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We perform an analysis of photometric redshifts estimated by using a non-representative training sets in magnitude space. We use the ANNz2 and GPz algorithms to estimate the photometric redshift both in simulations as well as in real data…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-12 J. D. Rivera , B. Moraes , A. I. Merson , S. Jouvel , F. B. Abdalla , M. C. B Abdalla

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

Cosmology and galaxy evolution studies with LSST, \Euclid, and {\it Roman}, will require accurate redshifts for the detected galaxies. In this study, we present improved photometric redshift estimates for galaxies using a template library…

Astrophysics of Galaxies · Physics 2020-08-06 Bomee Lee , Ranga-Ram Chary

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

Photometric redshifts (photo-$z$s) are an essential tool for galaxy evolution science with JWST. However, for deep surveys with more limited filter sets (i.e. $N_{\text{filt}} \sim6$) such as large pure parallel surveys, the most commonly…

Astrophysics of Galaxies · Physics 2025-11-07 Kenneth J. Duncan

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…

In the next decade, the LSST will become a major facility for the astronomical community. However accurately determining the redshifts of the observed galaxies without using spectroscopy is a major challenge. Reconstruction of the redshifts…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Alexia Gorecki , Alexandra Abate , Réza Ansari , Aurélien Barrau , Sylvain Baumont , Marc Moniez , Jean-Stéphane Ricol

In this work, we studied the impact of galaxy morphology on photometric redshift (photo-$z$) probability density functions (PDFs). By including galaxy morphological parameters like the radius, axis-ratio, surface brightness and the S\'ersic…

Cosmology and Nongalactic Astrophysics · Physics 2021-07-09 John Y. H. Soo , Benjamin Joachimi

Accurate redshift estimates are a vital component in understanding galaxy evolution and precision cosmology. In this paper, we explore approaches to increase the applicability of machine learning models for photometric redshift estimation…

Instrumentation and Methods for Astrophysics · Physics 2026-01-27 Jonathan Soriano , Tuan Do , Srinath Saikrishnan , Vikram Seenivasan , Bernie Boscoe , Jack Singal , Evan Jones

ANNZ is a fast and simple algorithm which utilises artificial neural networks (ANNs), it was known as one of the pioneers of machine learning approaches to photometric redshift estimation decades ago. We enhanced the algorithm by…

Precision photometric redshifts will be essential for extracting cosmological parameters from the next generation of wide-area imaging surveys. In this paper we introduce a photometric redshift algorithm, ArborZ, based on the…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-06 David W. Gerdes , Adam J. Sypniewski , Timothy A. McKay , Jiangang Hao , Matthew R. Weis , Risa H. Wechsler , Michael T. Busha

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…

Wide-area imaging surveys are one of the key ways of advancing our understanding of cosmology, galaxy formation physics, and the large-scale structure of the Universe in the coming years. These surveys typically require calculating…

Astrophysics of Galaxies · Physics 2020-10-07 P. W. Hatfield , I. A. Almosallam , M. J. Jarvis , N. Adams , R. A. A. Bowler , Z. Gomes , S. J. Roberts , C. Schreiber

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

Using a grid of $\sim 2$ million elements ($\Delta z = 0.005$) adapted from COSMOS photometric redshift (photo-z) searches, we investigate the general properties of template-based photo-z likelihood surfaces. We find these surfaces are…

Astrophysics of Galaxies · Physics 2016-08-03 Joshua S. Speagle , Peter L. Capak , Daniel J. Eisenstein , Daniel C. Masters , Charles L. Steinhardt

In this work, we explore methods to improve galaxy redshift predictions by combining different ground truths. Traditional machine learning models rely on training sets with known spectroscopic redshifts, which are precise but only represent…

Instrumentation and Methods for Astrophysics · Physics 2024-11-28 Jonathan Soriano , Srinath Saikrishnan , Vikram Seenivasan , Bernie Boscoe , Jack Singal , Tuan Do

Photometric redshifts (photo-z's) provide an alternative way to estimate the distances of large samples of galaxies and are therefore crucial to a large variety of cosmological problems. Among the various methods proposed over the years,…

Instrumentation and Methods for Astrophysics · Physics 2017-06-13 Stefano Cavuoti , Massimo Brescia , Valeria Amaro , Civita Vellucci , Giuseppe Longo , Crescenzo Tortora

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…

The accurate estimation of photometric redshifts plays a crucial role in accomplishing science objectives of the large survey projects. The template-fitting and machine learning are the two main types of methods applied currently. Based on…

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