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Related papers: Classifying galaxy spectra at 0.5<z<1 with self-or…

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Analyses of stellar spectra often begin with the determination of a number of parameters that define a model atmosphere. This work presents a prototype for an automated spectral classification system that uses a 15 nm-wide region around…

Astrophysics · Physics 2016-08-30 C. Allende Prieto

We present an atlas of 129 spectral energy distributions for nearby galaxies, with wavelength coverage spanning from the UV to the mid-infrared. Our atlas spans a broad range of galaxy types, including ellipticals, spirals, merging…

We investigate the formation of clusters of galaxies in an expanding universe using a new code that regrids at a region of high density. In particular we investigate two models for the initial conditions, both with the standard CDM power…

Astrophysics · Physics 2015-06-24 Suvendra N. Dutta

We apply a novel spectral graph technique, that of locally-biased semi-supervised eigenvectors, to study the diversity of galaxies. This technique permits us to characterize empirically the natural variations in observed spectra data, and…

Instrumentation and Methods for Astrophysics · Physics 2016-12-14 David Lawlor , Tamás Budavári , Michael W. Mahoney

This is the first paper in a series devoted to review the main properties of galaxies designated S0 in the Hubble classification system. Our aim is to gather abundant and, above all, robust information on the most relevant physical…

Astrophysics of Galaxies · Physics 2020-06-23 J. L. Tous , J. M. Solanes , J. D. Perea

In this paper we define an observationally robust, multi-parameter space for the classification of nearby and distant galaxies. The parameters include luminosity, color, and the image-structure parameters: size, image concentration,…

Astrophysics · Physics 2009-10-31 Matthew A. Bershady , Anna Jangren , Christopher J. Conselice

With current and upcoming experiments such as WFIRST, Euclid and LSST, we can observe up to billions of galaxies. While such surveys cannot obtain spectra for all observed galaxies, they produce galaxy magnitudes in color filters. This data…

Astrophysics of Galaxies · Physics 2022-10-19 Melanie Simet , Nima Chartab , Yu Lu , Bahram Mobasher

Graphs have become increasingly popular in modeling structures and interactions in a wide variety of problems during the last decade. Graph-based clustering and semi-supervised classification techniques have shown impressive performance.…

Machine Learning · Computer Science 2020-09-01 Zhao Kang , Chong Peng , Qiang Cheng , Xinwang Liu , Xi Peng , Zenglin Xu , Ling Tian

Over the next few years new spectroscopic surveys (from the optical surveys of the Sloan Digital Sky Survey and the 2 degree Field survey through to space-based ultraviolet satellites such as GALEX) will provide the opportunity and…

Astrophysics · Physics 2009-10-31 A. J. Connolly , A. S. Szalay

The immense amount of time series data produced by astronomical surveys has called for the use of machine learning algorithms to discover and classify several million celestial sources. In the case of variable stars, supervised learning…

Solar and Stellar Astrophysics · Physics 2022-10-12 R. Pantoja , M. Catelan , K. Pichara , P. Protopapas

This work identifies the orientation of galaxies in the Galaxy zoo data set. The images are first identified by the number of principal components required to represent 99 percent of the variance of the image. K means clustering is used to…

Astrophysics of Galaxies · Physics 2020-10-27 Vijay Shankar A

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 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 work, we select the high signal-to-noise ratio spectra of stars from the LAMOST data andmap theirMK classes to the spectral features. The equivalentwidths of the prominent spectral lines, playing the similar role as the multi-color…

Solar and Stellar Astrophysics · Physics 2015-05-25 Chao Liu , Wen-Yuan Cui , Bo Zhang , Jun-Chen Wan , Li-Cai Deng , Yonghui Hou , Yuefei Wang , Ming Yang , Yong Zhang

The available magnetic field data from the terrestrial magnetosphere, solar wind and planetary magnetospheres exceeds over $10^6$ hours. Identifying plasma waves in these large data sets is a time consuming and tedious process. In this…

Space Physics · Physics 2021-10-04 Daniel Vech , David M. Malaspina

The Coma supercluster (100 Mpc) offers an unprecedented contiguous range of environments in the nearby Universe. In this paper we present a catalogue of spectroscopically confirmed galaxies in the Coma supercluster detected in the…

Astrophysics of Galaxies · Physics 2018-06-06 Smriti Mahajan , Ankit Singh , Devika Shobhana

There has been an increasing interest in semi-supervised learning in the recent years because of the great number of datasets with a large number of unlabeled data but only a few labeled samples. Semi-supervised learning algorithms can work…

Machine Learning · Computer Science 2020-03-26 Pedro H. M. Braga , Hansenclever F. Bassani

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

While we already seem to have a general scenario of the evolution of different types of galaxies, a complete and satisfactory understanding of the processes that led to the formation of all the variety of today's galaxy types is still…

Astrophysics of Galaxies · Physics 2022-11-23 M. Siudek , K. Lisiecki , M. Mezcua , K. Małek , A. Pollo , J. Krywult , A. Karska , Junais

The current and upcoming large data volume galaxy surveys require the use of machine learning techniques to maximize their scientific return. This study explores the use of Self-Organizing Maps (SOMs) to estimate galaxy parameters with a…