Characterizing the target selection pipeline for the Dark Energy Spectroscopic Instrument Bright Galaxy Survey

Ruiz-Macias, Omar; Zarrouk, Pauline; Cole, Shaun; Baugh, C. M.; Norberg, Peder; Lucey, J. R.; Dey, Arjun; Eisenstein, Daniel J.; Doel, P.; Gaztañaga, E.; Hahn, ChangHoon; Kehoe, R.; Kitanidis, Ellie; Landriau, Martin; Lang, Dustin; Moustakas, John; Myers, Adam D.; Prada, Francisco; Schubnell, M.; Weinberg, David H.; Wilson, Michael J.

doi:10.1093/mnras/stab292

Cited by 23 publications

(24 citation statements)

References 30 publications

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“…A candidate BGS selection using DR8 DECaLS was first explored in (Ruiz-Macias et al 2021) and also in a research note (Ruiz-Macias et al 2020). The core of this selection for the bright sample remains unchanged: a bright sample at 𝑟 < 19.5 (BGS Bright) and a faint sample at 19.5 < 𝑟 < 20 (BGS Faint).…”

Section: Bgs Target Catalogue Using Dr9mentioning

confidence: 99%

“…In Section 2.3, we investigate the consequences of such a change in the BGS selection (ii) Large galaxies: the size of the masking radius around large galaxies in DR9 has increased from roughly 10 arsec to 30 arcsec, however the pre-fitting for large sources led to major improvements in the photometry extraction of these objects which allows us not to apply this mask in DR9. Moreover, we remind the reader that in (Ruiz-Macias et al 2021), we assess the completeness of the previous selection using DR8 by matching the BGS targets with GAMA DR4 and found that we were missing about 25 true galaxies/deg 2 .…”

Section: Changes In the Bgs Target Selectionmentioning

confidence: 99%

“…(iii) Quality cuts (QC): the "quality cuts" (QC) defined in (Ruiz-Macias et al 2021) for DECaLS DR8 are cuts in FRACMASKED_𝑖 < 0.4, FRACIN_𝑖 > 0.3, FRACFLUX_𝑖 < 5, where 𝑖 ≡ 𝑔, 𝑟 or 𝑧. FRACIN is used to select sources for which a large fraction of the model flux lies within the contiguous pixels to which the model was fitted, FRACFLUX is used to reject objects that are swamped by flux from adjacent sources, and FRACMASKED is used to veto objects with a high fraction of masked pixels. The overall improvement in the quality of the photometry assessed in next sections 2.1.4 and 2.1.3 allows us to adopt a less conservative definition of the QC.…”

Section: Changes In the Bgs Target Selectionmentioning

confidence: 99%

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confidence: 99%

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Preliminary clustering properties of the DESI BGS bright targets using DR9 Legacy Imaging Surveys

Zarrouk

Ruiz-Macias

Cole

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We characterise the selection cuts and clustering properties of a magnitude-limited sample of bright galaxies that is part of the Bright Galaxy Survey (BGS) of the Dark Energy Spectroscopic Instrument (DESI) using the ninth data release of the Legacy Imaging Surveys (DR9). We describe changes in the DR9 selection compared to the DR8 one and we also compare the DR9 selection in three distinct regions: BASS/MzLS in the north Galactic Cap (NGC), DECaLS in the NGC, and DECaLS in the south Galactic Cap (SGC). We investigate the systematics associated with the selection and assess its completeness by matching the BGS targets with the Galaxy and Mass Assembly (GAMA) survey. We measure the angular clustering for the overall bright sample (rmag ≤ 19.5) and as function of apparent magnitude and colour. This enables to determine the clustering strength r0 and slope γ by fitting a power-law model that can be used to generate accurate mock catalogues for this tracer. We use a counts-in-cells technique to explore higher-order statistics and cross-correlations with external spectroscopic data sets in order to check the evolution of the clustering with redshift and the redshift distribution of the BGS targets using clustering-redshifts. While this work validates the properties of the BGS bright targets, the final target selection pipeline and clustering properties of the entire DESI BGS will be fully characterised and validated with the spectroscopic data of Survey Validation.

