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We provide a new approach to measure power spectra and reconstruct time series in active galactic nuclei (AGNs) based on the fact that the Fourier transform of AGN stochastic variations is a series of complex Gaussian random variables. The…

Instrumentation and Methods for Astrophysics · Physics 2018-03-14 Yan-Rong Li , Jian-Min Wang

Active galactic nuclei (AGN) are a promising source for high-energy astrophysical neutrinos (HEANs). By the end of 2022, the Vera C. Rubin Observatory (VRO) will begin to observe $\gtrsim10$ million AGN with a regular and high cadence.…

High Energy Astrophysical Phenomena · Physics 2022-07-13 Cyril Creque-Sarbinowski , Marc Kamionkowski , Bei Zhou

We present the first direct measurements of the rest-frame 10-40 keV X-ray luminosity function (XLF) of Active Galactic Nuclei (AGNs) based on a sample of 94 sources at 0.1 < z <3, selected at 8-24 keV energies from sources in the NuSTAR…

We explore spectroscopic and photometric methods for identifying high-redshift galaxies containing an Active Galactic Nucleus (AGN) with JWST observations. After demonstrating the limitations of standard optical methods, which appear…

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 nine years of gamma-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves of more than two thousand active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different…

High Energy Astrophysical Phenomena · Physics 2020-07-01 P. Peñil , A. Domínguez , S. Buson , M. Ajello , J. Otero-Santos , J. A. Barrio , R. Nemmen , S. Cutini , B. Rani , A. Franckowiak , E. Cavazzuti

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

We present a comprehensive analysis of the X-ray spectral properties of 198 newly identified active galactic nuclei (AGNs), leveraging archival data from the {\it Chandra} X-ray Observatory. All these AGNs exhibit a powerlaw spectral…

High Energy Astrophysical Phenomena · Physics 2024-10-08 Samrat Ghosh , Samir Mandal , Sudip Bhattacharyya , Shivam Kumaran

Kpc-scale dual and offset Active Galactic Nuclei (AGNs) are signposts of accreting supermassive black holes (SMBHs) triggered during late-stage galaxy mergers, offering crucial insights into the coevolution of SMBHs and galaxies. However,…

Astrophysics of Galaxies · Physics 2024-05-27 Junyao Li , Ming-Yang Zhuang , Yue Shen , Marta Volonteri , Nianyi Chen , Tiziana Di Matteo

With the advent of large-scale astronomical surveys such as the Zwicky Transient Facility (ZTF), the number of alerts generated by transient, variable and moving astronomical objects is growing rapidly, reaching millions per night.…

Earth and Planetary Astrophysics · Physics 2024-01-12 R. Le Montagner , J. Peloton , B. Carry , J. Desmars , D. Hestroffer , R. A. Mendez , A. C. Perlbarg , W. Thuillot

We assemble a sample of 733 dwarf galaxies ($M_{\ast} \le 10^{9.5} \text{M}_\odot$) with signatures of active galactic nuclei (AGN) and explore the intersection between different AGN selection techniques. Objects in our database are…

Astrophysics of Galaxies · Physics 2024-05-31 Erik J. Wasleske , Vivienne F. Baldassare

The emission line luminosity function of active galactic nuclei (AGN) is measured from about 3000 AGN included in the main galaxy sample of the Sloan Digital Sky Survey within a redshift range of $0<z<0.15$. The $\Ha$ and [OIII]$\lambda…

Machine learning has become essential for automated classification of astronomical transients, but current approaches face significant limitations: classifiers trained on simulations struggle with real data, models developed for one survey…

Instrumentation and Methods for Astrophysics · Physics 2025-07-10 Rithwik Gupta , Daniel Muthukrishna , Nabeel Rehemtulla , Ved Shah

In this project we use data obtained by Zwicky Transient Facility to develop and test a neural-network-based, multiband classification algorithm to classify periodic variable stars (i.e. pulsating variable stars and eclipsing binaries). The…

Instrumentation and Methods for Astrophysics · Physics 2026-02-25 Tamás Szklenár , Attila Bódi , Róbert Szabó

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

We design and successfully implement artificial neural networks (ANNs) to detect and classify entanglement for three-qubit systems using limited state features. The overall design principle is a feed forward neural network (FFNN), with the…

Quantum Physics · Physics 2024-11-19 Jorawar Singh , Vaishali Gulati , Kavita Dorai , Arvind

Efficient automated detection of flux-transient, reoccurring flux-variable, and moving objects is increasingly important for large-scale astronomical surveys. We present braai, a convolutional-neural-network, deep-learning real/bogus…

Identifying active galactic nuclei (AGN) and isolating their contribution to a galaxy's energy budget is crucial for studying the co-evolution of AGN and their host galaxies. Brightness temperature ($T_b$) measurements from high-resolution…

We present a measure of the hard (2-8 keV) X-ray luminosity function (XLF) of Active Galactic Nuclei up to z~5. At high redshifts, the wide area coverage of the Chandra Multiwavength Project is crucial to detect rare and luminous (Lx >…

In this paper we give a brief review of the astrophysics of active galactic nuclei (AGN). After a general introduction motivating the study of AGNs, we discuss our present understanding of the inner workings of the central engines, most…

Cosmology and Nongalactic Astrophysics · Physics 2013-01-18 Henric Krawczynski , Ezequiel Treister