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We apply a combination of a Genetic Algorithms (GA) and Support Vector Machines (SVM) machine learning algorithm to solve two important problems faced by the astronomical community: star/galaxy separation, and photometric redshift…

Instrumentation and Methods for Astrophysics · Physics 2016-04-27 S. Heinis , S. Kumar , S. Gezari , W. S. Burgett , K. C. Chambers , P. W. Draper , H. Flewelling , N. Kaiser , E. A. Magnier , N. Metcalfe , C. Waters

Most existing star-galaxy classifiers use the reduced summary information from catalogs, requiring careful feature extraction and selection. The latest advances in machine learning that use deep convolutional neural networks allow a machine…

Instrumentation and Methods for Astrophysics · Physics 2016-10-20 Edward J. Kim , Robert J. Brunner

We use the Random Forest (RF) algorithm to develop a tool for automated activity classification of galaxies into 5 different classes: Star-forming (SF), AGN, LINER, Composite, and Passive. We train the algorithm on a combination of mid-IR…

Astrophysics of Galaxies · Physics 2023-03-22 Elias Kyritsis , Charalampos Daoutis , Andreas Zezas , Konstantinos Kouroumpatzakis

Owing to recent advances in radial-velocity instrumentation and observation techniques, the detection of Earth-mass planets around Sun-like stars may soon be primarily limited by intrinsic stellar variability. Several processes contribute…

Solar and Stellar Astrophysics · Physics 2021-12-22 Michael L. Palumbo , Eric B. Ford , Jason T. Wright , Suvrath Mahadevan , Alexander W. Wise , Johannes Löhner-Böttcher

Model fitting is frequently used to determine the shape of galaxies and the point spread function, for examples, in weak lensing analyses or morphology studies aiming at probing the evolution of galaxies. However, the number of parameters…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-03 Guoliang Li , Bo Xin , Wei Cui

Modern astronomical surveys are producing datasets of unprecedented size and richness, increasing the potential for high-impact scientific discovery. This possibility, coupled with the challenge of exploring a large number of sources, has…

Instrumentation and Methods for Astrophysics · Physics 2024-04-01 Verlon Etsebeth , Michelle Lochner , Mike Walmsley , Margherita Grespan

Statistics of the weak lensing of galaxies can be used to constrain cosmology if the galaxy shear can be estimated accurately. In general this requires accurate modelling of unlensed galaxy shapes and the point spread function (PSF). I…

Astrophysics of Galaxies · Physics 2009-09-07 Antony Lewis

Photometric surveys produce large-area maps of the galaxy distribution, but with less accurate redshift information than is obtained from spectroscopic methods. Modern photometric redshift (photo-z) algorithms use galaxy magnitudes, or…

Cosmology and Nongalactic Astrophysics · Physics 2016-06-15 J. Asorey , M. Carrasco Kind , I. Sevilla-Noarbe , R. J. Brunner , J. Thaler

Here, we present a machine vision approach, combining a VAE framework with PCA, to decipher galaxy images. Using mock gri-band images from the EAGLE simulation, the VAE finds that around 35 features are needed to describe the images. Adding…

Astrophysics of Galaxies · Physics 2025-11-27 Samuel Howie , Ting-Yun Cheng , Carlton M. Baugh

Classification of stars and galaxies is a well-known astronomical problem that has been treated using different approaches, most of them relying on morphological information. In this paper, we tackle this issue using the low-resolution…

Clusters of galaxies are important laboratories for understanding both galaxy evolution and constraining cosmological quantities. Any analysis of clusters, however, is best done when one can reliably determine which galaxies are members of…

Astrophysics · Physics 2009-10-31 R. J. Brunner , L. M. Lubin

We construct a galaxy groups catalogue from the public 100K data release of the 2dF galaxy redshift survey. The group identification is carried out using a slightly modified version of the group finding algorithm developed by Huchra &…

Astrophysics · Physics 2009-11-07 Manuel Merchan , Ariel Zandivarez

Gravitational lensing has become one of the most powerful tools available for investigating the 'dark side' of the universe. Cosmological strong gravitational lensing, in particular, probes the properties of the dense cores of dark matter…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-30 Nan Li , Michael D. Gladders , Esteban M. Rangel , Michael K. Florian , Lindsey E. Bleem , Katrin Heitmann , Salman Habib , Patricia Fasel

We train deep learning models on thousands of galaxy catalogues from the state-of-the-art hydrodynamic simulations of the CAMELS project to perform regression and inference. We employ Graph Neural Networks (GNNs), architectures designed to…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-10 Pablo Villanueva-Domingo , Francisco Villaescusa-Navarro

Intrinsic galaxy alignments are a source of bias for weak lensing measurements as well as a tool for understanding galaxy formation and evolution. In this work, we measure the alignment of shapes of satellite galaxies, in galaxy groups,…

We present a novel approach for classifying star-forming galaxies using photometric images. By utilizing approximately $124,000$ optical color composite images and spectroscopic data of nearby galaxies at $0.01<z<0.06$ from the Sloan…

Astrophysics of Galaxies · Physics 2025-08-01 Kyuseok Oh , M. Dennis Turp

The statistical properties of the ellipticities of galaxy images depend on how galaxies form and evolve, and therefore constrain models of galaxy morphology, which are key to the removal of the intrinsic alignment contamination of…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-28 B. Joachimi , E. Semboloni , P. E. Bett , J. Hartlap , S. Hilbert , H. Hoekstra , P. Schneider , T. Schrabback

We present an extended morphometric system to automatically classify galaxies from astronomical images. The new system includes the original and modified versions of the CASGM coefficients (Concentration $C_1$, Asymmetry $A_3$, and…

Astrophysics of Galaxies · Physics 2015-09-21 Fabricio Ferrari , Reinaldo Ramos de Carvalho , Marina Trevisan

The detection of astrophysical Gamma-Ray Bursts (GRBs) has always been intertwined with the challenge of identifying the direction of the source. Accurate angular localization of better than a degree has been achieved to date only with…

Instrumentation and Methods for Astrophysics · Physics 2021-02-25 Roi Rahin , Luca Moleri , Alex Vdovin , Amir Feigenboim , Solomon Margolin , Shlomit Tarem , Ehud Behar , Max Ghelman , Alon Osovizky

We constrain the distributions of projected radial alignment angles of satellite galaxy shapes within the Galaxy And Mass Assembly survey group catalogue. We identify the galaxy groups using spectroscopic redshifts and measure galaxy…

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