autolens.analysis.model_util.mge_point_model_from#

mge_point_model_from(pixel_scales, total_gaussians=10, centre=(0.0, 0.0), sigma_min=0.01)[source]#

Construct a Multi-Gaussian Expansion (MGE) model for a compact or unresolved point-like component (e.g. a nuclear starburst, AGN, or unresolved bulge).

The model is composed of total_gaussians linear Gaussians whose sigma values are logarithmically spaced between sigma_min and twice the pixel scale. All Gaussians share the same centre and ellipticity components, keeping the parameter count low while capturing a realistic PSF-convolved point source.

Parameters:

  • pixel_scales (float) – The pixel scale of the image in arcseconds per pixel. The maximum Gaussian width is set to 2 * pixel_scales so that the model is compact relative to the resolution of the data.

  • total_gaussians (int) – Number of Gaussian components in the basis.

  • centre (Tuple[float, float]) – (y, x) centre of the point source in arc-seconds. A ±0.1 arcsecond uniform prior is placed on each coordinate.

  • sigma_min (float) – The smallest Gaussian width (sigma) in arcseconds, which sets the lower end of the log-spaced sigma values. Defaults to 0.01. Increase it (e.g. to a tenth of the pixel scale) to stop the basis wasting components on scales the data cannot resolve.

Returns:

An autofit.Model wrapping a Basis of linear Gaussians.

Return type:

af.Model