Density and velocity profiles around cosmic voids. (arXiv:1811.03132v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Massara_E/0/1/0/all/0/1">Elena Massara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sheth_R/0/1/0/all/0/1">Ravi K. Sheth</a>
We study the evolution of the cross-correlation between voids and the mass
density field – i.e. of void profiles. We show that approaches based on the
spherical model alone miss an important contribution to the evolution on large
scales of most interest to cosmology: they fail to capture the well-known fact
that the large-scale bias factor of conserved tracers evolves. We also show
that the operations of evolution and averaging do not commute, but this
difference is only significant within about two effective radii. We show how to
include a term which accounts for the evolution of bias, which is directly
related to the fact that voids move. The void motions are approximately
independent of void size, so they are more significant for smaller voids that
are typically more numerous. This term also contributes to void-matter pairwise
velocities: including it is necessary for modeling the typical outflow speeds
around voids. It is, therefore, important for void redshift space distortions.
Finally, we show that the excursion set peaks/troughs approach provides a
useful, but not perfect framework for describing void profiles and their
evolution.
We study the evolution of the cross-correlation between voids and the mass
density field – i.e. of void profiles. We show that approaches based on the
spherical model alone miss an important contribution to the evolution on large
scales of most interest to cosmology: they fail to capture the well-known fact
that the large-scale bias factor of conserved tracers evolves. We also show
that the operations of evolution and averaging do not commute, but this
difference is only significant within about two effective radii. We show how to
include a term which accounts for the evolution of bias, which is directly
related to the fact that voids move. The void motions are approximately
independent of void size, so they are more significant for smaller voids that
are typically more numerous. This term also contributes to void-matter pairwise
velocities: including it is necessary for modeling the typical outflow speeds
around voids. It is, therefore, important for void redshift space distortions.
Finally, we show that the excursion set peaks/troughs approach provides a
useful, but not perfect framework for describing void profiles and their
evolution.
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