Detection and analysis of cluster-cluster filaments. (arXiv:1911.06768v2 [astro-ph.CO] UPDATED)

<a href="http://arxiv.org/find/astro-ph/1/au:+Pereyra_L/0/1/0/all/0/1">Luis A. Pereyra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sgro_M/0/1/0/all/0/1">Mario A. Sgró</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Merchan_M/0/1/0/all/0/1">Manuel E. Merchán</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stasyszyn_F/0/1/0/all/0/1">Federico A. Stasyszyn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paz_D/0/1/0/all/0/1">Dante J. Paz</a>

In this work, we identify and analyse the properties of cluster-cluster

filaments within a cosmological simulation assuming that they are structures

connecting maxima of the density field defined by dark matter halos with masses

$M , ge 10^{14}, h^{-1} mathrm{M_{odot}}$. To extract these filaments we

develop an identification algorithm based on two standard tools: the Minimal

Spanning Tree (MST) and the Friends of Friends (FoF) algorithm. Focusing our

analysis on the densest dark matter filaments, we found that the radial density

profile, at scales around $1, h^{-1} mathrm{Mpc}$, approximately follow a

power-law function with index -2. Without making any assumption about the

velocity field, our algorithm finds that the saddle point arises as a natural

characteristic of the filamentary structure. In addition, its location along

the filament depends on the masses of the halos at the filament ends. We also

found that the infall velocities follow a cross-pattern near the saddle point,

being perpendicular to the filament spine when approaching from low-density

regions, and parallel away from the saddle point towards the ends of the

filament. Following theoretical prescriptions, we estimate the linear density

from the transverse velocity dispersion, finding a good correspondence with the

measured mass per unit length of our filaments. Our results can be applied to

observational samples of filaments in order to link the saddle point location

and the mass per unit length with measurements obtained from observations such

as cluster masses and the velocity dispersion of galaxies.

In this work, we identify and analyse the properties of cluster-cluster

filaments within a cosmological simulation assuming that they are structures

connecting maxima of the density field defined by dark matter halos with masses

$M , ge 10^{14}, h^{-1} mathrm{M_{odot}}$. To extract these filaments we

develop an identification algorithm based on two standard tools: the Minimal

Spanning Tree (MST) and the Friends of Friends (FoF) algorithm. Focusing our

analysis on the densest dark matter filaments, we found that the radial density

profile, at scales around $1, h^{-1} mathrm{Mpc}$, approximately follow a

power-law function with index -2. Without making any assumption about the

velocity field, our algorithm finds that the saddle point arises as a natural

characteristic of the filamentary structure. In addition, its location along

the filament depends on the masses of the halos at the filament ends. We also

found that the infall velocities follow a cross-pattern near the saddle point,

being perpendicular to the filament spine when approaching from low-density

regions, and parallel away from the saddle point towards the ends of the

filament. Following theoretical prescriptions, we estimate the linear density

from the transverse velocity dispersion, finding a good correspondence with the

measured mass per unit length of our filaments. Our results can be applied to

observational samples of filaments in order to link the saddle point location

and the mass per unit length with measurements obtained from observations such

as cluster masses and the velocity dispersion of galaxies.

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