The Intriguing Distribution of Dark Matter in Galaxies

Abstract

Abstract. We review the most recent evidence for the amazing properties of the density distribution of the dark matter around spiral galaxies. Their rotation curves, coadded according to the galaxy luminosity, conform to an Universal profile which can be represented as the sum of an exponential thin disk term plus a spherical halo term with a flat density core. From dwarfs to giants, these halos feature a constant density region of size r0 and core density ρ0 related by ρ0 = 4.5 × 10 −2 (r0/kpc) −2/3 M⊙pc −3 . At the highest masses ρ0 decreases exponentially with r0, revealing a lack of objects with disk masses > 10 11 M⊙ and central densities > 1.5 × 10 −2 (r0/kpc) −3 M⊙pc −3 implying a maximum mass of ≈ 2 × 10 12 M⊙ for a dark halo hosting a stellar disk. The fine structure of dark matter halos is obtained from the kinematics of a number of suitable low-luminosity disk galaxies. The halo circular velocity increases linearly with radius out to the edge of the stellar disk, implying a constant dark halo density over the entire disk region. The properties of halos around normal spirals provide substantial evidence of a discrepancy between the mass distributions predicted in the Cold Dark Matter scenario and those actually detected around galaxies.

Dark Matter Search Results from the CDMS II Experiment

“…Weakly Interacting Massive Particles (WIMPs) [2] are a class of candidates for this dark matter which are particularly well motivated by proposed extensions to the Standard Model of particle physics and by thermal production models for dark matter in the early universe [3,4,5,6]. WIMPs, distributed in a halo surrounding our galaxy, would coherently scatter off nuclei in terrestrial detectors [7,8,9] with a mean recoil energy of ∼ tens of keV, presently limited by observation to a rate of less than 0.1 event 5,6,10]. Direct search experiments seek recoil signatures of these interactions and have achieved the sensitivity to begin testing the most interesting classes of WIMP models [11,12,13,14].…”

Binary black hole mergers inf(R)theory

“…We simulate the development of the scalar field from the ground state of the Schrödinger-Newton system considered in [45]. Other authors model the dark matter halo [46] in the center of a galaxy with a similar profile (see e.g., [47]). Our result shows that the scalar field evolves from the ground state configuration to a shell-type profile (similar to (44)).…”

Limits on Spin-Independent Interactions of Weakly Interacting Massive Particles with Nucleons from the Two-Tower Run of the Cryogenic Dark Matter Search

“…The combined limit from Ge (Si) is a factor of 2.5 (10) lower than our previous results and constrains predictions of supersymmetric models. One-quarter of the energy density of the universe consists of nonbaryonic dark matter [1], which is gravitationally clustered in halos surrounding visible galaxies [2]. The weakly interacting massive particle (WIMP) [3], a dark matter candidate, arises independently from considerations of big bang cosmology and from supersymmetric phenomenology, where the neutralino can be a WIMP [4,5].…”