Estimating the galaxy two-point correlation function using a split random catalog - CEA - Commissariat à l’énergie atomique et aux énergies alternatives Access content directly
Journal Articles Astronomy and Astrophysics - A&A Year : 2019

Estimating the galaxy two-point correlation function using a split random catalog

E. Branchini
J. Bel
  • Function : Author
  • PersonId : 752966
  • IdHAL : julien-bel

Abstract

The two-point correlation function of the galaxy distribution is a key cosmological observable that allows us to constrain the dynamical and geometrical state of our Universe. To measure the correlation function we need to know both the galaxy positions and the expected galaxy density field. The expected field is commonly specified using a Monte-Carlo sampling of the volume covered by the survey and, to minimize additional sampling errors, this random catalog has to be much larger than the data catalog. Correlation function estimators compare data–data pair counts to data–random and random–random pair counts, where random–random pairs usually dominate the computational cost. Future redshift surveys will deliver spectroscopic catalogs of tens of millions of galaxies. Given the large number of random objects required to guarantee sub-percent accuracy, it is of paramount importance to improve the efficiency of the algorithm without degrading its precision. We show both analytically and numerically that splitting the random catalog into a number of subcatalogs of the same size as the data catalog when calculating random–random pairs and excluding pairs across different subcatalogs provides the optimal error at fixed computational cost. For a random catalog fifty times larger than the data catalog, this reduces the computation time by a factor of more than ten without affecting estimator variance or bias.
Fichier principal
Vignette du fichier
aa35828-19.pdf (380.17 Ko) Télécharger le fichier
Origin Publication funded by an institution
Loading...

Dates and versions

cea-02327633 , version 1 (22-10-2019)

Identifiers

Cite

E. Keihänen, H. Kurki-Suonio, V. Lindholm, A. Viitanen, A.-S. Suur-Uski, et al.. Estimating the galaxy two-point correlation function using a split random catalog. Astronomy and Astrophysics - A&A, 2019, 631, pp.A73. ⟨10.1051/0004-6361/201935828⟩. ⟨cea-02327633⟩
202 View
716 Download

Altmetric

Share

Gmail Mastodon Facebook X LinkedIn More