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Galaxy Clustering with LSST: Effects of Number Count Bias from Blending

Journal Article · · The Open Journal of Astrophysics
DOI:https://doi.org/10.33232/001c.136427· OSTI ID:3008298
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8]
  1. Stony Brook Univ., NY (United States); Univ. of Chicago, IL (United States)
  2. Space Telescope Science Institute, Baltimore, MD (United States); Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
  3. Univ. of Chicago, IL (United States). Kavli Inst. for Cosmological Physics (KICP)
  4. Stony Brook Univ., NY (United States)
  5. Dillard Univ., New Orleans, LA (United States)
  6. Rutgers Univ., Piscataway, NJ (United States)
  7. Cornell Univ., Ithaca, NY (United States)
  8. Imperial College, London (United Kingdom)
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The Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will survey the southern sky to create the largest galaxy catalog to date, and its statistical power demands an improved understanding of systematic effects such as source overlaps, also known as blending. In this work we study how blending introduces a bias in the number counts of galaxies (instead of the flux and colors), and how it propagates into galaxy clustering statistics. We use the 300 deg2 DC2 image simulation and its resulting galaxy catalog (LSST Dark Energy Science Collaboration et al. 2021) to carry out this study. We find that, for a LSST Year 1 (Y1)-like cosmological analyses, the number count bias due to blending leads to small but statistically significant differences in mean redshift measurements when comparing an observed sample to an unblended calibration sample. In the two-point correlation function, blending causes differences greater than 3σ on scales below approximately 10', but large scales are unaffected. We fit Ωm and linear galaxy bias in a Bayesian cosmological analysis and find that the recovered parameters from this limited area sample, with the LSST Y1 scale cuts, are largely unaffected by blending. Our main results hold when considering photometric redshift and a LSST Year 5 (Y5)-like sample.
Research Organization:
Baltimore, Space Telescope Sci.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP; Cornell U., Phys. Dept.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Imperial Coll., London; New Orleans U.; Rutgers U., Piscataway; SUNY, Stony Brook; Univ. of Chicago, IL (United States)
Sponsoring Organization:
US Department of Energy; USDOE Office of Science (SC), High Energy Physics (HEP)
Grant/Contract Number:
89243024CSC000002; AC02-05CH11231; AC02-07CH11359; AC02-76SF00515; SC0009924; SC0010008; SC0021949; SC0023387; SC0025309
OSTI ID:
3008298
Alternate ID(s):
OSTI ID: 2479775
Report Number(s):
FERMILAB-PUB-24-0864-V
Journal Information:
The Open Journal of Astrophysics, Journal Name: The Open Journal of Astrophysics Vol. 8; ISSN 2565-6120
Publisher:
Maynooth Academic PublishingCopyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
LSST
Vera C. Rubin Observatory
cosmological parameters
cosmology
dark energy
extragalactic astrophysics
large-scale structure of the universe