The Spectroscopic Data Processing Pipeline for the Dark Energy Spectroscopic Instrument

Guy, J.; Bailey, S.; Kremin, Anthony; Alam, Shadab; Alexander, D. M.; Prieto, C. Allende; BenZvi, S.; Bolton, A.; Chaussidon, Edmond; Cooper, Andrew P.; Dawson, Kyle; Macorra, Axel de la; Dey, Arjun; Dey, Biprateep; Dhungana, G.; Eisenstein, Daniel J.; Font-Ribera, Andreu; Forero-Romero, Jaime E.; Gaztañaga, E.; Gontcho, Satya Gontcho A; Green, Dylan; Honscheid, K.; Ishak, Mustapha; Kehoe, R.; Kirkby, D.; Kisner, T. S.; Koposov, S. E.; Lan, Ting-Wen; Landriau, Martin; Guillou, L. Le; Levi, M. E.; Magneville, C.; Manser, Christopher J.; Martini, Paul; Meisner, Aaron M.; Miquel, R.; Moustakas, John; Myers, Adam D.; Newman, Jeffrey A.; Nie, Jundan; Palanque-Delabrouille, N.; Percival, Will J.; Poppett, Claire; Prada, Francisco; Raichoor, Anand; Ravoux, Corentin; Ross, Ashley J.; Schlafly, Edward F.; Schlegel, David J.; Schubnell, M.; Sharples, R. M.; Tarlè, G.; Weaver, B. A.; Yèche, Ch; Zhou, Rongpu; Zhou, Zhimin; Zou, Hu

doi:10.3847/1538-3881/acb212

Cited by 49 publications

(56 citation statements)

References 35 publications

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“…For each tile we dedicate a minimum of 40 "sky" fibers per petal to measure the sky background for accurate sky subtraction. An additional 10 fibers per petal are assigned to standard stars for flux calibration (Guy et al 2023). The rest of the "science" fibers are assigned to BGS targets on each tile according to the following fiber assignment strategy (Raichoor et al 2023).…”

Section: Fiber Assignment Strategymentioning

confidence: 99%

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The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation

Hahn

Wilson

Ruiz-Macias

et al. 2023

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Over the next 5 yr, the Dark Energy Spectroscopic Instrument (DESI) will use 10 spectrographs with 5000 fibers on the 4 m Mayall Telescope at Kitt Peak National Observatory to conduct the first Stage IV dark energy galaxy survey. At z < 0.6, the DESI Bright Galaxy Survey (BGS) will produce the most detailed map of the universe during the dark-energy-dominated epoch with redshifts of >10 million galaxies spanning 14,000 deg2. In this work, we present and validate the final BGS target selection and survey design. From the Legacy Surveys, BGS will target an r < 19.5 mag limited sample (BGS Bright), a fainter 19.5 < r < 20.175 color-selected sample (BGS Faint), and a smaller low-z quasar sample. BGS will observe these targets using exposure times scaled to achieve homogeneous completeness and cover the footprint three times. We use observations from the Survey Validation programs conducted prior to the main survey along with simulations to show that BGS can complete its strategy and make optimal use of “bright” time. BGS targets have stellar contamination <1%, and their densities do not depend strongly on imaging properties. BGS Bright will achieve >80% fiber assignment efficiency. Finally, BGS Bright and BGS Faint will achieve >95% redshift success over any observing condition. BGS meets the requirements for an extensive range of scientific applications. BGS will yield the most precise baryon acoustic oscillation and redshift-space distortion measurements at z < 0.4. It presents opportunities for new methods that require highly complete and dense samples (e.g., N-point statistics, multitracers). BGS further provides a powerful tool to study galaxy populations and the relations between galaxies and dark matter.

