The mass distribution in Spirals

TL;DR

Recent observations of spiral galaxies reveal a universal mass distribution profile combining stellar and dark matter components, with dark halos featuring constant density cores, challenging current $ ext{Lambda}$CDM cosmological models.

Contribution

This paper synthesizes observational data to characterize the universal mass profile in spirals and highlights discrepancies with standard cosmological theories.

Findings

Spiral rotation curves follow a universal profile from centers to virial radii.

Dark halos have a constant density core, contrary to some theoretical predictions.

The importance of dark matter decreases with galaxy mass.

Abstract

In the past years a wealth of observations has unraveled the structural properties of the Dark and Luminous mass distribution in spirals. These have pointed out to an intriguing scenario not easily explained by present theories of galaxy formation. The investigation of individual and coadded objects has shown that the spiral rotation curves follow, from their centers out to their virial radii, a Universal profile (URC) that arises from the tuned combination of a stellar disk and of a dark halo. The importance of the latter component decreases with galaxy mass. Individual objects, on the other hand, have clearly revealed that the dark halos encompassing the luminous discs have a constant density core. This resulting observational scenario poses important challenges to presently favored theoretical $\Lambda$CDM Cosmology.