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The cosmological redshift of a galaxy's light is inferable from its observable properties in images. Because imaging is much easier to acquire than spectroscopic observations that would allow the identification of distinct line features,…

Instrumentation and Methods for Astrophysics · Physics 2026-05-11 Luca Tortorelli , Daniel Grün

We used 3.1 million spectroscopically labelled sources from the Sloan Digital Sky Survey (SDSS) to train an optimised random forest classifier using photometry from the SDSS and the Widefield Infrared Survey Explorer (WISE). We applied this…

Astrophysics of Galaxies · Physics 2020-07-15 A. O. Clarke , A. M. M. Scaife , R. Greenhalgh , V. Griguta

We present METAPHOR (Machine-learning Estimation Tool for Accurate PHOtometric Redshifts), a method able to provide a reliable PDF for photometric galaxy redshifts estimated through empirical techniques. METAPHOR is a modular workflow,…

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

We present a star/galaxy classification for the Southern Photometric Local Universe Survey (S-PLUS), based on a Machine Learning approach: the Random Forest algorithm. We train the algorithm using the S-PLUS optical photometry up to $r$=21,…

We present a list of quasar candidates including photometric redshift estimates from the miniJPAS Data Release constructed using SQUEzE. This work is based on machine-learning classification of photometric data of quasar candidates using…

We introduce Z-Sequence, a novel empirical model that utilises photometric measurements of observed galaxies within a specified search radius to estimate the photometric redshift of galaxy clusters. Z-Sequence itself is composed of a…

Astrophysics of Galaxies · Physics 2021-04-26 Matthew C. Chan , John P. Stott

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…

Identifying stars belonging to different classes is vital in order to build up statistical samples of different phases and pathways of stellar evolution. In the era of surveys covering billions of stars, an automated method of identifying…

Instrumentation and Methods for Astrophysics · Physics 2024-10-31 Sean Enis Cody , Sebastian Scher , Iain McDonald , Albert Zijlstra , Emma Alexander , Nick L. J. Cox

We present zephyr, a novel method that integrates cutting-edge normalizing flow techniques into a mixture density estimation framework, enabling the effective use of heterogeneous training data for photometric redshift inference. Compared…

Instrumentation and Methods for Astrophysics · Physics 2023-11-01 Zechang Sun , Joshua S. Speagle , Song Huang , Yuan-Sen Ting , Zheng Cai

The WISE satellite has detected hundreds of millions sources over the entire sky. Classifying them reliably is however a challenging task due to degeneracies in WISE multicolour space and low levels of detection in its two…

Astrophysics of Galaxies · Physics 2016-07-13 Agnieszka Kurcz , Maciej Bilicki , Aleksandra Solarz , Magdalena Krupa , Agnieszka Pollo , Katarzyna Małek

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

We apply four statistical learning methods to a sample of $7941$ galaxies ($z<0.06$) from the Galaxy and Mass Assembly (GAMA) survey to test the feasibility of using automated algorithms to classify galaxies. Using $10$ features measured…

Machine-learning based classifiers have become indispensable in the field of astrophysics, allowing separation of astronomical sources into various classes, with computational efficiency suitable for application to the enormous data volumes…

Instrumentation and Methods for Astrophysics · Physics 2022-10-26 A. Humphrey , W. Kuberski , J. Bialek , N. Perrakis , W. Cools , N. Nuyttens , H. Elakhrass , P. A. C. Cunha

The availability of large, public, multi-modal astronomical datasets presents an opportunity to execute novel research that straddles the line between science of AI and science of astronomy. Photometric redshift estimation is a…

Instrumentation and Methods for Astrophysics · Physics 2024-02-07 Andrew Engel , Gautham Narayan , Nell Byler

We present a new method for inferring photometric redshifts in deep galaxy and quasar surveys, based on a data driven model of latent spectral energy distributions (SEDs) and a physical model of photometric fluxes as a function of redshift.…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-29 Boris Leistedt , David W. Hogg

Classification will be an important first step for upcoming surveys that will detect billions of new sources such as LSST and Euclid, as well as DESI, 4MOST and MOONS. The application of traditional methods of model fitting and…

Astrophysics of Galaxies · Physics 2020-01-29 Crispin Logan , Sotiria Fotopoulou

We present a Bayesian hierarchical framework to analyze photometric galaxy survey data with stellar population synthesis (SPS) models. Our method couples robust modeling of spectral energy distributions with a population model and a noise…

Instrumentation and Methods for Astrophysics · Physics 2023-01-18 Boris Leistedt , Justin Alsing , Hiranya Peiris , Daniel Mortlock , Joel Leja

We present a new non-parametric method to quantify morphologies of galaxies based on a particular family of learning machines called support vector machines. The method, that can be seen as a generalization of the classical CAS…

Astrophysics · Physics 2009-11-13 M. Huertas-Company , D. Rouan , L. Tasca , G. Soucail , O. Le Fevre

Photometric redshift estimation is an indispensable tool of precision cosmology. One problem that plagues the use of this tool in the era of large-scale sky surveys is that the bright galaxies that are selected for spectroscopic observation…

Instrumentation and Methods for Astrophysics · Physics 2017-07-18 Peter E. Freeman , Rafael Izbicki , Ann B. Lee

We introduce a new method to determine galaxy cluster membership based solely on photometric properties. We adopt a machine learning approach to recover a cluster membership probability from galaxy photometric parameters and finally derive…

Cosmology and Nongalactic Astrophysics · Physics 2020-02-26 P. A. A. Lopes , A. L. B. Ribeiro