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Classification of sources is one of the most important tasks in astronomy. Sources detected in one wavelength band, for example using gamma rays, may have several possible associations in other wavebands, or there may be no plausible…

High Energy Astrophysical Phenomena · Physics 2022-04-19 Aakash Bhat , Dmitry Malyshev

We apply and compare various Artificial Neural Network (ANN) and other algorithms for automatic morphological classification of galaxies. The ANNs are presented here mathematically, as non-linear extensions of conventional statistical…

Astrophysics · Physics 2015-06-24 O. Lahav , A. Naim , L. Sodre , M. C. Storrie-Lombardi

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

Based on the DUSTGRAIN-pathfinder suite of simulations, we investigate observational degeneracies between nine models of modified gravity and massive neutrinos. Three types of machine learning techniques are tested for their ability to…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-17 Julian Merten , Carlo Giocoli , Marco Baldi , Massimo Meneghetti , Austin Peel , Florian Lalande , Jean-Luc Starck , Valeria Pettorino

Throughout this paper we present a new method to detect and measure emission lines in J-PAS up to $z = 0.35$. J-PAS will observe $8000$~deg$^2$ of the northern sky in the upcoming years with 56 photometric bands. The release of such amount…

Machine learning techniques that perform morphological classification of astronomical sources often suffer from a scarcity of labelled training data. Here, we focus on the case of supervised deep learning models for the morphological…

Instrumentation and Methods for Astrophysics · Physics 2023-06-16 Lennart Rustige , Janis Kummer , Florian Griese , Kerstin Borras , Marcus Brüggen , Patrick L. S. Connor , Frank Gaede , Gregor Kasieczka , Tobias Knopp , Peter Schleper

Due to the latest advances in technology, telescopes with significant sky coverage will produce millions of astronomical alerts per night that must be classified both rapidly and automatically. Currently, classification consists of…

Instrumentation and Methods for Astrophysics · Physics 2022-08-17 Germán García-Jara , Pavlos Protopapas , Pablo A. Estévez

The aim of this work is to develop a comprehensive method for classifying sources in large sky surveys and we apply the techniques to the VIMOS Public Extragalactic Redshift Survey (VIPERS). Using the optical (u*, g', r', i') and NIR data…

Photometric variability detection is often considered as a hypothesis testing problem: an object is variable if the null-hypothesis that its brightness is constant can be ruled out given the measurements and their uncertainties. Uncorrected…

Instrumentation and Methods for Astrophysics · Physics 2018-01-25 Ilya N. Pashchenko , Kirill V. Sokolovsky , Panagiotis Gavras

(Abridged) Many classes of active galactic nuclei (AGN) have been defined entirely throughout optical wavelengths while the X-ray spectra have been very useful to investigate their inner regions. However, optical and X-ray results show many…

Machine learning techniques are utilised in several areas of astrophysical research today. This dissertation addresses the application of ML techniques to two classes of problems in astrophysics, namely, the analysis of individual…

Astrophysics · Physics 2009-01-06 N. Daniel Kumar

We present The Machine, an artificial neural network (ANN) capable of differentiating between the numbers of Gaussian components needed to describe the emission lines of Integral Field Spectroscopic (IFS) observations. Here we show the…

Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a…

Instrumentation and Methods for Astrophysics · Physics 2016-06-29 J. Elliott , R. S. de Souza , A. Krone-Martins , E. Cameron , E. E. O. Ishida , J. Hilbe

Data mining is an important and challenging problem for the efficient analysis of large astronomical databases and will become even more important with the development of the Global Virtual Observatory. In this study, learning vector…

Astrophysics · Physics 2009-11-10 Yanxia Zhang , Yongheng Zhao

Reliable, versatile galaxy activity diagnostics are essential for understanding galaxy evolution. Traditional methods frequently necessitate extensive preprocessing, such as starlight subtraction and emission line deblending (e.g.,…

Astrophysics of Galaxies · Physics 2026-02-25 C. Daoutis , A. Zezas , E. Kyritsis , K. Kouroumpatzakis , P. Bonfini

We describe an Artificial Neural Network (ANN) approach to classification of galaxy images and spectra. ANNs can replicate the classification of galaxy images by a human expert to the same degree of agreement as that between two human…

Astrophysics · Physics 2007-05-23 Ofer Lahav

Based on the Sloan Digital Sky Survey Data Release 5 Galaxy Sample, we explore photometric morphology classification and redshift estimation of galaxies using photometric data and known spectroscopic redshifts. An unsupervised method,…

Astrophysics · Physics 2009-11-13 Yanxia Zhang , Lili Li , Yongheng Zhao

Axion-like particles (ALPs) appear in various new physics models with spontaneous global symmetry breaking. When the ALP mass is in the range of MeV to GeV, the cosmology and astrophysics bounds are so far quite weak. In this work, we…

High Energy Physics - Phenomenology · Physics 2021-12-08 Jie Ren , Daohan Wang , Lei Wu , Jin Min Yang , Mengchao Zhang

Within scientific and real life problems, classification is a typical case of extremely complex tasks in data-driven scenarios, especially if approached with traditional techniques. Machine Learning supervised and unsupervised paradigms,…

Instrumentation and Methods for Astrophysics · Physics 2018-07-13 Giuseppe Angora , Massimo Brescia , Stefano Cavuoti , Giuseppe Riccio , Maurizio Paolillo , Thomas H. Puzia

Active Galactic Nuclei (AGN) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight, yet the specific inclinations of all but a few AGN are generally…

Astrophysics of Galaxies · Physics 2015-06-18 T. C. Fischer , D. M. Crenshaw , S. B. Kraemer , H. R. Schmitt , T. J. Turner