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Machine learning techniques offer a precious tool box for use within astronomy to solve problems involving so-called big data. They provide a means to make accurate predictions about a particular system without prior knowledge of the…

Instrumentation and Methods for Astrophysics · Physics 2019-01-01 J. Elliott , R. S. de Souza , A. Krone-Martins , E. Cameron , E. E. O. Ishida , J. Hilbe

We present a method, PhotoWeb, for estimating photometric redshifts of individual galaxies, and their equivalent distance, with megaparsec and even sub-megaparsec accuracy using the Cosmic Web as a constraint over photo-z estimates.…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-30 Miguel A. Aragon-Calvo , Rien van de Weygaert , Bernard J. T. Jones , Bahram Mobasher

We present a catalogue of photometric redshifts for galaxies from DESI Legacy Imaging Surveys, which includes $\sim0.18$ billion sources covering 14,000 ${\rm deg}^2$. The photometric redshifts, along with their uncertainties, are estimated…

Astrophysics of Galaxies · Physics 2025-02-25 Xingchen Zhou , Nan Li , Hu Zou , Yan Gong , Furen Deng , Xuelei Chen , Qian Yu , Zizhao He , Boyi Ding

Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a…

Instrumentation and Methods for Astrophysics · Physics 2016-06-29 J. Elliott , R. S. de Souza , A. Krone-Martins , E. Cameron , E. E. O. Ishida , J. Hilbe

In the modern galaxy surveys photometric redshifts play a central role in a broad range of studies, from gravitational lensing and dark matter distribution to galaxy evolution. Using a dataset of about 25,000 galaxies from the second data…

Instrumentation and Methods for Astrophysics · Physics 2017-06-14 Stefano Cavuoti , Crescenzo Tortora , Massimo Brescia , Giuseppe Longo , Mario Radovich , Nicola R. Napolitano , Valeria Amaro , Civita Vellucci

We present a method to refine photometric redshift galaxy catalogs by comparing their color-space matching with overlapping spectroscopic calibration data. We focus on cases where photometric redshifts (photo-$z$) are estimated empirically.…

The next generation of large scale imaging surveys (such as those conducted with the Large Synoptic Survey Telescope and Euclid) will require accurate photometric redshifts in order to optimally extract cosmological information. Gaussian…

Astrophysics of Galaxies · Physics 2018-01-24 Zahra Gomes , Matt J. Jarvis , Ibrahim A. Almosallam , Stephen J. Roberts

Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will originate at redshifts greater than 5 yet a number of high redshift candidates may be left unconfirmed due to the lack of measured redshifts. Here we introduce…

Based on the SDSS and SDSS-WISE quasar datasets, we put forward two schemes to estimate the photometric redshifts of quasars. Our schemes are based on the idea that the samples are firstly classified into subsamples by a classifier and then…

Instrumentation and Methods for Astrophysics · Physics 2019-12-05 Yanxia Zhang , Jingyi Zhang , Xin Jin , Yongheng Zhao

Accurate photometric redshifts are among the key requirements for precision weak lensing measurements. Both the large size of the Sloan Digital Sky Survey (SDSS) and the existence of large spectroscopic redshift samples that are…

Based on the Sloan Digital Sky Survey Data Release 5 Galaxy Sample, we explore photometric morphology classification and redshift estimation of galaxies using photometric data and known spectroscopic redshifts. An unsupervised method,…

Astrophysics · Physics 2009-11-13 Yanxia Zhang , Lili Li , Yongheng Zhao

This study explores the use of symbolic regression (SR) combined with genetic algorithms (GA) to classify astronomical objects. Using the SDSS17 dataset from Kaggle, which includes 100,000 observations of stars, galaxies, and quasars, we…

Astrophysics of Galaxies · Physics 2025-03-14 Fabio R. Llorella , José A. Cebrián

(abridged)Photometric redshifts for AGN (galaxies hosting an accreting supermassive black hole in their center) are notoriously challenging and currently better computed via SED fitting, assuming that deep photometry for many wavelengths is…

We apply machine learning in the form of a nearest neighbor instance-based algorithm (NN) to generate full photometric redshift probability density functions (PDFs) for objects in the Fifth Data Release of the Sloan Digital Sky Survey (SDSS…

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

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

Photometric redshifts are estimated on the basis of template scenarios with the help of the code ZPEG, an extension of the galaxy evolution model PEGASE.2 and available on the PEGASE web site. The spectral energy distribution (SED)…

Astrophysics · Physics 2009-11-07 Damien Le Borgne , Brigitte Rocca-Volmerange

Accurate estimation of photometric redshifts (photo-$z$) is crucial in studies of both galaxy evolution and cosmology using current and future large sky surveys. In this study, we employ Random Forest (RF), a machine learning algorithm, to…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-27 Junhao Lu , Zhijian Luo , Zhu Chen , Liping Fu , Wei Du , Yan Gong , Yicheng Li , Xian-Min Meng , Zhirui Tang , Shaohua Zhang , Chenggang Shu , Xingchen Zhou , Zuhui Fan

We present a new scheme, $\it{galtag}$, for refining the photometric redshift measurements of faint galaxies by probabilistically tagging them to observed galaxy groups constructed from a brighter, magnitude-limited spectroscopy survey.…

Astrophysics of Galaxies · Physics 2018-07-04 P. R. Kafle , A. S. G. Robotham , S. P. Driver , S. Deeley , P. Norberg , M. J. Drinkwater , L. J. Davies

We present the methodology and data behind the photometric redshift database of the Sloan Digital Sky Survey Data Release 12 (SDSS DR12). We adopt a hybrid technique, empirically estimating the redshift via local regression on a…

Astrophysics of Galaxies · Physics 2016-06-21 Róbert Beck , László Dobos , Tamás Budavári , Alexander S. Szalay , István Csabai