lenstronomy release 1.9.0

[Simon Birrer]

Dear lenstronomy community,

I am pleased to announce lenstronomy version 1.9.0 is released on PyPi. The release follows the latest changes on the main branch of lenstronomy.

The notebooks are updated/tested with this latest release.

The new release contain mostly minor changes, but two aspects that are not fully backwards compatible, hence moving from 1.8.X -> 1.9.0.

One is concerning the definition of the half-light radius of the elliptical Sersic profile (SERSIC_ELLIPSE). Previous definition was along the semi-major axis. This definition was the same as for Galfit, but different than all other elliptical light definitions in lenstronomy. In this release, we changed the default half-light radius definition R_sersic to be the product average of semi-major and semi-minor axis. This updated definition has several advantages:

- half-light radius measurement not impacted by uncertainty in ellipticity (or potential bias)

- less covariances between ellipticity parameters and half-light radius

- elliptical transformation preserve total flux

- consistent definition with all other lenstronomy light profiles

If you want to keep the old definition for your models, you can do so by adding a flag to the global lenstronomy configuration with

in the ‘conventions’ section in config file with  ’service_major_asix’

https://github.com/sibirrer/lenstronomy/blob/main/lenstronomy/Conf/conf_default.yaml

(you can set a new configuration file in the directory $ ~/.conf/lenstronomy/config.yaml)

See also https://lenstronomy.readthedocs.io/en/latest/installation.html

This change is long overdue from my side and sorry for the inconveniences in case of upgrading.

Another (minor) change is that in the CONVERGENCE lens model the parameter ‘kappa_ext’ has been changed to ‘kappa’, reflecting the more general usage of this profile type.

Detailed release notes are bellow. The lenstronomy extension notebooks are tested and run with this latest version.

Please let me know if you have questions and/or encounter problems.

Best,

Simon

lenstronomy v1.9.0 release notes:

- Configuration:

- re-design of reading global configurations

- added ‘conventions’ section in config file with  ’service_major_asix’

- GalKin module:

- difference in 3d rendering 

- improved accuracy in calculation and testing (thanks to Matt Gomer)

- LensModel module:

- multi-plane functionality in separate sub-package

- ‘CONVERGENCE’ model parameter renamed ‘kappa_ext’ -> ‘kappa’

- LightModel module:

- Sersic radius ‘R_sersic’ changed from semi-major axis definition to product average of semi-major and semi-minor axis

- possibility to keep old ‘R_sersic’ convention with argument ’service_major_asix’: True in config file

- Plotting:

- lens_model_plot redesigned and more options for user

minor documentation and code improvements

Simon Birrer

----------------

Kavli Postdoctoral Fellow

Stanford | KIPAC

Email: sibi...@stanford.edu

Web: https://sibirrer.github.io