Enhancing weak lensing redshift distribution characterization by optimizing the Dark Energy Survey Self-Organizing Map Photo-z method

Campos, A., Yin, B., Dodelson, S., Amon, A., Alarcon, A. and Harrison, I. ORCID: https://orcid.org/0000-0002-4437-0770 2026. Enhancing weak lensing redshift distribution characterization by optimizing the Dark Energy Survey Self-Organizing Map Photo-z method. The Open Journal of Astrophysics 9 10.33232/001c.165871

Full text not available from this repository.

Abstract

Characterization of the redshift distribution of ensembles of galaxies is pivotal for large scale structure cosmological studies. In this work, we focus on improving the Self-Organizing Map (SOM) methodology for photometric redshift estimation (SOMPZ), specifically in anticipation of the Dark Energy Survey Year 6 (DES Y6) data. This data set, featuring deeper and fainter galaxies than DES Year 3 (DES Y3), demands adapted techniques to ensure accurate recovery of the underlying redshift distribution. We investigate three strategies for enhancing the existing SOM-based approach used in DES Y3: 1) Replacing the Y3 SOM algorithm with one tailored for redshift estimation challenges; 2) Incorporating g-band flux information to refine redshift estimates (i.e. using griz fluxes as opposed to only riz); 3) Augmenting redshift data for galaxies where available. These methods are applied to DES Y3 data, and results are compared to the Y3 fiducial ones. Our analysis indicates significant improvements with the first two strategies, notably reducing the overlap between redshift bins. By combining strategies 1 and 2, we have successfully managed to reduce redshift bin overlap in DES Y3 by up to 66%. Conversely, the third strategy, involving the addition of redshift data for selected galaxies as an additional feature in the method, yields inferior results and is abandoned. Our findings contribute to the advancement of weak lensing redshift characterization and lay the groundwork for better redshift characterization in DES Year 6 and future stage IV surveys, like the Rubin Observatory.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Physical, Chemical & Environmental Sciences
Additional Information:	Full author list at DOI
Last Modified:	02 Sep 2026 14:15
URI:	https://orca.cardiff.ac.uk/id/eprint/189354

Actions (repository staff only)

Edit Item