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Galaxy groups are essential for studying the distribution of matter on a large scale in redshift surveys and for deciphering the link between galaxy traits and their associated halos. In this work, we propose a widely applicable method for…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-03 Juntao Ma , Jie Wang , Tianxiang Mao , Hongxiang Chen , Yuxi Meng , Xiaohu Yang , Qingyang Li

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

Photometric redshifts are essential in studies of both galaxy evolution and cosmology, as they enable analyses of objects too numerous or faint for spectroscopy. The Rubin Observatory, Euclid, and Roman Space Telescope will soon provide a…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-28 Jeffrey A. Newman , Daniel Gruen

MLPQNA stands for Multi Layer Perceptron with Quasi Newton Algorithm and it is a machine learning method which can be used to cope with regression and classification problems on complex and massive data sets. In this paper we give the…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 M. Brescia , S. Cavuoti , R. D'Abrusco , G. Longo , A. Mercurio

Photometric redshift estimation is becoming an increasingly important technique, although the currently existing methods present several shortcomings which hinder their application. Here it is shown that most of those drawbacks are…

Astrophysics · Physics 2011-05-05 Narciso Benitez

Much of the science that is made possible by multiwavelength redshift surveys requires the use of photometric redshifts. But as these surveys become more ambitious, and as we seek to perform increasingly accurate measurements, it becomes…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-23 Ryan F. Quadri , Rik J. Williams

Large imaging surveys will rely on photometric redshifts (photo-z's), which are typically estimated through machine learning methods. Currently planned spectroscopic surveys will not be deep enough to produce a representative training…

The importance of photometric galaxy redshift estimation is rapidly increasing with the development of specialised powerful observational facilities. We develop a new photometric redshift estimation workflow TOPz to provide reliable and…

Many astrophysical analyses depend on estimates of redshifts (a proxy for distance) determined from photometric (i.e., imaging) data alone. Inaccurate estimates of photometric redshift uncertainties can result in large systematic errors.…

Instrumentation and Methods for Astrophysics · Physics 2022-05-31 Biprateep Dey , Jeffrey A. Newman , Brett H. Andrews , Rafael Izbicki , Ann B. Lee , David Zhao , Markus Michael Rau , Alex I. Malz

Three-dimensional wide-field galaxy surveys are fundamental for cosmological studies. For higher redshifts (z > 1.0), where galaxies are too faint, quasars still trace the large-scale structure of the Universe. Since available telescope…

Instrumentation and Methods for Astrophysics · Physics 2022-09-21 Sándor Kunsági-Máté , Róbert Beck , István Szapudi , István Csabai

Weak lensing surveys are reaching sensitivities at which uncertainties in the galaxy redshift distributions n(z) from photo-z errors degrade cosmological constraints. We use ray-tracing simulations and a simple treatment of photo-z errors…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-24 Matthew W. Abruzzo , Zoltán Haiman

We estimated photometric redshifts (zphot) for more than 1.1 million galaxies of the ESO Public Kilo-Degree Survey (KiDS) Data Release 2. KiDS is an optical wide-field imaging survey carried out with the VLT Survey Telescope (VST) and the…

Aims. We explore machine learning techniques to forecast star formation rate, stellar mass, and metallicity across galaxies with redshifts ranging from 0.01 to 0.3. Methods. Leveraging CatBoost and deep learning architectures, we utilize…

Astrophysics of Galaxies · Physics 2024-05-27 F. Z. Zeraatgari , F. Hafezianzadeh , Y. -X. Zhang , A. Mosallanezhad , J. -Y. Zhang

Accurate photometric redshifts are among the key requirements for precision weak lensing measurements. Both the large size of the Sloan Digital Sky Survey (SDSS) and the existence of large spectroscopic redshift samples that are…

Aims: We present a custom support vector machine classification package for photometric redshift estimation, including comparisons with other methods. We also explore the efficacy of including galaxy shape information in redshift…

Instrumentation and Methods for Astrophysics · Physics 2017-04-12 Evan Jones , J. Singal

We introduce redMaGiC, an automated algorithm for selecting Luminous Red Galaxies (LRGs). The algorithm was specifically developed to minimize photometric redshift uncertainties in photometric large-scale structure studies. redMaGiC…

Given multiband photometric data from the SDSS DR6, we estimate galaxy redshifts. We employ a Random Forest trained on color features and spectroscopic redshifts from 80,000 randomly chosen primary galaxies yielding a mapping from color to…

We introduce a new effective strategy to assign group and cluster membership probabilities $P_{mem}$ to galaxies using photometric redshift information. Large dynamical ranges both in halo mass and cosmic time are considered. The method…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-09 Gianluca Castignani , Christophe Benoist

We present a new approach to the problem of estimating the redshift of galaxies from photometric data. The approach uses a genetic algorithm combined with non-linear regression to model the 2SLAQ LRG data set with SDSS DR7 photometry. The…

Instrumentation and Methods for Astrophysics · Physics 2015-04-14 Robert Hogan , Malcolm Fairbairn , Navin Seeburn

We present the result of two binary classifier ensembled neural networks to identify catastrophic outliers for photo-z estimates within the COSMOS field utilizing only 8 and 5 photometric band passes, respectively. Our neural networks can…

Astrophysics of Galaxies · Physics 2025-03-31 Mitchell T. Dennis , Esther M. Hu , Lennox L. Cowie