Refereed journal article or data article (A1)

Predicting the Redshift of Gamma-Ray Loud AGNs Using Supervised Machine Learning. II

List of Authors: Narendra Aditya, Gibson Spencer James, Dainotti Maria Giovanna, Bogdan Malgorzata, Pollo Agnieszka, Liodakis Ioannis, Poliszczuk Artem, Rinaldi Enrico

Publisher: IOP Publishing Ltd

Publication year: 2022

Journal: Astrophysical Journal Supplement


Journal acronym: ASTROPHYS J SUPPL S

Volume number: 259

Issue number: 2

Number of pages: 16

ISSN: 0067-0049

eISSN: 1538-4365



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Measuring the redshift of active galactic nuclei (AGNs) requires the use of time-consuming and expensive spectroscopic analysis. However, obtaining redshift measurements of AGNs is crucial as it can enable AGN population studies, provide insight into the star formation rate, the luminosity function, and the density rate evolution. Hence, there is a requirement for alternative redshift measurement techniques. In this project, we aim to use the Fermi Gamma-ray Space Telescope's 4LAC Data Release 2 catalog to train a machine-learning (ML) model capable of predicting the redshift reliably. In addition, this project aims at improving and extending with the new 4LAC Catalog the predictive capabilities of the ML methodology published in Dainotti et al. Furthermore, we implement feature engineering to expand the parameter space and a bias correction technique to our final results. This study uses additional ML techniques inside the ensemble method, the SuperLearner, previously used in Dainotti et al. Additionally, we also test a novel ML model called Sorted L-One Penalized Estimation. Using these methods, we provide a catalog of estimated redshift values for those AGNs that do not have a spectroscopic redshift measurement. These estimates can serve as a redshift reference for the community to verify as updated Fermi catalogs are released with more redshift measurements.

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Last updated on 2022-20-05 at 14:44