Morphological analysis of well-resolved galaxies
Abstract
We have developed a Python-based tool for the detailed morphological analysis of well-resolved galaxies. Our method removes foreground stars, determines the position and inclination angles, fits structural components for spiral galaxies, models the radial light profile, and transforms the image into polar coordinates to produce a Theta–log(r) representation. We then measure the opening angles of the spiral arms and analyze the power spectrum and flocculence of the galactic disk to determine the strength of the spiral structure.
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LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Morphological analysis of well-resolved galaxies Tamás KOVÁCS joint work with Zsolt Frei and Balázs Pinczel Eötvös University, Budapest, Hungary
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Introduction & Motivation ● Galaxy morphology encodes structure and evolution (Conselice, 2004) ● Automatic methods required for massive surveys (LSST, ROMAN) ● Methods for bulge-disk decomposition, spiral arm detection, and morphological parameters ● LSST will collect billions of galaxy image (Ivezic, 2019)
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Implemented Methodology ● Deprojection of galaxies ● Bulge-disk decomposition and star removal ● Spiral arm detection via Fourier modes (Frei, 1999) ● Morphological descriptors for classification
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Implemented Methodology ● Deprojection of galaxies image moments vs. silhouettes brightness pixels
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Implemented Methodology ● Bulge-disk decomposition and star removal Radial profile R (arcsec)
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Implemented Methodology ● Spiral arm detection via Fourier modes ln (R) azimuth angle azimuth angle intensity mode P Frei, 1999
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Implemented Methodology ● Morphological descriptors for classification Nonparametric measures (CAS) & PCA Chantavat, arXiv:2403.05003v1
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Application to Rubin data ● LSST: Automated classification essential ● Methods implemented scale to large surveys ● Enables: – Statistical galaxy morphology studies – Evolution of structure over cosmic time – Training sets for machine learning models
LSST@Europe7 | Poznań, Poland | September 15th-19th, 2025 Glossary & Acronyms Summary and future work ● Implemented methods in Python ● Robust morphological descriptors confirmed ● PCA highlights key correlated parameters ● LSST will benefit greatly from automation Next steps: scaling + GPU + ML integration