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Title: Unbiased clustering estimates with the DESI fibre assignment

Abstract

The Emission Line Galaxy survey made by the Dark Energy Spectroscopic Instrument (DESI) survey will be created from five passes of the instrument on the sky. On each pass, the constrained mobility of the ends of the fibres in the DESI focal plane means that the angular distribution of targets that can be observed is limited. Thus, the clustering of samples constructed using a limited number of passes will be strongly affected by missing targets. In two recent papers, we showed how the effect of missing galaxies can be corrected when calculating the correlation function using a weighting scheme for pairs. Using mock galaxy catalogues we now show that this method provides an unbiased estimator of the true correlation function for the DESI survey after any number of passes. We use multiple mocks to determine the expected errors given one to four passes, compared to an idealized survey observing an equivalent number of randomly selected targets. On BAO scales, we find that the error is a factor of 2 worse after one pass, but that after three or more passes, the errors are very similar. Thus, we find that the fibre assignment strategy enforced by the design of DESI willmore » not affect the cosmological measurements to be made by the survey, and can be removed as a potential risk for this experiment.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6];  [5]; ORCiD logo [7];  [8]
  1. Univ. of Portsmouth (United Kingdom)
  2. Yale Univ., New Haven, CT (United States)
  3. Univ. of Portsmouth (United Kingdom); Univ. of Waterloo, ON (Canada); Perimeter Inst. for Theoretical Physics, Waterloo, ON (Canada)
  4. Univ. College London (United Kingdom)
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  6. Univ. de los Andes, Bogota (Colombia)
  7. The Ohio State Univ., Columbus, OH (United States)
  8. Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE
OSTI Identifier:
1471256
Alternate Identifier(s):
OSTI ID: 1543969
Grant/Contract Number:  
AC02-05CH1123
Resource Type:
Published Article
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 481; Journal Issue: 2; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy & Astrophysics

Citation Formats

Bianchi, Davide, Burden, Angela, Percival, Will J., Brooks, David, Cahn, Robert N., Forero-Romero, Jaime E., Levi, Michael, Ross, Ashley J., and Tarle, Gregory. Unbiased clustering estimates with the DESI fibre assignment. United States: N. p., 2018. Web. doi:10.1093/mnras/sty2377.
Bianchi, Davide, Burden, Angela, Percival, Will J., Brooks, David, Cahn, Robert N., Forero-Romero, Jaime E., Levi, Michael, Ross, Ashley J., & Tarle, Gregory. Unbiased clustering estimates with the DESI fibre assignment. United States. doi:10.1093/mnras/sty2377.
Bianchi, Davide, Burden, Angela, Percival, Will J., Brooks, David, Cahn, Robert N., Forero-Romero, Jaime E., Levi, Michael, Ross, Ashley J., and Tarle, Gregory. Fri . "Unbiased clustering estimates with the DESI fibre assignment". United States. doi:10.1093/mnras/sty2377.
@article{osti_1471256,
title = {Unbiased clustering estimates with the DESI fibre assignment},
author = {Bianchi, Davide and Burden, Angela and Percival, Will J. and Brooks, David and Cahn, Robert N. and Forero-Romero, Jaime E. and Levi, Michael and Ross, Ashley J. and Tarle, Gregory},
abstractNote = {The Emission Line Galaxy survey made by the Dark Energy Spectroscopic Instrument (DESI) survey will be created from five passes of the instrument on the sky. On each pass, the constrained mobility of the ends of the fibres in the DESI focal plane means that the angular distribution of targets that can be observed is limited. Thus, the clustering of samples constructed using a limited number of passes will be strongly affected by missing targets. In two recent papers, we showed how the effect of missing galaxies can be corrected when calculating the correlation function using a weighting scheme for pairs. Using mock galaxy catalogues we now show that this method provides an unbiased estimator of the true correlation function for the DESI survey after any number of passes. We use multiple mocks to determine the expected errors given one to four passes, compared to an idealized survey observing an equivalent number of randomly selected targets. On BAO scales, we find that the error is a factor of 2 worse after one pass, but that after three or more passes, the errors are very similar. Thus, we find that the fibre assignment strategy enforced by the design of DESI will not affect the cosmological measurements to be made by the survey, and can be removed as a potential risk for this experiment.},
doi = {10.1093/mnras/sty2377},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 2,
volume = 481,
place = {United States},
year = {2018},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1093/mnras/sty2377

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