DOE OSTI · 1997871
Target Selection and Sample Characterization for the DESI LOW-Z Secondary Target Program
Abstract
Abstract We introduce the DESI LOW- Z Secondary Target Survey, which combines the wide-area capabilities of the Dark Energy Spectroscopic Instrument (DESI) with an efficient, low-redshift target selection method. Our selection consists of a set of color and surface brightness cuts, combined with modern machine-learning methods, to target low-redshift dwarf galaxies ( z < 0.03) between 19 < r < 21 with high completeness. We employ a convolutional neural network (CNN) to select high-priority targets. The LOW- Z survey has already obtained over 22,000 redshifts of dwarf galaxies ( M * < 10 9 M ⊙ ), comparable to the number of dwarf galaxies discovered in the Sloan Digital Sky Survey DR8 and GAMA. As a spare fiber survey, LOW- Z currently receives fiber allocation for just ∼50% of its targets. However, we estimate that our selection is highly complete: for galaxies at z < 0.03 within our magnitude limits, we achieve better than 95% completeness with ∼1% efficiency using catalog-level photometric cuts. We also demonstrate that our CNN selections z < 0.03 galaxies from the photometric cuts subsample at least 10 times more efficiently while maintaining high completeness. The full 5 yr DESI program will expand the LOW- Z sample, densely mapping the low-redshift Universe, providing an unprecedented sample of dwarf galaxies, and providing critical information about how to pursue effective and efficient low-redshift surveys.
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Darragh-Ford, Elise (ORCID:0000000288005652), Wu, John F. (ORCID:000000025077881X), Mao, Yao-Yuan (ORCID:0000000212000820), Wechsler, Risa H. (ORCID:000000032229011X), Geha, Marla (ORCID:0000000270079725), Forero-Romero, Jaime E. (ORCID:0000000228903725), Hahn, ChangHoon (ORCID:0000000311970902), Kallivayalil, Nitya (ORCID:0000000232041742), Moustakas, John (ORCID:0000000227334559), Nadler, Ethan O. (ORCID:0000000211823825), Nowotka, Marta, Peek, J. E. G. (ORCID:0000000347977030), Tollerud, Erik J. (ORCID:000000029599310X), Weiner, Benjamin (ORCID:0000000160657483), Aguilar, J. (ORCID:000000030822452X), Ahlen, S. (ORCID:0000000160987247), Brooks, D. (ORCID:0000000284585047), Cooper, A. P. (ORCID:000000018274158X), de la Macorra, A., Dey, A. (ORCID:0000000249284003), Fanning, K., Font-Ribera, A. (ORCID:0000000230337312), Gontcho A Gontcho, S. (ORCID:000000033142233X), Honscheid, K., Kisner, T. (ORCID:0000000335107134), Kremin, Anthony (ORCID:0000000163567424), Landriau, M. (ORCID:0000000318388528), Levi, Michael E. (ORCID:0000000318871018), Martini, P. (ORCID:0000000201944017), Meisner, Aaron M. (ORCID:0000000211257384), Miquel, R. (ORCID:0000000266104836), Myers, Adam D., Nie, Jundan (ORCID:0000000165908122), Palanque-Delabrouille, N. (ORCID:000000033188784X), Percival, W. J. (ORCID:0000000206445727), Prada, F. (ORCID:0000000171458674), Schlegel, D. (ORCID:0000000250425088), Schubnell, M., Tarlé, Gregory (ORCID:0000000317040781), Vargas-Magaña, M., Zhou, Zhimin (ORCID:0000000241350977), Zou, H. (ORCID:0000000266843997). 2023-09-01. Target Selection and Sample Characterization for the DESI LOW-Z Secondary Target Program. https://doi.org/10.3847/1538-4357%2Face902
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