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We introduce ANNz, a freely available software package for photometric redshift estimation using Artificial Neural Networks. ANNz learns the relation between photometry and redshift from an appropriate training set of galaxies for which the…

Astrophysics · Physics 2009-08-21 Adrian A. Collister , Ofer Lahav

A new approach to estimating photometric redshifts - using Artificial Neural Networks (ANNs) - is investigated. Unlike the standard template-fitting photometric redshift technique, a large spectroscopically-identified training set is…

Astrophysics · Physics 2009-11-07 Andrew E. Firth , Ofer Lahav , Rachel S. Somerville

This study aims to improve the photometric redshifts (photo-$z$s) of galaxies by integrating two contemporary methods: template-fitting and machine learning. Finding the synergy between these two methods was not a high priority in the past,…

Cosmology and Nongalactic Astrophysics · Physics 2023-11-30 Ishaq Y. K. Alshuaili , John Y. H. Soo , Mohd Zubir Mat Jafri , Yasmin Rafid

We present ANNz2, a new implementation of the public software for photometric redshift (photo-z) estimation of Collister and Lahav (2004), which now includes generation of full probability distribution functions (PDFs). ANNz2 utilizes…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-24 Iftach Sadeh , Filipe B. Abdalla , Ofer Lahav

We calculate photometric redshifts from the Sloan Digital Sky Survey Data Release 2 Galaxy Sample using artificial neural networks (ANNs). Different input patterns based on various parameters (e.g. magnitude, color index, flux information)…

Astrophysics · Physics 2007-05-23 Lili Li , Yanxia Zhang , Yongheng Zhao , Dawei Yang

Computing photo-z for AGN is challenging, primarily due to the interplay of relative emissions associated with the SMBH and its host galaxy. SED fitting methods, effective in pencil-beam surveys, face limitations in all-sky surveys with…

The redshifts of galaxies are a key attribute that is needed for nearly all extragalactic studies. Since spectroscopic redshifts require additional telescope and human resources, millions of galaxies are known without spectroscopic…

Astrophysics of Galaxies · Physics 2021-07-21 S. Schuldt , S. H. Suyu , R. Cañameras , S. Taubenberger , T. Meinhardt , L. Leal-Taixé , B. C. Hsieh

Accurate photometric redshifts are a lynchpin for many future experiments to pin down the cosmological model and for studies of galaxy evolution. In this study, a novel sparse regression framework for photometric redshift estimation is…

Instrumentation and Methods for Astrophysics · Physics 2025-06-03 Ibrahim A. Almosallam , Sam N. Lindsay , Matt J. Jarvis , Stephen J. Roberts

We present photometric redshifts for 1 341 559 galaxies from the Physics of the Accelerating Universe Survey (PAUS) over 50.38 ${\rm deg}^{2}$ of sky to $i_{\rm AB}=23$. Redshift estimation is performed using DEEPz, a deep-learning…

Current and future imaging surveys require photometric redshifts (photo-zs) to be estimated for millions of galaxies. Improving the photo-z quality is a major challenge but is needed to advance our understanding of cosmology. In this paper…

Instrumentation and Methods for Astrophysics · Physics 2023-03-22 L. Cabayol , M. Eriksen , J. Carretero , R. Casas , F. J. Castander , E. Fernández , J. Garcia-Bellido , E. Gaztanaga , H. Hildebrandt , H. Hoekstra , B. Joachimi , R. Miquel , C. Padilla , A. Pocino , E. Sanchez , S. Serrano , I. Sevilla , M. Siudek , P. Tallada-Crespí , N. Aghanim , A. Amara , N. Auricchio , M. Baldi , R. Bender , D. Bonino , E. Branchini , M. Brescia , J. Brinchmann , S. Camera , V. Capobianco , C. Carbone , M. Castellano , S. Cavuoti , A. Cimatti , R. Cledassou , G. Congedo , C. J. Conselice , L. Conversi , Y. Copin , L. Corcione , F. Courbin , M. Cropper , A. Da Silva , H. Degaudenzi , M. Douspis , F. Dubath , C. A. J. Duncan , X. Dupac , S. Dusini , S. Farrens , P. Fosalba , M. Frailis , E. Franceschi , P. Franzetti , B. Garilli , W. Gillard , B. Gillis , C. Giocoli , A. Grazian , F. Grupp , S. V. H. Haugan , W. Holmes , F. Hormuth , A. Hornstrup , P. Hudelot , K. Jahnke , M. Kümme , S. Kermiche , A. Kiessling , M. Kilbinger , R. Kohley , H. Kurki-Suonio , S. Ligori , P. B. Lilje , I. Lloro , E. Maiorano , O. Mansutti , O. Marggraf , K. Markovic , F. Marulli , R. Massey , M. Meneghetti , E. Merlin , G. Meylan , M. Moresco , L. Moscardini , E. Munari , R. Nakajima , S. M. Niemi , S. Paltani , F. Pasian , K. Pedersen , V. Pettorino , G. Polenta , M. Poncet , L. Popa , L. Pozzetti , F. Raison , R. Rebolo , J. Rhodes , G. Riccio , C. Rosset , E. Rossetti , R. Saglia , B. Sartoris , P. Schneider , A. Secroun , G. Seide , C. Sirignano , G. Sirri , L. Stanco , A. N. Taylor , I. Tereno , R. Toledo-Moreo , F. Torradeflot , I. Tutusaus , E. Valentijn , L. Valenziano , Y. Wang , J. Weller , G. Zamorani , J. Zoubian , S. Andreon , S. Mei , V. Scottez , A. Tramacere