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Section: Fiber Assignment Strategymentioning

confidence: 99%

“…The calibrated spectra are then coadded across exposures of the same tile to produce the final processed spectra with an effective exposure time equal to t nom . The full spectroscopic data reduction is described in Guy et al (2023). We present a few examples of BGS spectra selected from the One-Percent Survey observations in Figure 7.…”

Section: Sv Observationsmentioning

confidence: 99%

The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation

Hahn

Wilson

Ruiz-Macias

et al. 2023

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“…Spectra collected by DESI are processed in a fully automatic pipeline (Guy et al 2023) and then classified by Redrock and the QSO afterburners. The spectra are binned on a wavelength array with constant linear spacing between pixels.…”

Section: Validation Samplesmentioning

confidence: 99%

“…These algorithms are dependent on Redrock output, so we rerun the QSO afterburners on the spectral samples to assess how the new templates impact their performance. Additionally, we evaluate the resulting galaxy samples, as a primary concern with improving the QSO templates is degrading the galaxy sample quality (e.g., Guy et al 2023).…”

Section: Performance On Desi Spectramentioning

confidence: 99%

Performance of the Quasar Spectral Templates for the Dark Energy Spectroscopic Instrument

Brodzeller,

Dawson,

Bailey

et al. 2023

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Millions of quasar spectra will be collected by the Dark Energy Spectroscopic Instrument (DESI), leading to a fourfold increase in the number of known quasars. High-accuracy quasar classification is essential to tighten constraints on cosmological parameters measured at the highest redshifts DESI observes (z > 2.0). We present spectral templates for identification and redshift estimation of quasars in the DESI Year 1 data release. The quasar templates are comprised of two quasar eigenspectra sets, trained on spectra from the Sloan Digital Sky Survey. The sets are specialized to reconstruct quasar spectral variation observed over separate yet overlapping redshift ranges and, together, are capable of identifying DESI quasars from 0.05 < z < 7.0. The new quasar templates show significant improvement over the previous DESI quasar templates regarding catastrophic failure rates, redshift precision and accuracy, quasar completeness, and the contamination fraction in the final quasar sample.

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“…All redshifts were determined with the Redrock pipeline (S. Bailey et al 2023, in preparation). All spectroscopy was reduced using the "Fuji" internal spectroscopic data release, which will be identical to the DESI Early Data Release (Guy et al 2023; tentatively expected in early 2023).…”

Section: The Desi Lrg Sv Samplementioning

confidence: 99%

DESI Survey Validation Spectra Reveal an Increasing Fraction of Recently Quenched Galaxies at z ∼ 1

Setton¹,

Dey²,

Khullar³

et al. 2023

ApJL

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We utilize ∼17,000 bright luminous red galaxies (LRGs) from the novel Dark Energy Spectroscopic Instrument Survey Validation spectroscopic sample, leveraging its deep (∼2.5 hr galaxy−1 exposure time) spectra to characterize the contribution of recently quenched galaxies to the massive galaxy population at 0.4 < z < 1.3. We use Prospector to infer nonparametric star formation histories and identify a significant population of recently quenched galaxies that have joined the quiescent population within the past ∼1 Gyr. The highest-redshift subset (277 at z > 1) of our sample of recently quenched galaxies represents the largest spectroscopic sample of post-starburst galaxies at that epoch. At 0.4 < z < 0.8, we measure the number density of quiescent LRGs, finding that recently quenched galaxies constitute a growing fraction of the massive galaxy population with increasing look-back time. Finally, we quantify the importance of this population among massive ( log ( M ⋆ / M ⊙ ) > 11.2) LRGs by measuring the fraction of stellar mass each galaxy formed in the gigayear before observation, f 1 Gyr. Although galaxies with f 1 Gyr > 0.1 are rare at z ∼ 0.4 (≲0.5% of the population), by z ∼ 0.8, they constitute ∼3% of massive galaxies. Relaxing this threshold, we find that galaxies with f 1 Gyr > 5% constitute ∼10% of the massive galaxy population at z ∼ 0.8. We also identify a small but significant sample of galaxies at z = 1.1–1.3 that formed with f 1 Gyr > 50%, implying that they may be analogs to high-redshift quiescent galaxies that formed on similar timescales. Future analysis of this unprecedented sample promises to illuminate the physical mechanisms that drive the quenching of massive galaxies after cosmic noon.

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The Spectroscopic Data Processing Pipeline for the Dark Energy Spectroscopic Instrument

Cited by 49 publications

References 35 publications

The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation

The DESI Bright Galaxy Survey: Final Target Selection, Design, and Validation

Performance of the Quasar Spectral Templates for the Dark Energy Spectroscopic Instrument

DESI Survey Validation Spectra Reveal an Increasing Fraction of Recently Quenched Galaxies at z ∼ 1

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