Predicted redshifts for 4FGL gamma-ray loud AGNs Virtual Observatory Resource

Authors
  1. Narendra A.
  2. Gibson S.J.
  3. Dainotti M.G.
  4. Bogdan M.
  5. Pollo A.
  6. Liodakis I.,Poliszczuk A.
  7. Rinaldi E.
  8. Published by
    CDS
Abstract

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.

Keywords
  1. active-galactic-nuclei
  2. gamma-ray-astronomy
  3. astronomical-models
  4. redshifted
Bibliographic source Bibcode
2022ApJS..259...55N
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/259/55
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJS/259/55
Document Object Identifer DOI
doi:10.26093/cds/vizier.22590055

Access

Web browser access HTML
https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/259/55
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/259/55
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/259/55
IVOA Table Access TAP
https://tapvizier.cds.unistra.fr/TAPVizieR/tap
Run SQL-like queries with TAP-enabled clients (e.g., TOPCAT).
IVOA Cone Search SCS
For use with a cone search client (e.g., TOPCAT).
https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/259/55/table3?
https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/259/55/table3?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/259/55/table3?

History

2022-07-19T08:33:14Z
Resource record created
2022-07-19T08:33:14Z
Created
2022-08-26T08:04:48Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr