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Most of the variability studies of active galactic nuclei (AGNs) are based on ensemble analyses. Nevertheless, it is interesting to provide estimates of the individual variability properties of each AGN, in order to relate them with…

Astrophysics of Galaxies · Physics 2020-11-17 M. Laurenti , F. Vagnetti , R. Middei , M. Paolillo

Modern sky surveys produce vast amounts of observational data, making the application of classical methods for estimating galaxy properties challenging and time-consuming. This challenge can be significantly alleviated by employing…

Astrophysics of Galaxies · Physics 2025-09-17 Olena Torbaniuk , Lars Doorenbos , Maurizio Paolillo , Stefano Cavuoti , Massimo Brescia , Giuseppe Longo

We fit the near-infrared to radio spectral energy distributions of a sample of 30 luminous and ultra-luminous infrared galaxies with models that include both starburst and AGN components. The aim of the work was to determine important…

Astrophysics of Galaxies · Physics 2009-02-10 O. Vega , M. S. Clemens , A. Bressan , G. L. Granato , L. Silva , P. Panuzzo

We studied the physical parameters of a sample comprising of all Spitzer/IRS public spectra of Seyfert galaxies in the mid-infrared (5.2-38$\mu$m range) under the active galactic nuclei (AGN) unified model. We compare the observed spectra…

Astrophysics of Galaxies · Physics 2016-09-29 Anelise Audibert , Rogério Riffel , Dinalva A. Sales , Miriani G. Pastoriza , Daniel Ruschel-Dutra

A X-ray background synthesis model is used to calculate the contribution of Active Galactic Nuclei (AGNs) to the 1.4 GHz number counts between 100 nJy and 10 mJy. The number counts are broken down into contributions from radio-quiet and…

Cosmology and Nongalactic Astrophysics · Physics 2011-02-11 D. R. Ballantyne

To enhance the efficiency, scalability, and cross-survey applicability of stellar parameter inference in large spectroscopic datasets, we present a modular, parallelized Python framework with automated error estimation, built on the LAMOST…

We present medium resolution (R approx. 1500) ISO-SWS 2.4--45 micron spectra of a sample of 29 galaxies with active nuclei. This data set is rich in fine structure emission lines tracing the narrow line regions and (circum-)nuclear star…

Astrophysics · Physics 2009-11-07 E. Sturm , D. Lutz , A. Verma , H. Netzer , A. Sternberg , A. F. M. Moorwood , E. Oliva , R. Genzel

We present a new method to estimate the average star formation rate per unit stellar mass (SSFR) of a stacked population of galaxies. We combine the spectra of 600-1000 galaxies with similar stellar masses and parameterise the star…

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 have conducted a study to quantify the systematic differences resulting from using different stellar population models in optical spectroscopic identification of type II AGN. We examined the different AGN detection fractions of 7069…

Astrophysics of Galaxies · Physics 2018-07-18 Yan-Ping Chen , Ingyin Zaw , Glennys R Farrar

(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…

Active galactic nuclei (AGNs) are the compact, energetic central regions of galaxies, powered by supermassive black holes that accrete surrounding gas and dust. Their optical spectra can be identified by strong emission-line signatures…

Astrophysics of Galaxies · Physics 2026-01-09 Sruthi Suresh , Wei Jeat Hon , Rachel L Webster , Christian Wolf , Christopher A Onken

We use mid-infrared spectroscopy of unobscured active galactic nuclei (AGNs) to reveal their native dusty environments. We concentrate on Seyfert 1 galaxies, observing a sample of 31 with the Infrared Spectrograph aboard the Spitzer Space…

Astrophysics of Galaxies · Physics 2010-01-15 G. D. Thompson , N. A. Levenson , S. A. Uddin , M. M. Sirocky

We present a 5-8 micron analysis of the Spitzer-IRS spectra of 71 ultraluminous infrared galaxies (ULIRGs) with redshift z < 0.15, devoted to the study of the role of active galactic nuclei (AGN) and starbursts (SB) as the power source of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 E. Nardini , G. Risaliti , M. Salvati , E. Sani , Y. Watabe , A. Marconi , R. Maiolino

We use bulge-type classifications of 809 representative SDSS galaxies by Gadotti (2009) to classify a large sample of galaxies into real bulges (classical or elliptical) and pseudobulges using Random Forest. We use structural and stellar…

Astrophysics of Galaxies · Physics 2020-02-05 Hassen M. Yesuf , S. M. Faber , David C. Koo , Joanna Woo , Joel R. Primack , Yifei Luo

We investigate the differences in the stellar population properties, the structure, and the environment between massive compact star-forming galaxies (cSFGs) with or without active galactic nucleus (AGN) at $2<z<3$ in the five…

Astrophysics of Galaxies · Physics 2022-08-10 Shiying Lu , Yizhou Gu , Guanwen Fang , Qirong Yuan , Min Bao , Xiaotong Guo

The nature of the UV-Optical continuum in Seyfert 2 galaxies is a matter of current debate, fundamental to which is the issue of characterizing and quantifying the stellar population contribution to the nuclear spectra. Using high S/N…

Astrophysics · Physics 2007-05-23 Thaisa Storchi-Bergmann , H. R. Schmitt , R. Cid Fernandes

The complexity of constraining the stellar initial mass function (IMF) in early-type galaxies cannot be overstated, given the necessity of both very high signal-to-noise (S/N) data and the difficulty of breaking the strong degeneracies that…

Astrophysics of Galaxies · Physics 2021-10-27 Ilaria Lonoce , Anja Feldmeier-Krause , Wendy L. Freedman

Using new APEX and JCMT spectroscopy of the CO 2-1 line, we undertake a controlled study of cold molecular gas in moderately luminous Active Galactic Nuclei (AGN) and inactive galaxies from the Luminous Local AGN with Matched Analogs…

I review the relationship between star formation and black hole building, based on spectroscopic observations of the stellar population in active galactic nuclei (AGNs) and their host galaxies. My emphasis is on large, well-defined local…

Astrophysics · Physics 2007-05-23 Timothy M. Heckman