Dark Matter in Galaxies: evidences and challenges

Abstract

The evidence of the phenomenon for which, in galaxies, the gravitating mass is distributed differently than the luminous mass, increases as new data become available. Furthermore, this discrepancy is well structured and it depends on the magnitude and the compactness of the galaxy and on the radius, in units of its luminous size $R_{opt}$, where the measurement is performed. For the disk systems with $-13\ge M_I\ge -24$ all this leads to an amazing scenario, revealed by the investigation of individual and coadded rotation curves, according to which, the circular velocity follows, from their centers out to their virial radii, an universal profile $V_{URC}(r/R_{opt},M_I)$ function only of the properties of the luminous mass component. Moreover, from the Universal Rotation Curve, so as from many individual high-quality RCs, we discover that, in the innermost regions of galaxies, the DM halo density profiles are very shallow. Finally, the disk mass, the central halo density and its core radius, come out all related to each other and to two properties of the distribution of light in galaxies: the luminosity and the compactness. This phenomenology, being absent in the simplest $\Lambda CDM$ Cosmology scenario, poses serious challenges to the latter or, alternatively, it requires a substantial and tuned involvement of baryons in the formation of the galactic halos. On the other side, the URC helps to explain the two-accelerations relationship found by McGaugh et al 2016, in terms of only well known astrophysical processes, acting in a standard DM halos + luminous disks scenario

21 pages, 16 Figures. Based on an invited review at the Lemaitre Workshop (9-12 May 2017, Vatican Observatory). To appear on Foundation of Physics, 2018. Comments welcome

References in corpus (7)

• The Radial Acceleration Relation in Rotationally Supported Galaxies
• The Universal Rotation Curve of Spiral Galaxies. II The Dark Matter Distribution out to the Virial Radius
• GHASP : an H alpha kinematic survey of spiral and irregular galaxies. V. Dark matter distribution in 36 nearby spiral galaxies
• The universal rotation curve of dwarf disk galaxies
• The Mass-Discrepancy Acceleration Relation: a Natural Outcome of Galaxy Formation in Cold Dark Matter halos
• Λ CDM is Consistent with SPARC Radial Acceleration Relation
• The Radial Tully-Fisher relation for spiral galaxies I

Cited by in corpus (18)

• The Radial Acceleration Relation (RAR): the crucial cases of Dwarf Discs and of Low Surface Brightness galaxies
• Observational constraints on Yukawa cosmology and connection with black hole shadows
• Direct Detection of Dark Matter -- APPEC Committee Report
• Galactic dynamics and long-range quantum gravity
• Dark matter signatures of black holes with Yukawa potential
• Galaxy rotation curves and universal scaling relations: comparison between phenomenological and fermionic dark matter profiles
• Dark Stars Powered by Self-Interacting Dark Matter
• Phase space analysis of the bouncing universe with stringy effects
• Charged Black Holes with Yukawa Potential
• Is a Bose-Einstein Condensate a good candidate for Dark Matter? A test with Galaxy Rotation Curves
• There is no universal acceleration scale in galaxies
• Covariant formulation of refracted gravity
• The proper motion of stars in dwarf galaxies: distinguishing central density cusps from cores
• A low-threshold diamond cryogenic detector for sub-GeV Dark Matter searches
• Bi-metric Universe with Matter
• Frozen-in fermionic singlet dark matter in non-standard cosmology with a decaying fluid
• Dark Matter in a bi-metric universe
• On the radial acceleration of disk galaxies