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We investigate the physical nature of active galactic nuclei (AGNs) using machine learning (ML) tools. We show that the redshift, $z$, bolometric luminosity, $L_{\rm Bol}$, central mass of the supermassive black hole (SMBH), $M_{\rm BH}$,…

Astrophysics of Galaxies · Physics 2024-05-17 Sarah Mechbal , Markus Ackermann , Marek Kowalski

We present the result of a spectroscopic campaign targeting Active Galactic Nucleus (AGN) candidates selected using a novel unsupervised machine-learning (ML) algorithm trained on optical and mid-infrared (mid-IR) photometry. AGN candidates…

Astrophysics of Galaxies · Physics 2024-02-09 Raphael E. Hviding , Kevin N. Hainline , Andy D. Goulding , Jenny E. Greene

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

Machine-learning (ML) algorithms will play a crucial role in studying the large datasets delivered by new facilities over the next decade and beyond. Here, we investigate the capabilities and limits of such methods in finding galaxies with…

Instrumentation and Methods for Astrophysics · Physics 2019-08-22 Andreas L. Faisst , Abhishek Prakash , Peter L. Capak , Bomee Lee

Active Galactic Nuclei (AGN) are relevant sources of radiation that might have helped reionising the Universe during its early epochs. The super-massive black holes (SMBHs) they host helped accreting material and emitting large amounts of…

Astrophysics of Galaxies · Physics 2021-11-02 Rodrigo Carvajal , Israel Matute , José Afonso , Stergios Amarantidis , Davi Barbosa , Pedro Cunha , Andrew Humphrey

(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…

The Active Galactic Nuclei (AGN) glossary is vast and complex. Depending on selection method, observing wavelength, and brightness, AGNs are assigned distinct labels, yet the relationship between different selection methods and the…

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

A novel application of machine-learning (ML) based image processing algorithms is proposed to analyze an all-sky map (ASM) obtained using the Fermi Gamma-ray Space Telescope. An attempt was made to simulate a one-year ASM from a…

High Energy Astrophysical Phenomena · Physics 2021-06-02 Shogo Sato , Jun Kataoka , Soichiro Ito , Jun'ichi Kotoku , Masato Taki , Asuka Oyama , Takaya Toyoda , Yuki Nakamura , Marino Yamamoto

Measuring the redshift of active galactic nuclei (AGNs) requires the use of time-consuming and expensive spectroscopic analysis. However, obtaining redshift measurements of AGNs is crucial as it can enable AGN population studies, provide…

Context. The classification of active galactic nuclei (AGNs) is a challenge in astrophysics. Variability features extracted from light curves offer a promising avenue for distinguishing AGNs and their subclasses. This approach would be very…

The spectra of Active Galactic Nuclei (AGNs) are often characterized by a wealth of emission lines with different profiles and intensity ratios that led to a complicated classification. Their electro-magnetic radiation spans more than 10…

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

Given a grayscale photograph, the colorization system estimates a visually plausible colorful image. Conventional methods often use semantics to colorize grayscale images. However, in these methods, only classification semantic information…

Computer Vision and Pattern Recognition · Computer Science 2020-11-24 Yuzhi Zhao , Lai-Man Po , Kwok-Wai Cheung , Wing-Yin Yu , Yasar Abbas Ur Rehman

The use of Artificial Neural Networks (ANNs) as a classifier of digital spectra is investigated. Using both simulated and real data, it is shown that neural networks can be trained to discriminate between the spectra of different classes of…

Astrophysics · Physics 2021-10-13 Daya M. Rawson , Jeremy Bailey , Paul J. Francis

Deep neural networks (DNNs) are being increasingly used to make predictions from functional magnetic resonance imaging (fMRI) data. However, they are widely seen as uninterpretable "black boxes", as it can be difficult to discover what…

Machine Learning · Computer Science 2020-12-18 Patrick McClure , Dustin Moraczewski , Ka Chun Lam , Adam Thomas , Francisco Pereira

Precisely localising solar Active Regions (AR) from multi-spectral images is a challenging but important task in understanding solar activity and its influence on space weather. A main challenge comes from each modality capturing a…

Computer Vision and Pattern Recognition · Computer Science 2024-07-22 Majedaldein Almahasneh , Adeline Paiement , Xianghua Xie , Jean Aboudarham

The artificial neural network (ANN) is a well-established mathematical technique for data prediction, based on the identification of correlations and pattern recognition in input training sets. We present the application of ANNs to predict…

Astrophysics of Galaxies · Physics 2014-05-05 Hossein Teimoorinia , Sara L. Ellison

Saliency prediction can benefit from training that involves scene understanding that may be tangential to the central task; this may include understanding places, spatial layout, objects or involve different datasets and their bias. One can…

Computer Vision and Pattern Recognition · Computer Science 2019-03-12 Sen Jia , Neil D. B. Bruce

Active galactic nuclei (AGN) are supermassive black holes with luminous accretion disks found in some galaxies, and are thought to play an important role in galaxy evolution. However, traditional optical spectroscopy for identifying AGN…

Astrophysics of Galaxies · Physics 2022-12-16 Ziting Guo , John F. Wu , Chelsea E. Sharon
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