Iterative removal of redshift space distortions from galaxy clustering. (arXiv:1912.03392v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wang_Y/0/1/0/all/0/1">Yuchan Wang</a> (Durham), <a href="http://arxiv.org/find/astro-ph/1/au:+Li_B/0/1/0/all/0/1">Baojiu Li</a> (ICC, Durham), <a href="http://arxiv.org/find/astro-ph/1/au:+Cautun_M/0/1/0/all/0/1">Marius Cautun</a> (Leiden)
Observations of galaxy clustering are made in redshift space, which results
in distortions to the underlying isotropic distribution of galaxies. These
redshift-space distortions (RSD) not only degrade important features of the
matter density field, such as the baryonic acoustic oscillation (BAO) peaks,
but also pose challenges for the theoretical modelling of observational probes.
Here we introduce an iterative nonlinear reconstruction algorithm to remove RSD
effects from galaxy clustering measurements, and assess its performance by
using mock galaxy catalogues. The new method is found to be able to recover the
real-space galaxy correlation function, and reduce the quadrupole moment to
zero, with a $sim1%$ accuracy, on scales $sgtrsim15$-$20h^{-1}{rm Mpc}$. It
also leads to an improvement in the reconstruction of the initial density
field, which could help to accurately locate the BAO peaks. An `internal
calibration’ scheme is proposed to determine the values of cosmological
parameters as a part of the reconstruction process, and possibilities to break
parameter degeneracies are discussed. RSD reconstruction can offer a potential
way to simultaneously extract the cosmological parameters, initial density
field, real-space galaxy positions and large-scale peculiar velocity field (of
the real Universe), making it an alternative to standard perturbative
approaches in galaxy clustering analysis, bypassing the need for RSD modelling.
Observations of galaxy clustering are made in redshift space, which results
in distortions to the underlying isotropic distribution of galaxies. These
redshift-space distortions (RSD) not only degrade important features of the
matter density field, such as the baryonic acoustic oscillation (BAO) peaks,
but also pose challenges for the theoretical modelling of observational probes.
Here we introduce an iterative nonlinear reconstruction algorithm to remove RSD
effects from galaxy clustering measurements, and assess its performance by
using mock galaxy catalogues. The new method is found to be able to recover the
real-space galaxy correlation function, and reduce the quadrupole moment to
zero, with a $sim1%$ accuracy, on scales $sgtrsim15$-$20h^{-1}{rm Mpc}$. It
also leads to an improvement in the reconstruction of the initial density
field, which could help to accurately locate the BAO peaks. An `internal
calibration’ scheme is proposed to determine the values of cosmological
parameters as a part of the reconstruction process, and possibilities to break
parameter degeneracies are discussed. RSD reconstruction can offer a potential
way to simultaneously extract the cosmological parameters, initial density
field, real-space galaxy positions and large-scale peculiar velocity field (of
the real Universe), making it an alternative to standard perturbative
approaches in galaxy clustering analysis, bypassing the need for RSD modelling.
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