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Photometric redshifts (photo-$z$s) are an essential tool for galaxy evolution science with JWST. However, for deep surveys with more limited filter sets (i.e. $N_{\text{filt}} \sim6$) such as large pure parallel surveys, the most commonly…

Astrophysics of Galaxies · Physics 2025-11-07 Kenneth J. Duncan

For more that seventy years, the measurements of fluxes of galaxies at different wavelengths and derived colours have been used to estimate their corresponding cosmological distances. From the fields of galaxy and AGN evolution to precision…

Astrophysics of Galaxies · Physics 2018-06-06 Mara Salvato , Olivier Ilbert , Ben Hoyle

The observational limitations of astronomical surveys lead to significant statistical inference challenges. One such challenge is the estimation of luminosity functions given redshift $z$ and absolute magnitude $M$ measurements from an…

Astrophysics · Physics 2011-02-11 Chad M. Schafer

Accurate photometric redshift (photo-$z$) estimation requires support from multi-band observational data. However, in the actual process of astronomical observations and data processing, some sources may have missing observational data in…

Instrumentation and Methods for Astrophysics · Physics 2024-06-05 Zhijian Luo , Zhirui Tang , Zhu Chen , Liping Fu , Wei Du , Shaohua Zhang , Yan Gong , Chenggang Shu , Junhao Lu , Yicheng Li , Xian-Min Meng , Xingchen Zhou , Zuhui Fan

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

Modern time-domain surveys continuously monitor large swaths of the sky to look for astronomical variability. Astrophysical discovery in such data sets is complicated by the fact that detections of real transient and variable sources are…

Instrumentation and Methods for Astrophysics · Physics 2015-06-11 Henrik Brink , Joseph W. Richards , Dovi Poznanski , Joshua S. Bloom , John Rice , Sahand Negahban , Martin Wainwright

Quasars can be used to measure baryon acoustic oscillations at high redshift, which are considered as direct tracers of the most distant large-scale structures in the Universe. It is fundamental to select quasars from observations before…

Cosmology and Nongalactic Astrophysics · Physics 2022-09-14 Zizhao He , Nan Li

We present a physically inspired model for the problem of redshift estimation. Typically, redshift estimation has been treated as a regression problem that takes as input magnitudes and maps them to a single target redshift. In this work we…

Instrumentation and Methods for Astrophysics · Physics 2016-06-21 Sven D. Kugler , Nikolaos Gianniotis , Kai L. Polsterer

We aim to select quasar candidates based on the two large survey databases, Pan-STARRS and AllWISE. Exploring the distribution of quasars and stars in the color spaces, we find that the combination of infrared and optical photometry is more…

Instrumentation and Methods for Astrophysics · Physics 2019-03-20 Xin Jin , Yanxia Zhang , Jingyi Zhang , Yongheng Zhao , Xue-bing Wu , Dongwei Fan

The automatic classification of X-ray detections is a necessary step in extracting astrophysical information from compiled catalogs of astrophysical sources. Classification is useful for the study of individual objects, statistics for…

Instrumentation and Methods for Astrophysics · Physics 2024-01-30 Víctor Samuel Pérez-Díaz , Juan Rafael Martínez-Galarza , Alexander Caicedo , Raffaele D'Abrusco

We present a classification-based approach to identify quasi-stellar radio sources (quasars) in the Sloan Digital Sky Survey and evaluate its performance on a manually labeled training set. While reasonable results can already be obtained…

Instrumentation and Methods for Astrophysics · Physics 2016-11-18 Fabian Gieseke , Kai Lars Polsterer , Andreas Thom , Peter-Christian Zinn , Dominik Bomanns , Ralf-Jürgen Dettmar , Oliver Kramer , Jan Vahrenhold

In modern astrophysics, the machine learning has increasingly gained more popularity with its incredibly powerful ability to make predictions or calculated suggestions for large amounts of data. We describe an application of the supervised…

Astrophysics of Galaxies · Physics 2018-12-26 Yu Bai , JiFeng Liu , Song Wang , Fan Yang

We present a convolutional neural network to classify distinct cosmological scenarios based on the statistically similar weak-lensing maps they generate. Modified gravity (MG) models that include massive neutrinos can mimic the standard…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-17 Austin Peel , Florian Lalande , Jean-Luc Starck , Valeria Pettorino , Julian Merten , Carlo Giocoli , Massimo Meneghetti , Marco Baldi

We present a method of selecting quasars up to redshift $\approx$ 6 with random forests, a supervised machine learning method, applied to Pan-STARRS1 and WISE data. We find that, thanks to the increasing set of known quasars we can assemble…

The technique of estimating redshifts using photometric rather than spectroscopic observations has recently received great attention due to its simplicity and the accuracy of the results obtained. In this work, we estimate photometric…

Astrophysics · Physics 2007-05-23 S. Kitsionas , E. Hatziminaoglou , I. Georgantopoulos , A. Georgakakis , O. Giannakis

Based on the SDSS and SDSS-WISE quasar datasets, we put forward two schemes to estimate the photometric redshifts of quasars. Our schemes are based on the idea that the samples are firstly classified into subsamples by a classifier and then…

Instrumentation and Methods for Astrophysics · Physics 2019-12-05 Yanxia Zhang , Jingyi Zhang , Xin Jin , Yongheng Zhao

We present a new algorithm to estimate quasar photometric redshifts (photo-$z$s), by considering the asymmetries in the relative flux distributions of quasars. The relative flux models are built with multivariate Skew-t distributions in the…

We conduct a comprehensive study of the effects of incorporating galaxy morphology information in photometric redshift estimation. Using machine learning methods, we assess the changes in the scatter and catastrophic outlier fraction of…

Studying the cosmological sources at their cosmological rest-frames is crucial to track the cosmic history and properties of compact objects. In view of the increasing data volume of existing and upcoming telescopes/detectors, we here…

High Energy Astrophysical Phenomena · Physics 2022-01-11 F. Rastegar Nia , M. T. Mirtorabi , R. Moradi , A. Vafaei. Sadr , Y. Wang

High-redshift quasars are important to study galaxy and active galactic nuclei (AGN) evolution, test cosmological models, and study supermassive black hole growth. Optical searches for high-redshift sources have been very successful, but…

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