Knowing the redshift of galaxies is one of the first requirements of many cosmological experiments, and as it's impossible to perform spectroscopy for every galaxy being observed, photometric redshift (photo-z) estimations are still of…

Instrumentation and Methods for Astrophysics · Physics 2022-03-09 Ben Henghes , Connor Pettitt , Jeyan Thiyagalingam , Tony Hey , Ofer Lahav

In order to answer the open questions of modern cosmology and galaxy evolution theory, robust algorithms for calculating photometric redshifts (photo-z) for very large samples of galaxies are needed. Correct estimation of the various…

Instrumentation and Methods for Astrophysics · Physics 2021-08-25 Oleksandra Razim , Stefano Cavuoti , Massimo Brescia , Giuseppe Riccio , Mara Salvato , Giuseppe Longo

Accurate estimation of photometric redshifts (photo-$z$s) is crucial for cosmological surveys. Various methods have been developed for this purpose, such as template fitting methods and machine learning techniques, each with its own…

Broadband photometry offers a time and cost effective method to reconstruct the continuum emission of celestial objects. Thus, photometric redshift estimation has supported the scientific exploitation of extragalactic multiwavelength…

Astrophysics of Galaxies · Physics 2018-10-31 S. Fotopoulou , S. Paltani

Accurate photometric redshift (photo-$z$) estimation is a key challenge in cosmology, as uncertainties in photo-$z$ directly limit the scientific return of large-scale structure and weak lensing studies, especially in upcoming Stage IV…

Instrumentation and Methods for Astrophysics · Physics 2025-12-10 Yiming Ren , Kwan Chuen Chan , Le Zhang , Yin Li , Haolin Zhang , Ruiyu Song , Yan Gong , Xian-Min Meng , Xingchen Zhou

We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. We use the Artificial Neural Network (ANN) technique to calculate photo-z's and the Nearest Neighbor Error…

With the launch of eROSITA (extended Roentgen Survey with an Imaging Telescope Array), successfully occurred on 2019 July 13, we are facing the challenge of computing reliable photometric redshifts for 3 million of active galactic nuclei…

Instrumentation and Methods for Astrophysics · Physics 2019-09-04 M. Brescia , M. Salvato , S. Cavuoti , T. T. Ananna , G. Riccio , S. M. LaMassa , C. M. Urry , G. Longo

We present a machine-learning photometric redshift analysis of the Kilo-Degree Survey Data Release 3, using two neural-network based techniques: ANNz2 and MLPQNA. Despite limited coverage of spectroscopic training sets, these ML codes…

We present photometric redshifts (photo-$z$) for the deep wide fields of the Physics of the Accelerating Universe Survey (PAUS), covering an area of $\sim$50 deg$^{2}$, for $\sim$1.8 million objects up to $i_{\textrm{AB}}<23$. The PAUS deep…

Building on the first paper in this series (Duncan et al. 2018), we present a study investigating the performance of Gaussian process photometric redshift (photo-z) estimates for galaxies and active galactic nuclei detected in deep radio…

Astrophysics of Galaxies · Physics 2018-05-24 Kenneth J Duncan , Matt J. Jarvis , Michael J. I. Brown , Huub J. A. Rottgering
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