Galaxy spectra from kcorrect templates.

Variables

kcorrect

KCorrectTemplates using kcorrect smoothed templates.

Class Inheritance Diagram

skypy.galaxies.stellar_mass Module

Models of galaxy stellar mass.

Functions

schechter_smf_mass(redshift, alpha, m_star, ...)

Stellar masses following the Schechter mass function [R04329ffbeb03-1].

skypy.galaxies.velocity_dispersion Module

Models of galaxy velocity dispersion.

Functions

schechter_vdf(alpha, beta, vd_star, vd_min, ...)

Sample velocity dispersion of elliptical galaxies in the local universe following a Schecter function.