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Precision photometric redshifts will be essential for extracting cosmological parameters from the next generation of wide-area imaging surveys. In this paper we introduce a photometric redshift algorithm, ArborZ, based on the…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-06 David W. Gerdes , Adam J. Sypniewski , Timothy A. McKay , Jiangang Hao , Matthew R. Weis , Risa H. Wechsler , Michael T. Busha

Many scientific investigations of photometric galaxy surveys require redshift estimates, whose uncertainty properties are best encapsulated by photometric redshift (photo-z) posterior probability density functions (PDFs). A plethora of…

The estimation and utilization of photometric redshift probability density functions (photo-$z$ PDFs) has become increasingly important over the last few years and currently there exist a wide variety of algorithms to compute photo-$z$'s,…

Cosmology and Nongalactic Astrophysics · Physics 2014-06-05 M. Carrasco Kind , R. J. Brunner

The need to analyze the available large synoptic multi-band surveys drives the development of new data-analysis methods. Photometric redshift estimation is one field of application where such new methods improved the results, substantially.…

Instrumentation and Methods for Astrophysics · Physics 2018-01-31 Antonio D'Isanto , Kai Lars Polsterer

A variety of fundamental astrophysical science topics require the determination of very accurate photometric redshifts (photo-z's). A wide plethora of methods have been developed, based either on template models fitting or on empirical…

Instrumentation and Methods for Astrophysics · Physics 2016-12-13 Stefano Cavuoti , Valeria Amaro , Massimo Brescia , Civita Vellucci , Crescenzo Tortora , Giuseppe Longo

We present ANNz2, a new implementation of the public software for photometric redshift (photo-z) estimation of Collister and Lahav (2004), which now includes generation of full probability distribution functions (PDFs). ANNz2 utilizes…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-24 Iftach Sadeh , Filipe B. Abdalla , Ofer Lahav

Accurate estimation of photometric redshifts (photo-$z$) is crucial in studies of both galaxy evolution and cosmology using current and future large sky surveys. In this study, we employ Random Forest (RF), a machine learning algorithm, to…

Cosmology and Nongalactic Astrophysics · Physics 2023-12-27 Junhao Lu , Zhijian Luo , Zhu Chen , Liping Fu , Wei Du , Yan Gong , Yicheng Li , Xian-Min Meng , Zhirui Tang , Shaohua Zhang , Chenggang Shu , Xingchen Zhou , Zuhui Fan

The need for accurate photometric redshifts estimation is a topic that has fundamental importance in Astronomy, due to the necessity of efficiently obtaining redshift information without the need of spectroscopic analysis. We propose a…

Instrumentation and Methods for Astrophysics · Physics 2017-06-14 Antonio D'Isanto

Despite the high accuracy of photometric redshifts (zphot) derived using Machine Learning (ML) methods, the quantification of errors through reliable and accurate Probability Density Functions (PDFs) is still an open problem. First, because…

The accurate estimation of photometric redshifts is crucial to many upcoming galaxy surveys, for example the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). Almost all Rubin extragalactic and cosmological science requires…

Instrumentation and Methods for Astrophysics · Physics 2022-05-04 Natalia Stylianou , Alex I. Malz , Peter Hatfield , John Franklin Crenshaw , Julia Gschwend

In this paper we explore the applicability of the unsupervised machine learning technique of Self Organizing Maps (SOM) to estimate galaxy photometric redshift probability density functions (PDFs). This technique takes a spectroscopic…

Instrumentation and Methods for Astrophysics · Physics 2015-06-18 M. Carrasco Kind , R. J. Brunner

Photometric redshifts (photo-z's) provide an alternative way to estimate the distances of large samples of galaxies and are therefore crucial to a large variety of cosmological problems. Among the various methods proposed over the years,…

Instrumentation and Methods for Astrophysics · Physics 2017-06-13 Stefano Cavuoti , Massimo Brescia , Valeria Amaro , Civita Vellucci , Giuseppe Longo , Crescenzo Tortora

Photometric redshifts play an important role as a measure of distance for various cosmological topics. Spectroscopic redshifts are only available for a very limited number of objects but can be used for creating statistical models. A broad…

Instrumentation and Methods for Astrophysics · Physics 2016-08-30 Kai Lars Polsterer , Antonio D'Isanto , Fabian Gieseke

Photometric wide-field surveys are imaging the sky in unprecedented detail. These surveys face a significant challenge in efficiently estimating galactic photometric redshifts while accurately quantifying associated uncertainties. In this…

The amount, size, and complexity of astronomical data-sets and databases are growing rapidly in the last decades, due to new technologies and dedicated survey telescopes. Besides dealing with poly-structured and complex data, sparse data…

Instrumentation and Methods for Astrophysics · Physics 2021-03-08 Kai Lars Polsterer , Antonio D'Isanto , Sebastian Lerch

A trustworthy estimate of the redshift distribution $n(z)$ is crucial for using weak gravitational lensing and large-scale structure of galaxy catalogs to study cosmology. Spectroscopic redshifts for the dim and numerous galaxies of…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-27 Alex I. Malz , David W. Hogg

Obtaining accurate photometric redshift estimations is an important aspect of cosmology, remaining a prerequisite of many analyses. In creating novel methods to produce redshift estimations, there has been a shift towards using machine…

Instrumentation and Methods for Astrophysics · Physics 2021-07-07 Ben Henghes , Connor Pettitt , Jeyan Thiyagalingam , Tony Hey , Ofer Lahav

We present a neural network classification (NNC) method for photometric redshift estimation that produces well-calibrated redshift probability density functions (PDFs). The method discretizes the redshift space into ordered bins and…

Astrophysics of Galaxies · Physics 2026-05-08 Da-Chuan Tian , Zhong-Lue Wen , Jun-Qing Xia

Accurate estimation of photometric redshifts (photo-$z$s) is crucial for cosmological surveys. Various methods have been developed for this purpose, such as template fitting methods and machine learning techniques, each with its own…

The next generation of cosmology experiments will be required to use photometric redshifts rather than spectroscopic redshifts. Obtaining accurate and well-characterized photometric redshift distributions is therefore critical for Euclid,…

Instrumentation and Methods for Astrophysics · Physics 2025-06-03 Ibrahim A. Almosallam , Matt J. Jarvis , Stephen J. Roberts
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