Methods for studying the accuracy of light propagation in N -body simulations

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Methods for studying the accuracy of light propagation in N -body simulations. / Koksbang, S. M.; Hannestad, S.

In: Physical Review D, Vol. 91, 2015, p. 43508.

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Koksbang, S. M. ; Hannestad, S. / Methods for studying the accuracy of light propagation in N -body simulations. In: Physical Review D. 2015 ; Vol. 91. pp. 43508.

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@article{e864cf870e104ba59588354d74ab222f,
title = "Methods for studying the accuracy of light propagation in N -body simulations",
abstract = "It is proposed to use exact, cosmologically relevant solutions to Einstein's equations to accurately quantify the precision of ray tracing techniques through Newtonian N -body simulations. As an initial example of such a study, the recipe in (Green and Wald, 2012) for going between N -body results and a perturbed Friedmann-Lemaitre-Robertson-Walker (FLRW) metric in the Newtonian gauge is used to study light propagation through quasispherical Szekeres models. The study is conducted by deriving a set of ordinary differential equations (ODEs) giving an expression for the angular diameter distance in the Newtonian gauge metric. The accuracy of the results obtained from the ODEs is estimated by using the ODEs to determine the distance-redshift relation in mock N -body data based on quasispherical Szekeres models. The results are then compared to the exact relations. From this comparison it is seen that the obtained ODEs can accurately reproduce the distance-redshift relation along both radial and nonradial geodesics in spherically symmetric models. The reproduction of geodesics in nonsymmetric Szekeres models is slightly less accurate, but still good. These results indicate that the employment of perturbed FLRW metrics for standard ray tracing techniques yields fairly accurate results, at least regarding distance-redshift relations. It is possible though, that this conclusion will be rendered invalid if other typical ray tracing approximations are included and if light is allowed to travel through several structures instead of just one.",
keywords = "Cosmology, Observational cosmology, Mathematical and relativistic aspects of cosmology",
author = "Koksbang, {S. M.} and S. Hannestad",
year = "2015",
doi = "10.1103/PhysRevD.91.043508",
language = "English",
volume = "91",
pages = "43508",
journal = "Physical Review D",
issn = "2470-0010",
publisher = "american physical society",

}

RIS

TY - JOUR

T1 - Methods for studying the accuracy of light propagation in N -body simulations

AU - Koksbang, S. M.

AU - Hannestad, S.

PY - 2015

Y1 - 2015

N2 - It is proposed to use exact, cosmologically relevant solutions to Einstein's equations to accurately quantify the precision of ray tracing techniques through Newtonian N -body simulations. As an initial example of such a study, the recipe in (Green and Wald, 2012) for going between N -body results and a perturbed Friedmann-Lemaitre-Robertson-Walker (FLRW) metric in the Newtonian gauge is used to study light propagation through quasispherical Szekeres models. The study is conducted by deriving a set of ordinary differential equations (ODEs) giving an expression for the angular diameter distance in the Newtonian gauge metric. The accuracy of the results obtained from the ODEs is estimated by using the ODEs to determine the distance-redshift relation in mock N -body data based on quasispherical Szekeres models. The results are then compared to the exact relations. From this comparison it is seen that the obtained ODEs can accurately reproduce the distance-redshift relation along both radial and nonradial geodesics in spherically symmetric models. The reproduction of geodesics in nonsymmetric Szekeres models is slightly less accurate, but still good. These results indicate that the employment of perturbed FLRW metrics for standard ray tracing techniques yields fairly accurate results, at least regarding distance-redshift relations. It is possible though, that this conclusion will be rendered invalid if other typical ray tracing approximations are included and if light is allowed to travel through several structures instead of just one.

AB - It is proposed to use exact, cosmologically relevant solutions to Einstein's equations to accurately quantify the precision of ray tracing techniques through Newtonian N -body simulations. As an initial example of such a study, the recipe in (Green and Wald, 2012) for going between N -body results and a perturbed Friedmann-Lemaitre-Robertson-Walker (FLRW) metric in the Newtonian gauge is used to study light propagation through quasispherical Szekeres models. The study is conducted by deriving a set of ordinary differential equations (ODEs) giving an expression for the angular diameter distance in the Newtonian gauge metric. The accuracy of the results obtained from the ODEs is estimated by using the ODEs to determine the distance-redshift relation in mock N -body data based on quasispherical Szekeres models. The results are then compared to the exact relations. From this comparison it is seen that the obtained ODEs can accurately reproduce the distance-redshift relation along both radial and nonradial geodesics in spherically symmetric models. The reproduction of geodesics in nonsymmetric Szekeres models is slightly less accurate, but still good. These results indicate that the employment of perturbed FLRW metrics for standard ray tracing techniques yields fairly accurate results, at least regarding distance-redshift relations. It is possible though, that this conclusion will be rendered invalid if other typical ray tracing approximations are included and if light is allowed to travel through several structures instead of just one.

KW - Cosmology

KW - Observational cosmology

KW - Mathematical and relativistic aspects of cosmology

U2 - 10.1103/PhysRevD.91.043508

DO - 10.1103/PhysRevD.91.043508

M3 - Journal article

VL - 91

SP - 43508

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

ER -