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arXiv · 2303.11691

A versatile classification tool for galactic activity using optical and infrared colors

Elias Kyritsis·Charalampos Daoutis·Andreas Zezas·Konstantinos Kouroumpatzakis
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Abstract

We use the Random Forest (RF) algorithm to develop a tool for automated activity classification of galaxies into 5 different classes: Star-forming (SF), AGN, LINER, Composite, and Passive. We train the algorithm on a combination of mid-IR (WISE) and optical photometric data while the true labels (activity classes) are based on emission line ratios. Our classifier is built to be redshift-agnostic and it is applicable to objects up to z $\sim$0.1. It reaches a completeness $>$80 % for SF and Passive galaxies, and $\sim$60 % for AGN. Applying it to an all-sky galaxy catalog (HECATE) reveals a large population of low-luminosity AGNs outside the AGN locus in the standard mid-IR diagnostics.

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Elias Kyritsis, Charalampos Daoutis, Andreas Zezas, Konstantinos Kouroumpatzakis. 2023-03-21. A versatile classification tool for galactic activity using optical and infrared colors. https://arxiv.org/abs/2303.11691

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