Galaxy redshift surveys with sparse sampling

Survey observations of the three-dimensional locations of galaxies are a powerful approach to measure the distribution of matter in the universe, which can be used to learn about the nature of dark energy, physics of inflation, neutrino masses, etc. A competitive survey, however, requires a large vo...

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Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2013-12, Vol.2013 (12), p.i-37
Main Authors: Chiang, Chi-Ting, Wullstein, Philipp, Jeong, Donghui, Komatsu, Eiichiro, Blanc, Guillermo A, Ciardullo, Robin, Drory, Niv, Fabricius, Maximilian, Finkelstein, Steven, Gebhardt, Karl
Format: Article
Language:English
Subjects:
ACCURACY
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CORRELATION FUNCTIONS
COSMOLOGICAL INFLATION
Covering
Dark energy
Density
Deviation
GALAXIES
NEUTRINOS
NONLUMINOUS MATTER
RED SHIFT
Sampling
Sampling methods
SPACE
SPECTRA
Surveys
TELESCOPES
Three dimensional
UNIVERSE
Window functions
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Summary:Survey observations of the three-dimensional locations of galaxies are a powerful approach to measure the distribution of matter in the universe, which can be used to learn about the nature of dark energy, physics of inflation, neutrino masses, etc. A competitive survey, however, requires a large volume (e.g., V sub(survey) ~ 10 Gpc super(3)) to be covered, and thus tends to be expensive. A "sparse sampling" method offers a more affordable solution to this problem: within a survey footprint covering a given survey volume, V sub(survey), we observe only a fraction of the volume. The distribution of observed regions should be chosen such that their separation is smaller than the length scale corresponding to the wavenumber of interest. Then one can recover the power spectrum of galaxies with precision expected for a survey covering a volume of V sub(survey) (rather than the volume of the sum of observed regions) with the number density of galaxies given by the total number of observed galaxies divided by V sub(survey) (rather than the number density of galaxies within an observed region). We find that regularly-spaced sampling yields an unbiased power spectrum with no window function effect, and deviations from regularly-spaced sampling, which are unavoidable in realistic surveys, introduce calculable window function effects and increase the uncertainties of the recovered power spectrum. On the other hand, we show that the two-point correlation function (pair counting) is not affected by sparse sampling. While we discuss the sparse sampling method within the context of the forthcoming Hobby-Eberly Telescope Dark Energy Experiment, the method is general and can be applied to other galaxy surveys.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2013/12/030