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We use a contrastive self-supervised learning framework to estimate distances to galaxies from their photometric images. We incorporate data augmentations from computer vision as well as an application-specific augmentation accounting for…

Instrumentation and Methods for Astrophysics · Physics 2021-01-13 Md Abul Hayat , Peter Harrington , George Stein , Zarija Lukić , Mustafa Mustafa

Galaxy clusters identified with optical imaging tend to suffer from projection effects, which impact richness (the number of member galaxies in a cluster) and lensing coherently. Physically unassociated galaxies can be mistaken as cluster…

Reducing the scatter between cluster mass and optical richness is a key goal for cluster cosmology from photometric catalogs. We consider various modifications to the red-sequence matched filter richness estimator of Rozo et al. (2009), and…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 E. S. Rykoff , B. P. Koester , E. Rozo , J. Annis , A. E. Evrard , S. M. Hansen , J. Hao , D. E. Johnston , T. A. McKay , R. H. Wechsler

Weak-lensing measurements of the averaged shear profiles of galaxy clusters binned by some proxy for cluster mass are commonly converted to cluster mass estimates under the assumption that these cluster stacks have spherical symmetry. In…

We introduce AutoEnRichness, a hybrid approach that combines empirical and analytical strategies to determine the richness of galaxy clusters (in the redshift range of $0.1 \leq z \leq 0.35$) using photometry data from the Sloan Digital Sky…

Cosmology and Nongalactic Astrophysics · Physics 2022-08-26 Matthew C. Chan , John P. Stott

Sky surveys are the largest data generators in astronomy, making automated tools for extracting meaningful scientific information an absolute necessity. We show that, without the need for labels, self-supervised learning recovers…

Instrumentation and Methods for Astrophysics · Physics 2022-06-30 Md Abul Hayat , George Stein , Peter Harrington , Zarija Lukić , Mustafa Mustafa

This review summarizes popular unsupervised learning methods, and gives an overview of their past, current, and future uses in astronomy. Unsupervised learning aims to organise the information content of a dataset, in such a way that…

Instrumentation and Methods for Astrophysics · Physics 2024-06-26 Sotiria Fotopoulou

Identifying galaxy clusters through overdensities of galaxies in photometric surveys is the oldest and arguably the most economic and mass-sensitive detection method, compared to X-ray and Sunyaev-Zel'dovich Effect surveys that detect the…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-01 J. E. Geach , J. A. Peacock

We present a modified adaptive matched filter algorithm designed to identify clusters of galaxies in wide-field imaging surveys such as the Sloan Digital Sky Survey. The cluster-finding technique is fully adaptive to imaging surveys with…

Astrophysics · Physics 2009-11-13 Feng Dong , Elena Pierpaoli , James E. Gunn , Risa H. Wechsler

Classifying stars, galaxies, and quasars is essential for understanding cosmic structure and evolution; however, the vast data from modern surveys make manual classification impractical, while supervised learning methods remain constrained…

Astrophysics of Galaxies · Physics 2025-09-09 Vahid Asadi , Hosein Haghi , Akram Hasani Zonoozi

We present the use of self-supervised learning to explore and exploit large unlabeled datasets. Focusing on 42 million galaxy images from the latest data release of the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys, we…

Instrumentation and Methods for Astrophysics · Physics 2021-12-02 George Stein , Peter Harrington , Jacqueline Blaum , Tomislav Medan , Zarija Lukic

Robust galaxy cluster mass estimates are fundamental for constraining cosmological parameters from counts. For this reason, it is essential to search for tracers that, independent of the cluster's dynamical state, have a small intrinsic…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-19 Lia Doubrawa , Eduardo S. Cypriano , Alexis Finoguenov , Paulo A. A. Lopes , Matteo Maturi , Anthony H. Gonzalez , Renato Dupke

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

In Astronomy, a huge amount of image data is generated daily by photometric surveys, which scan the sky to collect data from stars, galaxies and other celestial objects. In this paper, we propose a technique to leverage unlabeled…

Computer Vision and Pattern Recognition · Computer Science 2020-06-26 Ana Martinazzo , Mateus Espadoto , Nina S. T. Hirata

We examine the relationship between the total X-ray and optical luminosities of groups and clusters of galaxies taken from various samples in the literature. The clusters and groups were drawn from four different catalogs: (1) the Abell/ACO…

Astrophysics · Physics 2007-05-23 Christopher J. Miller , Adrian L. Melott , Robert C. Nichol

Assessing the blurriness of an object image is fundamentally important to improve the performance for object recognition and retrieval. The main challenge lies in the lack of abundant images with reliable labels and effective learning…

Computer Vision and Pattern Recognition · Computer Science 2022-07-14 Qiang Li , Zhaoliang Yao , Jingjing Wang , Ye Tian , Pengju Yang , Di Xie , Shiliang Pu

In the era of huge astronomical surveys, machine learning offers promising solutions for the efficient estimation of galaxy properties. The traditional, `supervised' paradigm for the application of machine learning involves training a model…

Astrophysics of Galaxies · Physics 2022-12-21 A. Humphrey , P. A. C. Cunha , A. Paulino-Afonso , S. Amarantidis , R. Carvajal , J. M. Gomes , I. Matute , P. Papaderos

The clustering signals of galaxy clusters are known to be powerful tools for self-calibrating the mass-observable relation and are complementary to cluster abundance and lensing. In this work, we explore the possibility of combining three…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-04 Chenxiao Zeng , Andrés N. Salcedo , Hao-Yi Wu , Christopher M. Hirata

The cluster correlation function and its richness dependence are determined from 1108 clusters of galaxies -- the largest sample of clusters studied so far -- found in 379 deg^2 of Sloan Digital Sky Survey early data. The results are…

Astrophysics · Physics 2009-11-10 Neta A. Bahcall , Feng Dong , Lei Hao , Paul Bode , Jim Annis , James E. Gunn , Donald P. Schneider

We measure the two-point spatial correlation function for clusters selected from the photometric MaxBCG galaxy cluster catalog for the Sloan Digital Sky Survey (SDSS). We evaluate the correlation function for several cluster samples using…

Astrophysics · Physics 2014-11-18 Juan Estrada , Emiliano Sefusatti , Joshua A. Frieman
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