The Halo Spin Transition as a Probe of Dark Energy

TL;DR

This study demonstrates that the mass-dependent transition of halo spin orientations can distinguish different dark energy models, with the transition zone's width varying with redshift, environment, and smoothing scale, reflecting the underlying cosmology.

Contribution

It provides numerical evidence that the halo spin transition zone can serve as a robust probe to differentiate dark energy models based on their influence on tidal field evolution.

Findings

Differences in the spin transition zone width are significant among dark energy models.

The transition zone becomes narrower at higher redshifts and in filamentary environments.

The transition zone's width is sensitive to the nonlinear evolution of the tidal field.

Abstract

We present a numerical evidence supporting the claim that the mass-dependent transitions of the halo spin orientations from the intermediate to the minor principal directions of the local tidal fields can in principle be a useful discriminator of dark energy models. We first define a spin transition zone as the mass range of the halos, $\Delta m_{t}$, for which the intrinsic spin alignments with the minor tidal principal directions become as strong as that with the intermediate principal directions. Then, utilizing the halo samples from the DEUS simulations performed separately for the WMAP7 $\Lambda$CDM, phantom DE and quintessence models, we investigate if and how the three different dark energy models differ in $\Delta m_{t}$. It is shown that the differences in $\Delta m_{t}$ among the three dark energy models are significant enough to discriminate the models from one another and robust against the variations of the smoothing scale of the tidal field and redshift. Noting that a narrower spin transition zone is more powerful as a probe of dark energy, we also show that the spin transition zones become narrower at higher redshifts, in the filamentary environments and for the case that the tidal fields are smoothed on the smaller scales. Our result is consistent with the scenario that $\Delta m_{t}$ is mainly determined by how fast the nonlinear evolution of the tidal field proceeds, which in turn sensitively depends on the background cosmology.