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We introduce a framework for the enhanced estimation of photometric redshifts using Self-Organising Maps (SOMs). Our method projects galaxy Spectral Energy Distributions (SEDs) onto a two-dimensional map, identifying regions that are…

We present an unsupervised machine learning approach that can be employed for estimating photometric redshifts. The proposed method is based on a vector quantization approach called Self--Organizing Mapping (SOM). A variety of…

Instrumentation and Methods for Astrophysics · Physics 2015-06-03 M. J. Way , C. D. Klose

We present an application of unsupervised machine learning - the self-organised map (SOM) - as a tool for visualising, exploring and mining the catalogues of large astronomical surveys. Self-organisation culminates in a low-resolution…

Instrumentation and Methods for Astrophysics · Physics 2015-05-30 James E. Geach

In this paper we explore the applicability of the unsupervised machine learning technique of Self Organizing Maps (SOM) to estimate galaxy photometric redshift probability density functions (PDFs). This technique takes a spectroscopic…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 M. Carrasco Kind , R. J. Brunner

The upcoming galaxy large-scale surveys, such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST), will generate photometry for billions of galaxies. The interpretation of large-scale weak lensing maps, as well as the…

Instrumentation and Methods for Astrophysics · Physics 2025-10-01 Alvaro Callejas-Tavera , Erik Molino-Minero-Re , Octavio Valenzuela

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

We examine a general framework for visualizing datasets of high (> 2) dimensionality, and demonstrate it using the morphology of galaxies at moderate redshifts. The distributions of various populations of such galaxies are examined in a…

Astrophysics · Physics 2007-05-23 A. Naim , K. U. Ratnatunga , R. E. Griffiths

We propose a new method to estimate the photometric redshift of galaxies by using the full galaxy image in each measured band. This method draws from the latest techniques and advances in machine learning, in particular Deep Neural…

Instrumentation and Methods for Astrophysics · Physics 2016-06-16 Ben Hoyle

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.…

We present photometric redshifts and associated probability distributions for all detected sources in the Extended Chandra Deep Field South (ECDFS). The work makes use of the most up-to-date data from the Cosmic Assembly Near-IR Deep Legacy…

Accurate photometric redshift calibration is central to the robustness of all cosmology constraints from cosmic shear surveys. Analyses of the KiDS re-weighted training samples from all overlapping spectroscopic surveys to provide a direct…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-01 Angus H. Wright , Hendrik Hildebrandt , Jan Luca van den Busch , Catherine Heymans

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

The Euclid survey aims to trace the evolution of cosmic structures up to redshift $z$ $\sim$ 3 and beyond. Its success depends critically on obtaining highly accurate mean redshifts for ensembles of galaxies $n(z)$ in all tomographic bins,…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-18 W. Roster , A. H. Wright , H. Hildebrandt , R. Reischke , O. Ilbert , W. d'Assignies D. , M. Manera , M. Bolzonella , D. C. Masters , S. Paltani , W. G. Hartley , Y. Kang , H. Hoekstra , B. Altieri , A. Amara , S. Andreon , N. Auricchio , C. Baccigalupi , M. Baldi , A. Balestra , S. Bardelli , P. Battaglia , R. Bender , A. Biviano , E. Branchini , M. Brescia , S. Camera , G. Cañas-Herrera , V. Capobianco , C. Carbone , V. F. Cardone , J. Carretero , R. Casas , S. Casas , F. J. Castander , M. Castellano , G. Castignani , S. Cavuoti , K. C. Chambers , A. Cimatti , C. Colodro-Conde , G. Congedo , C. J. Conselice , L. Conversi , Y. Copin , A. Costille , F. Courbin , H. M. Courtois , M. Cropper , A. Da Silva , H. Degaudenzi , S. de la Torre , G. De Lucia , F. Dubath , C. A. J. Duncan , X. Dupac , S. Dusini , S. Escoffier , M. Farina , R. Farinelli , S. Farrens , F. Faustini , S. Ferriol , F. Finelli , P. Fosalba , N. Fourmanoit , M. Frailis , E. Franceschi , M. Fumana , S. Galeotta , K. George , W. Gillard , B. Gillis , C. Giocoli , J. Gracia-Carpio , A. Grazian , F. Grupp , S. V. H. Haugan , W. Holmes , F. Hormuth , A. Hornstrup , P. Hudelot , K. Jahnke , M. Jhabvala , B. Joachimi , E. Keihänen , S. Kermiche , B. Kubik , H. Kurki-Suonio , A. M. C. Le Brun , D. Le Mignant , S. Ligori , P. B. Lilje , V. Lindholm , I. Lloro , D. Maino , E. Maiorano , O. Mansutti , O. Marggraf , M. Martinelli , N. Martinet , F. Marulli , R. J. Massey , E. Medinaceli , S. Mei , M. Melchior , Y. Mellier , M. Meneghetti , E. Merlin , G. Meylan , A. Mora , M. Moresco , L. Moscardini , R. Nakajima , C. Neissner , S. -M. Niemi , C. Padilla , F. Pasian , K. Pedersen , V. Pettorino , S. Pires , G. Polenta , M. Poncet , L. A. Popa , L. Pozzetti , F. Raison , R. Rebolo , A. Renzi , J. Rhodes , G. Riccio , E. Romelli , M. Roncarelli , C. Rosset , E. Rossetti , R. Saglia , Z. Sakr , D. Sapone , B. Sartoris , M. Schirmer , P. Schneider , T. Schrabback , M. Scodeggio , A. Secroun , E. Sefusatti , G. Seidel , S. Serrano , P. Simon , C. Sirignano , G. Sirri , J. Skottfelt , L. Stanco , J. Steinwagner , P. Tallada-Crespí , A. N. Taylor , H. I. Teplitz , I. Tereno , N. Tessore , S. Toft , R. Toledo-Moreo , F. Torradeflot , I. Tutusaus , L. Valenziano , J. Valiviita , T. Vassallo , G. Verdoes Kleijn , A. Veropalumbo , Y. Wang , J. Weller , G. Zamorani , F. M. Zerbi , E. Zucca , C. Burigana , L. Gabarra , C. Porciani , V. Scottez , M. Sereno

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

Given multiband photometric data from the SDSS DR6, we estimate galaxy redshifts. We employ a Random Forest trained on color features and spectroscopic redshifts from 80,000 randomly chosen primary galaxies yielding a mapping from color to…

The Red-Sequence Cluster Survey (RCS) provides a large and deep photometric catalog of galaxies in the $z'$ and $R_c$ bands for ~90 square degrees of sky, and supplemental $V$ and $B$ data have been obtained for 33.6 deg$^{2}$. We compile a…

Astrophysics · Physics 2009-11-10 B. C. Hsieh , H. K. C. Yee , H. Lin , M. D. Gladders

We use extensive multi-wavelength photometric data from the Great Observatories Origins Deep Survey (GOODS) to estimate photometric redshifts for a sample of 434 galaxies with spectroscopic redshifts in the Chandra Deep Field South. Using…

We use the deepest and the most comprehensive photometric data currently available for GOODS-South galaxies to measure their photometric redshifts. The photometry includes VLT/VIMOS (U-band), HST/ACS (F435W, F606W, F775W, and F850LP bands),…

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