ODIN: Spectroscopic Validation of Ly$\alpha$-Emitting Galaxy Samples with DESI
Abstract
The One-hundred-deg^2 DECam Imaging in Narrowbands (ODIN) survey is conducting the widest-field deep narrow-band imaging of the equatorial and southern skies. ODIN uses three custom-built narrow-band (NB) filters that sample Lya-emitting galaxies (LAEs) within thin cosmic slices centered at z=2.4, 3.1, and 4.5. In this work, we utilize extensive DESI spectroscopy of ODIN-selected galaxies in the COSMOS and XMM-LSS fields to validate our LAE selection. 2-4 hr exposures with DESI yielded redshift confirmation of 3,075 ODIN LAE candidates with NB magnitudes brighter than 26~mag. Restricting to objects that yield high-confidence redshifts, the confirmation rates are (93, 96, 92)% at z=(2.4, 3.1, 4.5). The primary contaminants consist of active galactic nuclei at the expected Lya redshift range and lower redshifts (C IV, C III]), with the remainder being star-forming galaxies ([O II] and [O III]). We find minimal contamination from [O II] emitters in our sample (<~1%), implying that our REW>20 A narrow-band excess photometry requirement is sufficient to remove them.
Cite
@article{arxiv.2603.09905,
title = {ODIN: Spectroscopic Validation of Ly$\alpha$-Emitting Galaxy Samples with DESI},
author = {Ethan Pinarski and Govind Ramgopal and Nicole Firestone and Kyoung-Soo Lee and Eric Gawiser and Arjun Dey and A. Raichoor and Francisco Valdes and Robin Ciardullo and Jessica N. Aguilar and S. Ahlen and D. Bianchi and D. Brooks and F. J. Castander and M. Candela Cerdosino and T. Claybaugh and A. Cuceu and K. S. Dawson and A. de la Macorra and P. Doel and S. Ferraro and A. Font-Ribera and J. E. Forero-Romero and E. Gaztañaga and S. Gontcho A Gontcho and Lucia Guaita and G. Gutierrez and Stephen Gwyn and H. K. Herrera-Alcantar and Ho Seong Hwang and R. Joyce and S. Juneau and R. Kehoe and D. Kirkby and T. Kisner and A. Kremin and Ankit Kumar and C. Lamman and M. Landriau and L. Le Guillou and M. E. Levi and Yufeng Luo and M. Manera and P. Martini and A. Meisner and R. Miquel and J. Moustakas and A. D. Myers and S. Nadathur and Gautam R. Nagaraj and N. Palanque-Delabrouille and Changbom Park and W. J. Percival and I. Pérez-Ràfols and F. Prada and G. Rossi and E. Sanchez and Marcin Sawicki and D. Schlegel and M. Schubnell and J. Silber and Hyunmi Song and D. Sprayberry and G. Tarlé and Paulina Troncoso Iribarren and B. A. Weaver and Yujin Yang and Ann Zabludoff},
journal= {arXiv preprint arXiv:2603.09905},
year = {2026}
}
Comments
15 pages, 6 figures, Submitted to Astrophysical Journal