English

Evolution of mass and velocity filed in comic web: comparison between baryonic and dark matter

Cosmology and Nongalactic Astrophysics 2017-09-05 v1

Abstract

We investigate the evolution of cosmic web since z=5z=5 in grid based cosmological hydrodynamical simulations, focusing on the mass and velocity field of both baryonic and cold dark matter. The tidal tensor of density is used as the main method for web identification, with λth=0.21.2\lambda_{th}=0.2-1.2. The evolution trends in baryonic and dark matter are similar, while moderate differences are observed. Sheets appeared early and their large scale pattern may have been set up by z=3z=3. In term of mass, filaments superseded sheets as the primary collapsing structures at z23z\sim2-3. Tenuous filaments assembled with each other to form prominent ones at z< 2z<~2. In accordance with the construction of the frame of sheets, the cosmic divergence velocity, vdivv_{div}, had been well developed above 2-3 Mpc by z=3. Afterwards, curl velocity, vcurlv_{curl}, grown dramatically along with the rising of filaments, become comparable to vdivv_{div}, for <23Mpc<2-3 Mpc at z=0z=0. The scaling of vcurlv_{curl} can be described by the hierarchical turbulence model. The alignment between vorticity and eigenvectors of shear tensor in baryonic matter field resembles dark matter, and is even moderately stronger between ω\vec{\omega} and e1\vec{e}_1, and e3\vec{e}_3. Compared with dark matter, mildly less baryonic matter is found residing in filaments and clusters, and its vorticity has been developed more significantly below 23Mpc2-3 Mpc. These differences may be underestimated due to the limited resolution and lack of star formation in our simulation. The impact of the change of dominant structures in over-dense regions at z23z\sim2-3 on galaxy formation and evolution is shortly discussed.

Keywords

Cite

@article{arxiv.1702.06768,
  title  = {Evolution of mass and velocity filed in comic web: comparison between baryonic and dark matter},
  author = {Weishan Zhu and Long-Long Feng},
  journal= {arXiv preprint arXiv:1702.06768},
  year   = {2017}
}

Comments

28pages, 24 figures, accepted for publication in The Astrophysical Journal