Owl-z: a Bayesian tool to select z \geq 7 quasars
Meriam Ezziati, Roser Pello, Jean-Gabriel Cuby, Pierre Pudlo, Fran\c{c}ois-Xavier Dup\'e, Jean-Charles Lambert, Jean-Charles Cuillandre, Olivier Ilbert, Sylvain de la Torre, St\'ephane Arnouts, Eric Jullo, Daming Yang

TL;DR
Owl-z is a Bayesian tool designed to identify high-redshift quasars (z ≥ 7) in wide-field surveys, effectively distinguishing them from contaminants like brown dwarfs and early-type galaxies, and adaptable to various surveys.
Contribution
The paper introduces Owl-z, a versatile Bayesian code that accurately identifies z ≥ 7 quasars and contaminants, validated on multiple datasets and adaptable to different survey data.
Findings
Owl-z successfully re-identified all known z ≥ 7 quasars in validation.
The code achieves full performance for bright sources (H_E ≲ 22).
Adjustable probability thresholds optimize candidate selection.
Abstract
This paper presents Owl-z, a Bayesian code aiming at identifying z \geq 7 quasars in wide field optical and near-infrared surveys. By construction,the code can also be used to select objects that contaminate the high-z quasar population, i.e. brown dwarfs and early-type galaxies at intermediate redshifts. The code can be adapted for the selection of high-z galaxies, and although it has been tuned to the Euclid Wide Survey, it can be easily adapted to other photometric surveys. The code input data are the object's photometric data and its galactic longitude and latitude, and the code output data are the probabilities of the modelled populations of high-z quasars, brown dwarfs and early-type galaxies at intermediate redshift. As part of the validation, Owl-z could re-identify all spectroscopically confirmed quasars at z \geq 7, demonstrating the code's versatility in applying to different…
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Taxonomy
TopicsGalaxies: Formation, Evolution, Phenomena · Gaussian Processes and Bayesian Inference · Astronomy and Astrophysical Research
