Galaxy / Tracer#

Galaxy and Galaxies model individual galaxies with light and mass profiles at a given redshift. Tracer groups galaxies by redshift into planes and performs multi-plane gravitational lensing ray-tracing, computing lensed images, convergence, deflection angles, magnification, critical curves, and caustics.

MassField holds the mass of everything outside the modelled system — an external shear, a mass sheet, an external potential — at its own redshift and with no light of its own; pass a list of them as Tracer(galaxies=..., fields=[field]) and each is placed in the plane at its redshift, contributing its mass to every lensing calculation while every per-galaxy surface still sees galaxies alone. Attaching these components to a Galaxy instead remains fully supported. For one field, Tracer(galaxies=..., fields=field) is also accepted; tracer.fields is always stored as a list.

`Galaxy`	Class representing a galaxy, which is composed of attributes used for fitting galaxies (e.g. light profiles, mass profiles, pixelizations, etc.).
`Galaxies`	A collection of galaxies, used to perform operations on the galaxies as a group.
`MassField`	Class representing the external mass field at a given redshift.
`Tracer`	Performs gravitational lensing ray-tracing calculations based on an input list of galaxies and a cosmology.

To treat the redshift of a galaxy as a free parameter in a model, the Redshift object must be used.

This is because PyAutoFit (which handles model-fitting), requires all parameters to be a Python class.

The Redshift object does not need to be used for general PyAutoGalaxy use.

Redshift

Class used when assigning a redshift to a Galaxy object.

Galaxy Catalogues (CSV)#

Load many galaxies from a y, x, luminosity CSV catalogue — the input format of the scaling-relation galaxy tier used at multi-galaxy, group and cluster scale (see the multi_galaxy, group and cluster packages of the autolens_workspace). galaxy_table_from_csv reads the catalogue; the two *_from_csv_tables functions build instances or model components from it.

`galaxy_table_from_csv`(file_path)	Load a galaxy population from a CSV with columns `y, x, luminosity, redshift?`.
`galaxies_from_csv_tables`(*tables)	Combine one or more family tables into concrete `Galaxy` instances.
`galaxy_af_models_from_csv_tables`(*tables)	Combine one or more family tables into `af.Model[Galaxy]` instances.