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Modeling Biased Tracers at the Field Level
In this paper, we test the perturbative halo bias model at the field level. The advantage of this approach is that any analysis can be done without sample variance if the same initial conditions are used in simulations and perturbation theory calculations. We write the bias expansion in terms of mod...
Autores principales: | , , , |
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Lenguaje: | eng |
Publicado: |
2018
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Materias: | |
Acceso en línea: | https://dx.doi.org/10.1103/PhysRevD.100.043514 http://cds.cern.ch/record/2686968 |
_version_ | 1780963606494445568 |
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author | Schmittfull, Marcel Simonović, Marko Assassi, Valentin Zaldarriaga, Matias |
author_facet | Schmittfull, Marcel Simonović, Marko Assassi, Valentin Zaldarriaga, Matias |
author_sort | Schmittfull, Marcel |
collection | CERN |
description | In this paper, we test the perturbative halo bias model at the field level. The advantage of this approach is that any analysis can be done without sample variance if the same initial conditions are used in simulations and perturbation theory calculations. We write the bias expansion in terms of modified bias operators in Eulerian space, designed such that the large bulk flows are automatically resummed and not treated perturbatively. Using these operators, the bias model accurately matches the Eulerian density of halos in N-body simulations. The mean-square model error is close to the Poisson shot noise for a wide range of halo masses, and it is rather scale independent, with scale-dependent corrections becoming relevant at the nonlinear scale. In contrast, for the linear bias, the mean-square model error can be higher than the Poisson prediction by factors of up to a few on large scales, and it becomes scale dependent already in the linear regime. We show that by weighting simulated halos by their mass, the mean-square error of the model can be further reduced by up to an order of magnitude, or by a factor of 2 when including 60% mass scatter. We also test the standard Eulerian bias model using the nonlinear matter field measured from simulations and show that it leads to a larger and more scale-dependent model error than the bias expansion based on perturbation theory. These results may be of particular relevance for cosmological inference methods that use a likelihood of the biased tracer at the field level or for initial condition and baryon acoustic oscillation reconstruction that requires a precise estimate of the large-scale potential from the biased tracer density. |
id | oai-inspirehep.net-1705454 |
institution | Organización Europea para la Investigación Nuclear |
language | eng |
publishDate | 2018 |
record_format | invenio |
spelling | oai-inspirehep.net-17054542023-10-04T07:57:49Zdoi:10.1103/PhysRevD.100.043514http://cds.cern.ch/record/2686968engSchmittfull, MarcelSimonović, MarkoAssassi, ValentinZaldarriaga, MatiasModeling Biased Tracers at the Field LevelAstrophysics and Astronomyastro-ph.COIn this paper, we test the perturbative halo bias model at the field level. The advantage of this approach is that any analysis can be done without sample variance if the same initial conditions are used in simulations and perturbation theory calculations. We write the bias expansion in terms of modified bias operators in Eulerian space, designed such that the large bulk flows are automatically resummed and not treated perturbatively. Using these operators, the bias model accurately matches the Eulerian density of halos in N-body simulations. The mean-square model error is close to the Poisson shot noise for a wide range of halo masses, and it is rather scale independent, with scale-dependent corrections becoming relevant at the nonlinear scale. In contrast, for the linear bias, the mean-square model error can be higher than the Poisson prediction by factors of up to a few on large scales, and it becomes scale dependent already in the linear regime. We show that by weighting simulated halos by their mass, the mean-square error of the model can be further reduced by up to an order of magnitude, or by a factor of 2 when including 60% mass scatter. We also test the standard Eulerian bias model using the nonlinear matter field measured from simulations and show that it leads to a larger and more scale-dependent model error than the bias expansion based on perturbation theory. These results may be of particular relevance for cosmological inference methods that use a likelihood of the biased tracer at the field level or for initial condition and baryon acoustic oscillation reconstruction that requires a precise estimate of the large-scale potential from the biased tracer density.In this paper we test the perturbative halo bias model at the field level. The advantage of this approach is that any analysis can be done without sample variance if the same initial conditions are used in simulations and perturbation theory calculations. We write the bias expansion in terms of modified bias operators in Eulerian space, designed such that the large bulk flows are automatically resummed and not treated perturbatively. Using these operators, the bias model accurately matches the Eulerian density of halos in N-body simulations. The mean-square model error is close to the Poisson shot noise for a wide range of halo masses and it is rather scale-independent, with scale-dependent corrections becoming relevant at the nonlinear scale. In contrast, for linear bias the mean-square model error can be higher than the Poisson prediction by factors of up to a few on large scales, and it becomes scale dependent already in the linear regime. We show that by weighting simulated halos by their mass, the mean-square error of the model can be further reduced by up to an order of magnitude, or by a factor of two when including $60\%$ mass scatter. We also test the Standard Eulerian bias model using the nonlinear matter field measured from simulations and show that it leads to a larger and more scale-dependent model error than the bias expansion based on perturbation theory. These results may be of particular relevance for cosmological inference methods that use a likelihood of the biased tracer at the field level, or for initial condition and BAO reconstruction that requires a precise estimate of the large-scale potential from the biased tracer density.arXiv:1811.10640oai:inspirehep.net:17054542018-11-26 |
spellingShingle | Astrophysics and Astronomy astro-ph.CO Schmittfull, Marcel Simonović, Marko Assassi, Valentin Zaldarriaga, Matias Modeling Biased Tracers at the Field Level |
title | Modeling Biased Tracers at the Field Level |
title_full | Modeling Biased Tracers at the Field Level |
title_fullStr | Modeling Biased Tracers at the Field Level |
title_full_unstemmed | Modeling Biased Tracers at the Field Level |
title_short | Modeling Biased Tracers at the Field Level |
title_sort | modeling biased tracers at the field level |
topic | Astrophysics and Astronomy astro-ph.CO |
url | https://dx.doi.org/10.1103/PhysRevD.100.043514 http://cds.cern.ch/record/2686968 |
work_keys_str_mv | AT schmittfullmarcel modelingbiasedtracersatthefieldlevel AT simonovicmarko modelingbiasedtracersatthefieldlevel AT assassivalentin modelingbiasedtracersatthefieldlevel AT zaldarriagamatias modelingbiasedtracersatthefieldlevel |