Surface density of dark matter haloes on galactic and cluster scales

Abstract

In this paper, in the framework of the secondary infall model, the correlation between the central surface density and the halo core radius of galaxy, and cluster of galaxies, dark matter haloes was analyzed, this having recently been studied on a wide range of scales. We used Del Popolo (2009) secondary infall model taking into account ordered and random angular momentum, dynamical friction, and dark matter (DM) adiabatic contraction to calculate the density profile of haloes, and then these profiles are used to determine the surface density of DM haloes. The main result is that r * (the halo characteristic radius) is not an universal quantity as claimed by Donato et al. (2009) and Gentile et al. (2009). On the contrary, we find a correlation with the halo mass M 200 in agreement with Cardone & Tortora (2010), Boyarsky at al. (2009) and Napolitano et al. ( 2010), but with a significantly smaller scatter, namely 0.16 ± 0.05. We also consider the baryon column density finding this latter being indeed a constant for low mass systems such as dwarfs, but correlating with mass with a slope α = 0.18 ± 0.05. In the case of the surface density of dark matter for a system composed only of dark matter, as in dissipationless simulations, we get α = 0.20 ± 0.05. These results leave little room for the recently claimed universality of (dark and stellar) column density.

The Baryonic Self Similarity of Dark Matter

“…As a result, we would still have a baryonic induced self similarity for each galaxy, but the similarity parameter (the constant in Equation (4)), which is an acceleration would depend on the galaxy type. Interestingly, Del Popolo et al (2013) found that the acceleration constant estimated by Gentile et al (2009) is correlated to the mass of the galaxy, which would support the fact that the scaling in Equation (3) depends on galaxy type. A direct consequence of this finding is also to support the fact that the nearly universal relations observed for galaxies are due to internal physics within the galaxies, a category to which the baryonic feedback obviously belongs.…”

Analytic expressions for the dark matter-baryon relations

“…This result agrees with empirical observations. 22 For a BDG, the typical value of M dt ∼ 10 13 M ⊙ 23 gives g d0 ≈ 4 × 10 −10 m/s 2 . Since ρ s r s depends on M dt slowly, the actual range of g d0 is very small.…”

Energy transfer from baryons to dark matter as a unified solution to small-scale structure issues of the ΛCDM model

“…Here we recall the model used above. First introduced by [17,18], many of its features were developed in [19][20][21], and allowed studies of the density profiles' universality [22,23], of the density profile of galaxies [24][25][26] and clusters [25,27], and of the inner surface-density of galaxies [28].…”