Information content of higher order galaxy correlation functions

Journal Article · 24 May 2021 · Monthly Notices of the Royal Astronomical Society

DOI: https://doi.org/10.1093/mnras/stab1199 · OSTI ID:1785031

Samushia, Lado ^[1]; Slepian, Zachary ^[2]; Villaescusa-Navarro, Francisco ^[3]

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1. Univ., Manhattan, KS (United States); Abastumani Astrophysical Observatory (Georgia)
2. Univ. of Florida, Gainesville, FL (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
3. Princeton Univ., NJ (United States); Flatiron Institute, New York, NY (United States)

The shapes of galaxy N-point correlation functions can be used as standard rulers to constrain the distance–redshift relationship. The cosmological density fields traced by late-time galaxy formation are initially nearly Gaussian, and hence, all the cosmological information can be extracted from their two-point correlation function. Subsequent non-linear evolution under gravity, as well as halo and then galaxy formation, generates higher order correlation functions. Since the mapping of the initial to the final density field is, on large scales, invertible, it is often claimed that the information content of the initial field’s power spectrum is equal to that of all the higher order functions of the final, non-linear field. This claim implies that reconstruction of the initial density field from the non-linear field renders analysis of higher order correlation functions of the latter superfluous. We show that this claim is false when the N-point functions are used as standard rulers. Constraints available from joint analysis of the two and three-point correlation functions can, in some cases, exceed those offered by the initial power spectrum. We provide a mathematical justification for this claim and demonstrate it using a large suite of N-body simulations. In particular, we show that for the z = 0 real-space matter field in the limit of vanishing shot-noise, taking modes up to k_max = 0.2 h Mpc⁻¹, using the bispectrum alone offers a factor of 2 reduction in the variance on the cosmic distance scale relative to that available from the linear power spectrum.

• Research Organization: Kansas State Univ., Manhattan, KS (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC); USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: SC0011840; SC0021165
• OSTI ID: 1785031
• Journal Information: Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 1 Vol. 505; ISSN 1365-2966; ISSN 0035-8711
• Publisher: Oxford University PressCopyright Statement
• Country of Publication: United States
• Language: English