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We use machine learning techniques to investigate their performance in classifying active galactic nuclei (AGNs), including X-ray selected AGNs (XAGNs), infrared selected AGNs (IRAGNs), and radio selected AGNs (RAGNs). Using known physical…

Astrophysics of Galaxies · Physics 2021-10-26 Yu-Yen Chang , Bau-Ching Hsieh , Wei-Hao Wang , Yen-Ting Lin , Chen-Fatt Lim , Yoshiki Toba , Yuxing Zhong , Siou-Yu Chang

We present a machine learning model to classify Active Galactic Nuclei (AGN) and galaxies (AGN-galaxy classifier) and a model to identify type 1 (optically unabsorbed) and type 2 (optically absorbed) AGN (type 1/2 classifier). We test…

Astrophysics of Galaxies · Physics 2021-12-08 Serena Falocco , Francisco J. Carrera , Josefin Larsson

We develop a new diagnostic method to classify galaxies into AGN hosts, star-forming galaxies, and absorption-dominated galaxies by combining the [O III]/Hbeta ratio with rest-frame U-B color. This can be used to robustly select AGNs in…

In the absence of the two emission lines H$\alpha$ and [NII] (6584\AA) in a BPT diagram, we show that other spectral information is sufficiently informative to distinguish AGN galaxies from star-forming galaxies. We use pattern recognition…

Astrophysics of Galaxies · Physics 2018-06-06 Hossen Teimoorinia , Jared Keown

We present an application of a particular machine-learning method (Boosted Decision Trees, BDTs using AdaBoost) to separate stars and galaxies in photometric images using their catalog characteristics. BDTs are a well established machine…

Instrumentation and Methods for Astrophysics · Physics 2015-04-28 Ignacio Sevilla-Noarbe , Penélope Etayo-Sotos

With upcoming all sky surveys such as LSST poised to generate a deep digital movie of the optical sky, variability-based AGN selection will enable the construction of highly-complete catalogs with minimum contamination. In this study, we…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-27 Yumi Choi , Robert R. Gibson , Andrew C. Becker , Željko Ivezić , Andrew J. Connolly , Chelsea L. MacLeod , John J. Ruan , Scott F. Anderson

We have applied ClassX, an oblique decision tree classifier optimized for astronomical analysis, to the homogeneous multicolor imaging data base of the Sloan Digital Sky Survey (SDSS), training the software on subsets of SDSS objects whose…

Astrophysics · Physics 2008-11-26 A. A. Suchkov , R. J. Hanisch , Bruce Margon

Most existing star-galaxy classifiers depend on the reduced information from catalogs, necessitating careful data processing and feature extraction. In this study, we employ a supervised machine learning method (GoogLeNet) to automatically…

Astrophysics of Galaxies · Physics 2024-09-23 Shiliang Zhang , Guanwen Fang , Jie Song , Ran Li , Yizhou Gu , Zesen Lin , Chichun Zhou , Yao Dai , Xu Kong

Identifying Active Galactic Nuclei (AGNs) through their X-ray emission is efficient, but necessarily biased against X-ray-faint objects. We aim to characterize this bias by comparing X-ray-selected AGNs to the ones identified through…

We employ the XGBoost machine learning (ML) method for the morphological classification of galaxies into two (early-type, late-type) and five (E, S0--S0a, Sa--Sb, Sbc--Scd, Sd--Irr) classes, using a combination of non-parametric…

In Astrophysics, the identification of candidate Globular Clusters through deep, wide-field, single band HST images, is a typical data analytics problem, where methods based on Machine Learning have revealed a high efficiency and…

Instrumentation and Methods for Astrophysics · Physics 2017-10-12 Giuseppe Angora , Massimo Brescia , Giuseppe Riccio , Stefano Cavuoti , Maurizio Paolillo , Thomas H. Puzia

In this paper we discuss an application of machine learning based methods to the identification of candidate AGN from optical survey data and to the automatic classification of AGNs in broad classes. We applied four different machine…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-14 Stefano Cavuoti , Massimo Brescia , Raffaele D'Abrusco , Giuseppe Longo , Maurizio Paolillo

Aims. Traditional star-galaxy classification techniques often rely on feature estimation from catalogues, a process susceptible to introducing inaccuracies, thereby potentially jeopardizing the classification's reliability. Certain…

Instrumentation and Methods for Astrophysics · Physics 2023-12-20 F. Stoppa , S. Bhattacharyya , R. Ruiz de Austri , P. Vreeswijk , S. Caron , G. Zaharijas , S. Bloemen , G. Principe , D. Malyshev , V. Vodeb , P. J. Groot , E. Cator , G. Nelemans

This paper explores the application of machine learning methods for classifying astronomical sources using photometric data, including normal and emission line galaxies (ELGs; starforming, starburst, AGN, broad line), quasars, and stars. We…

We introduce a novel machine learning dataset tailored for the classification of bent radio active galactic nuclei (AGN) in astronomical observations. Bent radio AGN, distinguished by their curved jet structures, provide critical insights…

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…

Astrophysics of Galaxies · Physics 2023-03-22 Elias Kyritsis , Charalampos Daoutis , Andreas Zezas , Konstantinos Kouroumpatzakis

We have employed a reliable technique of classification of Active Galactic Nuclei (AGN) based on the fit of well-sampled spectral energy distributions (SEDs) with a complete set of AGN and starburst galaxy templates. We have compiled…

Context. Active galactic nuclei (AGNs) and star forming galaxies (SFGs) are the primary sources of extragalactic radio sky. But it is difficult to distinguish the radio emission produced by AGNs from that by SFGs, especially when the radio…

Astrophysics of Galaxies · Physics 2025-09-17 Xu-Liang Fan , Jie Li

In order to perform a more complete census of active galactic nuclei (AGN) in the local Universe, we investigate the use of the HeII~$\lambda 4685$ emission line diagnostic diagram by Shirazi & Brinchmann (2012) in addition to the standard…

Astrophysics of Galaxies · Physics 2017-01-25 Rudolf Bär , Anna K. Weigel , Lia F. Sartori , Kyuseok Oh , Michael Koss , Kevin Schawinski

The sensitivity of a search for sources of TeV neutrinos can be improved by grouping potential sources together into generic classes in a procedure that is known as source stacking. In this paper, we define catalogs of Active Galactic…

Astrophysics · Physics 2008-11-26 A. Achterberg et al.
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