Complementarity of Peculiar Velocity Surveys and Redshift Space Distortions for Testing Gravity. (arXiv:1911.09121v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kim_A/0/1/0/all/0/1">Alex G. Kim</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Linder_E/0/1/0/all/0/1">Eric V. Linder</a>

Peculiar-velocity surveys of the low-redshift universe have significant
leverage to constrain the growth rate of cosmic structure and test gravity.
Wide-field imaging surveys combined with multi-object spectrographs (e.g. ZTF2,
LSST, DESI, 4MOST) can use Type Ia supernovae as informative tracers of the
velocity field, reaching few percent constraints on the growth rate $fsigma_8$
at $zlesssim0.2$ where density tracers cannot do better than $sim10%$.
Combining the high-redshift DESI survey mapping redshift space distortions with
a low-redshift supernova peculiar velocity survey using LSST and DESI can
determine the gravitational growth index to $sigma(gamma)approx0.02$,
testing general relativity. We study the characteristics needed for the
peculiar velocity survey, and how its complementarity with clustering surveys
improves when going from a $Lambda$CDM model assumption to a $w_0$-$w_a$
cosmology.

Peculiar-velocity surveys of the low-redshift universe have significant
leverage to constrain the growth rate of cosmic structure and test gravity.
Wide-field imaging surveys combined with multi-object spectrographs (e.g. ZTF2,
LSST, DESI, 4MOST) can use Type Ia supernovae as informative tracers of the
velocity field, reaching few percent constraints on the growth rate $fsigma_8$
at $zlesssim0.2$ where density tracers cannot do better than $sim10%$.
Combining the high-redshift DESI survey mapping redshift space distortions with
a low-redshift supernova peculiar velocity survey using LSST and DESI can
determine the gravitational growth index to $sigma(gamma)approx0.02$,
testing general relativity. We study the characteristics needed for the
peculiar velocity survey, and how its complementarity with clustering surveys
improves when going from a $Lambda$CDM model assumption to a $w_0$-$w_a$
cosmology.

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