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Galaxy populations show bimodality in a variety of properties: stellar mass, colour, specific star-formation rate, size, and S\'ersic index. These parameters are our feature space. We use an existing sample of 7556 galaxies from the Galaxy…

We use multi-band optical and near-infrared photometric observations of galaxies in the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) to predict photometric redshifts using artificial neural networks. The…

Astrophysics of Galaxies · Physics 2020-01-15 Derek Wilson , Hooshang Nayyeri , Asantha Cooray , Boris Häußler

Galaxy morphology is a fundamental quantity, that is essential not only for the full spectrum of galaxy-evolution studies, but also for a plethora of science in observational cosmology. While a rich literature exists on…

Astrophysics of Galaxies · Physics 2020-01-08 Garreth Martin , Sugata Kaviraj , Alex Hocking , Shaun C. Read , James E. Geach

The morphology of a galaxy has been shown to encode the evolutionary history and correlates strongly with physical properties such as stellar mass, star formation rates and past merger events. While the majority of galaxies in the local…

Astrophysics of Galaxies · Physics 2023-02-23 Clár-Bríd Tohill , Steven Bamford , Christopher Conselice

Morphological classification conveys abundant information on the formation, evolution, and environment of galaxies. In this work, we refine the two-step galaxy morphological classification framework ({\tt\string USmorph}), which employs a…

Astrophysics of Galaxies · Physics 2024-04-25 Jie Song , GuanWen Fang , Shuo Ba , Zesen Lin , Yizhou Gu , Chichun Zhou , Tao Wang , Cai-Na Hao , Guilin Liu , Hongxin Zhang , Yao Yao , Xu Kong

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

By applying our previously developed two-step scheme for galaxy morphology classification, we present a catalog of galaxy morphology for H-band selected massive galaxies in the COSMOS-DASH field, which includes 17292 galaxies with stellar…

Astrophysics of Galaxies · Physics 2023-07-07 Yao Dai , Jun Xu , Jie Song , Guanwen Fang , Chichun Zhou , Shuo Ba , Yizhou Gu , Zesen Lin , Xu Kong

Morphological classification is a key piece of information to define samples of galaxies aiming to study the large-scale structure of the universe. In essence, the challenge is to build up a robust methodology to perform a reliable…

Instrumentation and Methods for Astrophysics · Physics 2019-11-05 P. H. Barchi , R. R. de Carvalho , R. R. Rosa , R. Sautter , M. Soares-Santos , B. A. D. Marques , E. Clua , T. S. Gonçalves , C. de Sá-Freitas , T. C. Moura

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

Structural properties posses valuable information about the formation and evolution of galaxies, and are important for understanding the past, present, and future universe. Here we use unsupervised machine learning methodology to analyze a…

Instrumentation and Methods for Astrophysics · Physics 2015-05-26 Andrew Schutter , Lior Shamir

We present an unsupervised machine learning technique that automatically segments and labels galaxies in astronomical imaging surveys using only pixel data. Distinct from previous unsupervised machine learning approaches used in astronomy…

Instrumentation and Methods for Astrophysics · Physics 2017-11-08 Alex Hocking , James E. Geach , Yi Sun , Neil Davey

We use automated surface photometry and pattern classification techniques to morphologically classify galaxies. The two-dimensional light distribution of a galaxy is reconstructed using Fourier series fits to azimuthal profiles computed in…

Astrophysics · Physics 2009-11-07 S. C. Odewahn , S. H. Cohen , R. A. Windhorst , N. S. Philip

Although coherent large-scale structures such as filaments and walls are apparent to the eye in galaxy redshift surveys, they have so far proven difficult to characterize with computer algorithms. This paper presents a procedure that uses…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Nicholas Bond , Michael Strauss , Renyue Cen

We describe the application of the `shapelet' linear decomposition of galaxy images to multi-wavelength morphological classification using the $u,g,r,i,$ and $z$-band images of 1519 galaxies from the Sloan Digital Sky Survey. We utilize…

Astrophysics · Physics 2009-11-10 B. C. Kelly , T. A. McKay

We develop a straightforward and quantitative two-step method for spectroscopically classifying galaxies from the low signal-to-noise (S/N) optical spectra typical of galaxy redshift surveys. First, using \chi^2-fitting of characteristic…

Astrophysics · Physics 2009-10-28 Dennis Zaritsky , Ann I. Zabludoff , Jeffrey A. Willick

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

We describe application of the `shapelet' linear decomposition of galaxy images to morphological classification using images of $\sim$ 3000 galaxies from the Sloan Digital Sky Survey. After decomposing the galaxies we perform a principal…

Astrophysics · Physics 2009-11-10 Brandon C. Kelly , Timothy A. McKay

The morphological classification of galaxies is considered a relevant issue and can be approached from different points of view. The increasing growth in the size and accuracy of astronomical data sets brings with it the need for the use of…

Astrophysics of Galaxies · Physics 2023-03-01 M. S. Rosito , L. A. Bignone , P. B. Tissera , S. E. Pedrosa

We explore unsupervised machine learning for galaxy morphology analyses using a combination of feature extraction with a vector-quantised variational autoencoder (VQ-VAE) and hierarchical clustering (HC). We propose a new methodology that…

Quantitative morphological classification of galaxies is important for understanding the origin of type frequency and correlations with environment. But galaxy morphological classification is still mainly done visually by dedicated…

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