Effects of long-wavelength fluctuations in large galaxy surveys

DOI: 
10.1093/mnras/stz2194
Publication date: 
01/08/2019
Main author: 
Klypin, Anatoly
IAA authors: 
Prada, Francisco
Authors: 
Klypin, Anatoly;Prada, Francisco
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Pages: 
1684-1696
Abstract: 
In order to capture as much information as possible large galaxy surveys have been increasing their volume and redshift depth. To face this challenge theory has responded by making cosmological simulations of huge computational volumes with equally increasing the number of dark matter particles and supercomputing resources. Thus, it is taken for granted that the ideal situation is when a single computational box encompasses the whole volume of the observational survey, e.g., ̃50 h<SUP>-3</SUP>Gpc<SUP>3</SUP> for the DESI and Euclid surveys. Here we study the effects of missing long-waves in a finite volume using several relevant statistics: the abundance of dark matter halos, the PDF, the correlation function and power spectrum, and covariance matrices. Finite volume effects can substantially modify the results if the computational volumes are less than ̃(500 h<SUP>-1</SUP>Mpc)<SUP>3</SUP>. However, the effects become extremely small and practically can be ignored when the box-size exceeds ̃1 Gpc<SUP>3</SUP>. We find that the average power spectra of dark matter fluctuations show remarkable lack of dependence on the computational box-size with less than 0.1% differences between 1 h<SUP>-1</SUP>Gpc and 4 h<SUP>-1</SUP>Gpc boxes. No measurable differences are expected for the halo mass functions for these volumes. The covariance matrices are scaled trivially with volume, and small corrections due to super-sample modes can be added. We conclude that there is no need to make those extremely large simulations when a box-size of 1 - 1.5 h<SUP>-1</SUP>Gpc is sufficient to fulfil most of the survey science requirements.
Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075126683&doi=10.1093%2fmnras%2fstz2194&partnerID=40&md5=3b8e8fd34265d136a7a3abf5375e42c1
ADS Bibcode: 
2019MNRAS.489.1684K
Keywords: 
cosmology: Large scale structure;dark matter;galaxies: halos;methods: numerical;Astrophysics - Cosmology and Nongalactic Astrophysics