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We determine the accuracy of galaxy redshift distributions as estimated from photometric redshift probability distributions $p(z)$. Our method utilises measurements of the angular cross-correlation between photometric galaxies and an…

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

In addition to the maximum likelihood approach, there are two other methods which are commonly used to reconstruct the true redshift distribution from photometric redshift datasets: one uses a deconvolution method, and the other a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Ravi K. Sheth , Graziano Rossi

The development of fast and accurate methods of photometric redshift estimation is a vital step towards being able to fully utilize the data of next-generation surveys within precision cosmology. In this paper we apply a specific approach…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 P. E. Freeman , J. A. Newman , A. B. Lee , J. W. Richards , C. M. Schafer

Measurements of galaxy clustering are now becoming possible over a range of redshifts out to z=3. We use a semi-analytic model of galaxy formation to compute the expected evolution of the galaxy correlation function with redshift. We…

Astrophysics · Physics 2009-10-31 C. M. Baugh , A. J. Benson , S. Cole , C. S. Frenk , C. G. Lacey

Image clustering is a very useful technique that is widely applied to various areas, including remote sensing. Recently, visual representations by self-supervised learning have greatly improved the performance of image clustering. To…

Computer Vision and Pattern Recognition · Computer Science 2022-09-27 Qinglin Li , Guoping Qiu

We discuss an algorithm whereby the massive galaxy clusters detected in the SRG/eROSITA all-sky survey are identified and their photometric redshifts are estimated. For this purpose, we use photometric redshift estimates for galaxies and…

As deeper observations discover increasingly distant galaxies, characterizing the properties of high-redshift galaxy populations will become increasingly challenging and paramount. We present a method for measuring the clustering bias of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Brant E. Robertson

We propose the DPSM method, a density-based node clustering approach that automatically determines the number of clusters and can be applied in both data space and graph space. Unlike traditional density-based clustering methods, which…

Machine Learning · Computer Science 2024-11-05 Feiping Nie , Yitao Song , Jingjing Xue , Rong Wang , Xuelong Li

We discuss the theoretical interpretation of observational data concerning the clustering of galaxies at high redshifts. Building on the theoretical machinery developed by Matarrese et al. (1997), we make detailed quantitative predictions…

Astrophysics · Physics 2009-10-30 Lauro Moscardini , Peter Coles , Francesco Lucchin , Sabino Matarrese

We show how the cosmological constant can be estimated from redshift surveys at different redshifts, using maximum-likelihood techniques. The apparent redshift-space clustering on large scales (\simgt 20 \himpc) are affected in the radial…

Astrophysics · Physics 2009-11-06 Takahiko Matsubara , Alexander S. Szalay

We present a new method for measuring the projected mass distributions of galaxy clusters. The gravitational amplification is measured by comparing the joint distribution in redshift and magnitude of galaxies behind the cluster with that of…

Astrophysics · Physics 2009-10-22 T. J. Broadhurst , A. N. Taylor , J. A. Peacock

Context: In astronomy, new approaches to process and analyze the exponentially increasing amount of data are inevitable. While classical approaches (e.g. template fitting) are fine for objects of well-known classes, alternative techniques…

Astrophysics of Galaxies · Physics 2016-08-08 S. D. Kügler , K. Polsterer , M. Hoecker

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

Clustering is an effective tool for astronomical spectral analysis, to mine clustering patterns among data. With the implementation of large sky surveys, many clustering methods have been applied to tackle spectroscopic and photometric data…

Instrumentation and Methods for Astrophysics · Physics 2022-12-19 Haifeng Yang , Chenhui Shi , Jianghui Cai , Lichan Zhou , Yuqing Yang , Xujun Zhao , Yanting He , Jing Hao

We describe a new method for measuring the true redshift distribution of any set of objects studied only photometrically. The angular cross-correlation between objects in a photometric sample with objects in some spectroscopic sample as a…

Astrophysics · Physics 2009-11-13 Jeffrey A. Newman

Redshift-space clustering anisotropies caused by cosmic peculiar velocities provide a powerful probe to test the gravity theory on large scales. However, to extract unbiased physical constraints, the clustering pattern has to be modelled…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-28 Federico Marulli , Alfonso Veropalumbo , Lauro Moscardini , Andrea Cimatti , Klaus Dolag

Three methods for detecting and characterizing structure in point data, such as that generated by redshift surveys, are described: classification using self-organizing maps, segmentation using Bayesian blocks, and density estimation using…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 M. J. Way , P. R. Gazis , Jeffrey D. Scargle

We present The-wiZZ, an open source and user-friendly software for estimating the redshift distributions of photometric galaxies with unknown redshifts by spatially cross-correlating them against a reference sample with known redshifts. The…

Cosmology and Nongalactic Astrophysics · Physics 2017-02-10 Christopher B. Morrison , Hendrik Hildebrandt , Samuel J. Schmidt , Ivan K. Baldry , Maciej Bilicki , Ami Choi , Thomas Erben , Peter Schneider