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arXiv · 2208.08511

Target Selection and Validation of DESI Quasars

Edmond Chaussidon·Christophe Yèche·Nathalie Palanque-Delabrouille·David M. Alexander·Jinyi Yang·Steven Ahlen·Stephen. Bailey·David Brooks·Zheng Cai·Solène Chabanier·Tamara M. Davis·Kyle Dawson·Axel de la Macorra·Arjun Dey·Biprateep Dey·Sarah Eftekharzadeh·Daniel J. Eisenstein·Kevin Fanning·Andreu Font-Ribera·Enrique Gaztañaga·Satya Gontcho A Gontcho·Alma X. Gonzalez-Morales·Julien Guy·Hiram K. Herrera-Alcantar·Klaus Honscheid·Mustapha Ishak·Linhua Jiang·Stephanie Juneau·Robert Kehoe·Theodore Kisner·Andras Kovács·Anthony Kremin·Ting-Wen Lan·Martin Landriau·Laurent Le Guillou·Michael E. Levi·Christophe Magneville·Paul Martini·Aaron M. Meisner·John Moustakas·Andrea Muñoz-Gutiérrez·Adam D. Myers·Jeffrey A. Newman·Jundan Nie·Will J. Percival·Claire Poppett·Francisco Prada·Anand Raichoor·Corentin Ravoux·Ashley J. Ross·Edward Schlafly·David Schlegel·Ting Tan·Gregory Tarlé·Rongpu Zhou·Zhimin Zhou·Hu Zou
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Abstract

The Dark Energy Spectroscopic Instrument (DESI) survey will measure large-scale structures using quasars as direct tracers of dark matter in the redshift range 0.9 2.1. We present several methods to select candidate quasars for DESI, using input photometric imaging in three optical bands (g, r, z) from the DESI Legacy Imaging Surveys and two infrared bands (W1, W2) from the Wide-field Infrared Explorer (WISE). These methods were extensively tested during the Survey Validation of DESI. In this paper, we report on the results obtained with the different methods and present the selection we optimized for the DESI main survey. The final quasar target selection is based on a Random Forest algorithm and selects quasars in the magnitude range 16.5 99% purity for a nominal effective exposure time of ~1000s. With a 310 per sq. deg. target density, the main selection allows DESI to select more than 200 QSOs per sq. deg. (including 60 quasars with z>2.1), exceeding the project requirements by 20%. The redshift distribution of the selected quasars is in excellent agreement with quasar luminosity function predictions.

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Edmond Chaussidon, Christophe Yèche, Nathalie Palanque-Delabrouille, David M. Alexander, Jinyi Yang, Steven Ahlen, Stephen. Bailey, David Brooks, Zheng Cai, Solène Chabanier, Tamara M. Davis, Kyle Dawson, Axel de la Macorra, Arjun Dey, Biprateep Dey, Sarah Eftekharzadeh, Daniel J. Eisenstein, Kevin Fanning, Andreu Font-Ribera, Enrique Gaztañaga, Satya Gontcho A Gontcho, Alma X. Gonzalez-Morales, Julien Guy, Hiram K. Herrera-Alcantar, Klaus Honscheid, Mustapha Ishak, Linhua Jiang, Stephanie Juneau, Robert Kehoe, Theodore Kisner, Andras Kovács, Anthony Kremin, Ting-Wen Lan, Martin Landriau, Laurent Le Guillou, Michael E. Levi, Christophe Magneville, Paul Martini, Aaron M. Meisner, John Moustakas, Andrea Muñoz-Gutiérrez, Adam D. Myers, Jeffrey A. Newman, Jundan Nie, Will J. Percival, Claire Poppett, Francisco Prada, Anand Raichoor, Corentin Ravoux, Ashley J. Ross, Edward Schlafly, David Schlegel, Ting Tan, Gregory Tarlé, Rongpu Zhou, Zhimin Zhou, Hu Zou. 2022-08-19. Target Selection and Validation of DESI Quasars. https://doi.org/10.3847/1538-4357%2Facb3c2

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