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Section: Bgs Target Catalogue Using Dr9mentioning

confidence: 99%

Section: Changes In the Bgs Target Selectionmentioning

confidence: 99%

Section: Changes In the Bgs Target Selectionmentioning

confidence: 99%

“…

…”

mentioning

confidence: 99%

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Preliminary clustering properties of the DESI BGS bright targets using DR9 Legacy Imaging Surveys

Zarrouk

Ruiz-Macias

Cole

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…While this kind of bias may be expected, it is important to characterize and take into account. One solution is to acquire more training data where current data are sparse; in the future, we will be able to alleviate the CNN biases by incorporating data from massively multiplexed spectroscopic surveys such as the DESI Surveys (DESI Collaboration et al 2016;Ruiz-Macias et al 2021;E. Darragh-Ford et al, in preparation).…”

Section: Cross-validationmentioning

confidence: 99%

Extending the SAGA Survey (xSAGA) I: Satellite Radial Profiles as a Function of Host Galaxy Properties

Wu,

Peek,

Tollerud

et al. 2021

Preprint

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We present "Extending the Satellites Around Galactic Analogs Survey" (xSAGA), a method for identifying low-z galaxies on the basis of optical imaging, and results on the spatial distributions of xSAGA satellites around host galaxies. Using spectroscopic redshift catalogs from the SAGA Survey as a training data set, we have optimized a convolutional neural network (CNN) to identify z < 0.03 galaxies from more distant objects using image cutouts from the DESI Legacy Imaging Surveys. From the sample of > 100, 000 CNN-selected low-z galaxies, we identify > 20, 000 probable satellites located between 36-300 projected kpc from NASA-Sloan Atlas central galaxies in the stellar mass range 9.5 < log(M /M ) < 11. We characterize the incompleteness and contamination for CNN-selected samples, and apply corrections in order to estimate the true number of satellites as a function of projected radial distance from their hosts. Satellite richness depends strongly on host stellar mass, such that more massive host galaxies have more satellites, and on host morphology, such that elliptical hosts have more satellites than disky hosts with comparable stellar masses. We also find a strong inverse correlation between satellite richness and the magnitude gap between a host and its brightest satellite. The normalized satellite radial distribution between 36-300 kpc does not depend strongly on host stellar mass, morphology, or magnitude gap. The satellite abundances and radial distributions we measure are in reasonable agreement with predictions from hydrodynamic simulations. Our results deliver unprecedented statistical power for studying satellite galaxy populations, and highlight the promise of using machine learning for extending galaxy samples of wide-area surveys.

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The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000

Brouwer

Oman²,

Valentijn³

et al. 2021

A&A

130

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We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter (gbar) with the observed gravitational acceleration (gobs), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in gobs into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde’s emergent gravity (EG). We find that the measured relation between gobs and gbar agrees well with the MG predictions. In addition, we find a difference of at least 6σ between the RARs of early- and late-type galaxies (split by Sérsic index and u − r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant (Mgas ≈ M⋆) circumgalactic gaseous haloes. The observed behaviour is also expected in Λ-cold dark matter (ΛCDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a ΛCDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas; current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and ΛCDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.

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Characterizing the target selection pipeline for the Dark Energy Spectroscopic Instrument Bright Galaxy Survey

Cited by 23 publications

References 30 publications

Preliminary clustering properties of the DESI BGS bright targets using DR9 Legacy Imaging Surveys

Preliminary clustering properties of the DESI BGS bright targets using DR9 Legacy Imaging Surveys

Extending the SAGA Survey (xSAGA) I: Satellite Radial Profiles as a Function of Host Galaxy Properties

The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000

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