Matter power spectrum and the challenge of percent accuracy
Future galaxy surveys require one percent precision in the theoretical knowledge of the power spectrum over a large range including very nonlinear scales. While this level of accuracy is easily obtained in the linear regime with perturbation theory, it represents a serious challenge for small scales...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
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IOP Publishing
2016
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| Online Access: | https://eprints.nottingham.ac.uk/36366/ |
| _version_ | 1848795273952755712 |
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| author | Schneider, Aurel Teyssier, Romain Potter, Doug Stadel, Joachim Onions, Julian Reed, Darren S. Smith, Robert E. Springel, Volker Pearce, Frazer R. Scoccimarro, Roman |
| author_facet | Schneider, Aurel Teyssier, Romain Potter, Doug Stadel, Joachim Onions, Julian Reed, Darren S. Smith, Robert E. Springel, Volker Pearce, Frazer R. Scoccimarro, Roman |
| author_sort | Schneider, Aurel |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Future galaxy surveys require one percent precision in the theoretical knowledge of the power spectrum over a large range including very nonlinear scales. While this level of accuracy is easily obtained in the linear regime with perturbation theory, it represents a serious challenge for small scales where numerical simulations are required. In this paper we quantify the precision of present-day N-body methods, identifying main potential error sources from the set-up of initial conditions to the measurement of the final power spectrum. We directly compare three widely used N-body codes, Ramses, Pkdgrav3, and Gadget3 which represent three main discretisation techniques: the particle-mesh method, the tree method, and a hybrid combination of the two. For standard run parameters, the codes agree to within one percent at k ≤ 1 hMpc‾1 and to within three percent at k ≤ 10 hMpc‾1. We also consider the bispectrum and show that the reduced bispectra agree at the subpercent level for k ≤ 2 hMpc‾1. In a second step, we quantify potential errors due to initial conditions, box size, and resolution using an extended suite of simulations performed with our fastest code Pkdgrav3. We demonstrate that the simulation box size should not be smaller than L = 0:5 h‾1Gpc to avoid systematic finite-volume effects (while much larger boxes are required to beat down the statistical sample variance). Furthermore, a maximum particle mass of Mp = 10⁹ h‾1Mʘ is required to conservatively obtain one percent precision of the matter power spectrum. As a consequence, numerical simulations covering large survey volumes of upcoming missions such as DES, LSST, and Euclid will need more than a trillion particles to reproduce clustering properties at the targeted accuracy. |
| first_indexed | 2025-11-14T19:29:29Z |
| format | Article |
| id | nottingham-36366 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| last_indexed | 2025-11-14T19:29:29Z |
| publishDate | 2016 |
| publisher | IOP Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-363662020-05-04T17:45:02Z https://eprints.nottingham.ac.uk/36366/ Matter power spectrum and the challenge of percent accuracy Schneider, Aurel Teyssier, Romain Potter, Doug Stadel, Joachim Onions, Julian Reed, Darren S. Smith, Robert E. Springel, Volker Pearce, Frazer R. Scoccimarro, Roman Future galaxy surveys require one percent precision in the theoretical knowledge of the power spectrum over a large range including very nonlinear scales. While this level of accuracy is easily obtained in the linear regime with perturbation theory, it represents a serious challenge for small scales where numerical simulations are required. In this paper we quantify the precision of present-day N-body methods, identifying main potential error sources from the set-up of initial conditions to the measurement of the final power spectrum. We directly compare three widely used N-body codes, Ramses, Pkdgrav3, and Gadget3 which represent three main discretisation techniques: the particle-mesh method, the tree method, and a hybrid combination of the two. For standard run parameters, the codes agree to within one percent at k ≤ 1 hMpc‾1 and to within three percent at k ≤ 10 hMpc‾1. We also consider the bispectrum and show that the reduced bispectra agree at the subpercent level for k ≤ 2 hMpc‾1. In a second step, we quantify potential errors due to initial conditions, box size, and resolution using an extended suite of simulations performed with our fastest code Pkdgrav3. We demonstrate that the simulation box size should not be smaller than L = 0:5 h‾1Gpc to avoid systematic finite-volume effects (while much larger boxes are required to beat down the statistical sample variance). Furthermore, a maximum particle mass of Mp = 10⁹ h‾1Mʘ is required to conservatively obtain one percent precision of the matter power spectrum. As a consequence, numerical simulations covering large survey volumes of upcoming missions such as DES, LSST, and Euclid will need more than a trillion particles to reproduce clustering properties at the targeted accuracy. IOP Publishing 2016-04-26 Article PeerReviewed Schneider, Aurel, Teyssier, Romain, Potter, Doug, Stadel, Joachim, Onions, Julian, Reed, Darren S., Smith, Robert E., Springel, Volker, Pearce, Frazer R. and Scoccimarro, Roman (2016) Matter power spectrum and the challenge of percent accuracy. Journal of Cosmology and Astroparticle Physics, 2016 (04). 047-047. ISSN 1475-7516 Cosmological Simulations Power Spectrum http://iopscience.iop.org/article/10.1088/1475-7516/2016/04/047/meta doi:10.1088/1475-7516/2016/04/047 doi:10.1088/1475-7516/2016/04/047 |
| spellingShingle | Cosmological Simulations Power Spectrum Schneider, Aurel Teyssier, Romain Potter, Doug Stadel, Joachim Onions, Julian Reed, Darren S. Smith, Robert E. Springel, Volker Pearce, Frazer R. Scoccimarro, Roman Matter power spectrum and the challenge of percent accuracy |
| title | Matter power spectrum and the challenge of percent accuracy |
| title_full | Matter power spectrum and the challenge of percent accuracy |
| title_fullStr | Matter power spectrum and the challenge of percent accuracy |
| title_full_unstemmed | Matter power spectrum and the challenge of percent accuracy |
| title_short | Matter power spectrum and the challenge of percent accuracy |
| title_sort | matter power spectrum and the challenge of percent accuracy |
| topic | Cosmological Simulations Power Spectrum |
| url | https://eprints.nottingham.ac.uk/36366/ https://eprints.nottingham.ac.uk/36366/ https://eprints.nottingham.ac.uk/36366/ |