ΛCDM and the distribution of dark matter in galaxies: A constant–density halo around DDO 47

Abstract

Abstract. In this paper we present a test case for the existence of a core in the density distribution of dark halos around galaxies. DDO 47 has a rotation curve that increases linearly from the first data point, at 300 pc, up to the last one, at 5 kpc. This profile implies the presence of a (dark) halo with an (approximately) constant density over the region mapped by data. This evidences the inability of standard Λ Cold Dark Matter scenario to account for the dark matter distribution around galaxies, and points toward the existence of an intriguing halo scale-length of homogeneity. This work adds up to the results of Blais-Ouellette et al. (2002) and Bottema (2002) in suggesting that at galactic scales CDM theory should incorporate, as an intrinsic property, a "density core" feature.

High‐Resolution Measurements of the Halos of Four Dark Matter–Dominated Galaxies: Deviations from a Universal Density Profile

“…A number of previous authors have reached similar conclusions (e.g., de Blok et al 2001aBlok et al , 2001bBorriello & Salucci 2001;de Blok & Bosma 2002;Salucci et al 2003;Simon et al 2003). We emphasize, however, that the observation that pseudoisothermal fits produce lower reduced 2 values than NFW or Moore profiles does not demonstrate the presence of a constant-density core.…”

“…Many authors have concluded that density profiles with constant-density cores fit the rotation curves of dwarf and LSB galaxies better than cuspy density profiles do (e.g., de Blok et al 2001aBlok et al , 2001bBorriello & Salucci 2001;de Blok & Bosma 2002;Salucci et al 2003;Simon et al 2003). Typical results from these studies are that the distribution of density profile slopes is ¼ 0:2 AE 0:2 (de Blok et al 2001ade Blok & Bosma 2002).…”

“…The simulations generate dark matter halos with central density cusps of / r À1 or steeper (e.g., Navarro et al 1996, hereafter NFW; Moore et al 1999). Observations of dwarf and low surface brightness ( LSB) galaxies, however, have usually shown that density profiles with shallow central cores, in which the density is nearly constant with radius, fit the data better than cuspy profiles ( Moore 1994;Burkert 1995;Blais-Ouellette et al 1999de Blok et al 2001ade Blok et al , 2001bBorriello & Salucci 2001;de Blok & Bosma 2002;Salucci et al 2003;Weldrake et al 2003;Simon et al 2003;Gentile et al 2004). This disparity is important because density profiles represent some of the strongest available constraints on the CDM simulations at small spatial scales.…”

Analysis of Rotation Curves in the Framework of the Gravitational Suppression Model

“…High-resolution radio observations from spiral galaxies, along with their optical RC's, suggest that the dark matter is distributed in spherical haloes with nearly constant density cores (see [2,3,4] and references therein). On the other hand, theoretical predictions from the well known N-body ΛCDM simulations (e.g.…”

Brief History of Ultra-light Scalar Dark Matter Models

“…While numerical results of the cold dark matter (CDM) model are remarkably successful in explaining the large scale structure of the universe, it encounters some problems at the scale of galactic or sub-galactic structures. For example, the numerical simulations usually predict cusped central halo density and too many sub-halos and small galaxies, which seem to be in contradiction with observations [2][3][4][5].Recently, there is a growing interest in the idea that DM particles are ultra-light scalars in Bose-Einstein condensate (BEC). (For a review, see Refs.…”