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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

With the advancement of technology, machine learning-based analytical methods have pervaded nearly every discipline in modern studies. Particularly, a number of methods have been employed to estimate the redshift of gamma-ray loud active…

High Energy Astrophysical Phenomena · Physics 2023-12-13 Sarvesh Gharat , Abhimanyu Borthakur , Gopal Bhatta

Cosmic metal enrichment is one of the key physical processes regulating galaxy formation and the evolution of the intergalactic medium (IGM). However, determining the metal content of the most distant galaxies has proven so far almost…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-09 A. Pallottini , S. Gallerani , A. Ferrara , B. Yue , L. Vallini , R. Maiolino , C. Feruglio

We use deep Hubble Space Telescope imaging of the Frontier Fields to accurately measure the galaxy rest-frame ultraviolet luminosity function (UV LF) in the redshift range $z \sim 6-8$. We combine observations in three lensing clusters…

We compute the ionizing radiation field at low redshift, arising from Seyferts, QSOs, and starburst galaxies. This calculation combines recent Seyfert luminosity functions, extrapolated ultraviolet fluxes from our IUE-AGN database, and a…

Astrophysics · Physics 2009-10-31 J. M. Shull , D. Roberts , M. L. Giroux , S. V. Penton , M. A. Fardal

We have obtained deep NIR narrow and broad (J and Y) band imaging data of the GOODS-South field. The narrow band filter is centered at 1060 nm corresponding to redshifts $z = 0.62, 1.15, 1.85$ for the strong emission lines H$\alpha$,…

A simple optical to mid-IR color selection, R-[24] > 14, i.e. f_nu(24) / f_nu(R) > 1000, identifies highly dust obscured galaxies (DOGs) with typical redshifts of z~2 +/- 0.5. Extreme mid-IR luminosities (L_{IR} > 10^{12-14}) suggest that…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 J. Melbourne , S. Bussman , K. Brand , V. Desai , L. Armus , Arjun Dey , B. T. Jannuzi , J. R. Houck , K. Matthews , B. T. Soifer

We present different methods used to identify high redshift (z>5) objects in the high-magnification regions of lensing galaxy clusters, taking advantage of very well constrained lensing models. The research procedures are explained and…

Astrophysics · Physics 2017-03-29 J. Richard , R. Pello , J. -P. Kneib , D. Schaerer , M. R. Santos , R. Ellis

The redshifted spectral line radiation emitted from both atomic fine-structure and molecular rotational transitions in the interstellar medium (ISM) of high-redshift galaxies can be detected in the centimetre, millimetre and submillimetre…

Astrophysics · Physics 2009-10-31 Andrew W. Blain , D. T. Frayer , J. J. Bock , N. Z. Scoville

Our aim is to explore the nature of emission line galaxies by combining high-resolution observations obtained in different bands to understand which objects are powered by an Active Galactic Nucleus(AGN). From the spectroscopic Palomar…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 B. Balmaverde , A. Capetti

The star formation rate (SFR) is one of the most fundamental parameters of galaxies, but nearly all of the standard SFR diagnostics are difficult to measure in active galaxies because of contamination from the active galactic nucleus (AGN).…

Astrophysics of Galaxies · Physics 2023-08-21 Ming-Yang Zhuang , Luis C. Ho , Jinyi Shangguan

Low-mass starbursting galaxies have been proposed as the explanation of the excess of faint galaxies observed at intermediate redshifts. If this hypothesis is correct, then intermediate redshift galaxies should rotate more slowly than…

Astrophysics · Physics 2009-10-28 Luc Simard , Christopher J. Pritchet

We present a morphological classification of 14,245 radio active galactic nuclei (AGNs) into six types, i.e., typical Fanaroff--Riley Class I / II (FRI/II), FRI/II-like bent-tailed, X-shaped radio galaxy, and ringlike radio galaxy, by…

Astrophysics of Galaxies · Physics 2019-02-20 Zhixian Ma , Haiguang Xu , Jie Zhu , Dan Hu , Weitian Li , Chenxi Shan , Zhenghao Zhu , Liyi Gu , Jinjin Li , Chengze Liu , Xiangping Wu

The properties of galaxies at redshift $z>6$ hold the key to our understanding of the early stages of galaxy evolution and can potentially identify the sources of the ultraviolet radiation that give rise to the epoch of reionisation. The…

Using a new color-color diagnostic diagram in the mid infrared built from WISE data, the MIRDD, we compare narrow emission-line galaxies (NELGs) that exhibit different activity types (star-forming galaxies, SFGs, and AGNs, i.e.,LINERs, Sy2s…

Astrophysics of Galaxies · Physics 2015-05-27 R. Coziol , J. P. Torres-Papaqui , H. Andernach

We present the results of a VLT and HST imaging survey aimed at the identification of 4.5<z<6 galaxies. In the VLT data, a set of broad and intermediate band filters has been used to select 13 high--$z$ candidates in a Z(AB)<25 catalog,…

Astrophysics · Physics 2009-11-07 A. Fontana , F. Poli , N. Menci , M. Nonino , E. Giallongo , S. Cristiani , S. D'Odorico

We report the detection of H$_2$O maser emission in 4 out of 77 (5.2%) mid-IR red galaxies that meet the color criteria of $W1-W2 > 0.5$ and $W1-W4 > 7$ and are classified as Type-2 AGNs based on optical, near-IR, and mid-IR spectral energy…

Astrophysics of Galaxies · Physics 2024-11-26 C. Y. Kuo , C. Y. Tai , A. Constantin , J. A. Braatz , H. H. Chung , B. Y. Chen , D. W. Pesce , C. M. V. Impellizzeri , F. Gao , Y. Y. Chang

We propose a new method for identifying active galactic nuclei (AGN) in low mass ($\rm M_*\leq10^{10}M_\odot$) galaxies. This method relies on spectral energy distribution (SED) fitting to identify galaxies whose radio flux density has an…

We present the fourth list with results of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS hereafter, SAO - Special Astrophysical Observatory, Russia). The list is a result of the follow-up spectroscopy conducted with the 6m SAO RAS…