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We present a new approach to obtaining photometric redshifts using a kernel learning technique called Support Vector Machines (SVMs). Unlike traditional spectral energy distribution fitting, this technique requires a large and…

Astrophysics · Physics 2009-11-10 Yogesh Wadadekar

We conduct a detailed analysis of the photometric redshift requirements for the proposed Dark Energy Survey (DES) using two sets of mock galaxy simulations and an artificial neural network code - ANNz. In particular, we examine how optical…

Astrophysics · Physics 2010-03-26 Manda Banerji , Filipe B. Abdalla , Ofer Lahav , Huan Lin

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

Large direct-imaging surveys usually use a template-fitting technique to estimate photometric redshifts for galaxies, which are then applied to derive important galaxy properties such as luminosities and stellar masses. These estimates can…

Astrophysics of Galaxies · Physics 2015-06-22 B. C. Hsieh , H. K. C. Yee

The accuracy of galaxy photometric redshift (photo-$z$) can significantly affect the analysis of weak gravitational lensing measurements, especially for future high-precision surveys. In this work, we try to extract photo-$z$ information…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-11 Xingchen Zhou , Yan Gong , Xian-Min Meng , Ye Cao , Xuelei Chen , Zhu Chen , Wei Du , Liping Fu , Zhijian Luo

Spectroscopic datasets are essential for training and calibrating photometric redshift (photo-$z$) methods. However, spectroscopic redshifts (spec-$z$'s) constitute a biased and sparse sampling of the photometric galaxy population, which…

The next generation of cosmology experiments will be required to use photometric redshifts rather than spectroscopic redshifts. Obtaining accurate and well-characterized photometric redshift distributions is therefore critical for Euclid,…

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

Context. Strong lensing mass measurements require the knowledge of the redshift of both the lens and the source galaxy. Traditionally, spectroscopic redshifts are used for this purpose. Upcoming surveys, however, will lead to the discovery…

Astrophysics of Galaxies · Physics 2022-04-15 Alessandro Sonnenfeld

We present a forward modeling framework for estimating galaxy redshift distributions from photometric surveys. Our forward model is composed of: a detailed population model describing the intrinsic distribution of physical characteristics…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-01 Justin Alsing , Hiranya Peiris , Daniel Mortlock , Joel Leja , Boris Leistedt

For more that seventy years, the measurements of fluxes of galaxies at different wavelengths and derived colours have been used to estimate their corresponding cosmological distances. From the fields of galaxy and AGN evolution to precision…

Astrophysics of Galaxies · Physics 2018-06-06 Mara Salvato , Olivier Ilbert , Ben Hoyle

Powerful current and future cosmological constraints using high precision measurements of the large-scale structure of galaxies and its weak gravitational lensing effects rely on accurate characterization of the redshift distributions of…

Cosmology and Nongalactic Astrophysics · Physics 2018-12-05 Carles Sánchez , Gary M. Bernstein

We present a dataset built for machine learning applications consisting of galaxy photometry, images, spectroscopic redshifts, and structural properties. This dataset comprises 286,401 galaxy images and photometry from the Hyper-Suprime-Cam…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-02 Tuan Do , Bernie Boscoe , Evan Jones , Yun Qi Li , Kevin Alfaro

The forthcoming Wide Area Vista Extragalactic Survey (WAVES) on the 4-metre Multi-Object Spectroscopic Telescope (4MOST) has a key science goal of probing the halo mass function to lower limits than possible with previous surveys. For that…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-03 Gursharanjit Kaur , Maciej Bilicki , Wojciech Hellwing , the WAVES team

Photometric redshifts are a key tool to extract as much information as possible from planned cosmic shear experiments. In this work we aim to test the performances that can be achieved with observations in the near-infrared from space and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Fabio Bellagamba , Massimo Meneghetti , Lauro Moscardini , Micol Bolzonella

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

We use machine learning to identify in color images of high-redshift galaxies an astrophysical phenomenon predicted by cosmological simulations. This phenomenon, called the blue nugget (BN) phase, is the compact star-forming phase in the…

Establishing accurate morphological measurements of galaxies in a reasonable amount of time for future big-data surveys such as EUCLID, the Large Synoptic Survey Telescope or the Wide Field Infrared Survey Telescope is a challenge. Because…

Instrumentation and Methods for Astrophysics · Physics 2017-06-14 D. Tuccillo , M. Huertas-Company , E. Decenciere , S. Velasco-Forero

We apply instance-based machine learning in the form of a k-nearest neighbor algorithm to the task of estimating photometric redshifts for 55,746 objects spectroscopically classified as quasars in the Fifth Data Release of the Sloan Digital…

Forthcoming astronomical surveys are expected to detect new sources in such large numbers that measuring their spectroscopic redshift measurements will be not be practical. Thus, there is much interest in using machine learning to yield the…

Cosmology and Nongalactic Astrophysics · Physics 2022-03-14 S. J. Curran