Local-Group tests of dark-matter concordance cosmology - Towards a new paradigm for structure formation

By Pavel Kroupa, B. Famaey, K. S. Boer, Joerg Dabringhausen, M. Pawlowski, C. Boily, H. Jerjen, D. Forbes, Gerhard Hensler, M. Metz. 2010

234 citations recorded by the source corpus.

Predictions of the concordance cosmological model (CCM) of the structures in the environment of large spiral galaxies are compared with observed properties of Local Group galaxies. Five new, most probably irreconcilable problems are uncovered: 1) A wide variety of published CCM models consistently predict some form of relation between dark-matter-mass and luminosity for the Milky Way (MW) satellite galaxies, but none is observed. 2) The mass function of luminous sub-haloes predicted by the CCM contains too few satellites with dark matter (DM) mass ≈10 7 Mwithin their innermost 300 pc than in the case of the MW satellites. 3) The Local Group galaxies and data from extragalactic surveys indicate there is a correlation between bulge-mass and the number of luminous satellites that is not predicted by the CCM. 4) The 13 new ultra-faint MW satellites define a disc-of-satellites (DoS) that is virtually identical to the DoS previously found for the 11 classical MW satellites, implying that most of the 24 MW satellites are correlated in phase-space. 5) The occurrence of two MW-type DM halo masses hosting MW-like galaxies is unlikely in the CCM. However, the properties of the Local Group galaxies provide information leading to a solution of the above problems. The DoS and bulge-satellite correlation suggest that dissipational events forming bulges are related to the processes forming phase-space correlated satellite populations. These events are well known to occur since in galaxy encounters energy and angular momentum are expelled in the form of tidal tails, which can fragment to form populations of tidal-dwarf galaxies (TDGs) and associated star clusters. If Local Group satellite galaxies are to be interpreted as TDGs then the substructure predictions of the CCM are internally in conflict. All findings thus suggest that the CCM does not account for the Local Group observations and that therefore existing as well as new viable alternatives have to be further explored. These are discussed and natural solutions for the above problems emerge.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/eacb4694cd1ce892531381f21b26386d11e57b41

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Citations in the corpus

The VPOS: a vast polar structure of satellite galaxies, globular clusters and streams around the Milky Way (2012, methodology): “The plot includes the direction of the normal to the DoS derived from 24 satellite galaxies of the MW by Kroupa et al. (2010).”
Dwarf galaxy planes: the discovery of symmetric structures in the Local Group (2013, methodology): “This plane fit reproduces the earlier results of Kroupa et al. (2010) (∆ = 28.9 kpc, DMW = 8.2 kpc, n pointing to (l, b) = (156◦.4,−2◦.2)), even though the current sample includes updated radial distances for some of the satellites, four additional objects (Canis Major, Segue I and II and Bootes…”
HYDRODYNAMICS OF HIGH-REDSHIFT GALAXY COLLISIONS: FROM GAS-RICH DISKS TO DISPERSION-DOMINATED MERGERS AND COMPACT SPHEROIDS (2010, result): “This would lend support to recent suggestions that the rate of TDG formation could be high at high redshift (Kroupa et al. 2010).”
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensions (2011, background): “4) in major mergers, and could then evolve to lead to the population of dwarf ellipticals seen today, thereby providing a natural explanation for the observed density-morphology relation [239] (more dwarf ellipticals in denser environments).”
Families of dynamically hot stellar systems over 10 orders of magnitude in mass (2011, background): “Kroupa et al. (2010) discuss this phenomenon in a cosmological context, and conclude that the combination of high dynamical mass-to-light ratios with a < a0 is natural in a MONDian universe.”
Evidence for top-heavy stellar initial mass functions with increasing density and decreasing metallicity (2012, methodology): “The method used to find p follows the same basic principle as Kroupa et al. (2010) used to determine the orientation of the disc of Milky Way satellites.”
Co-orbiting satellite galaxy structures are still in conflict with the distribution of primordial dwarf galaxies (2014, background): “If additional satellite objects were to be considered, suchas the faint satellite galaxies (Kroupa et al. 2010), globularclusters and stellar and gaseous streams in the MW halo (Pawlowski et al. 2012), the probability to find the observed situation in theseΛCDM simulations would be even smaller.”
The stellar and sub-stellar IMF of simple and composite populations (2011, background): “We have seen above that the IMF is largely insensitive to star-forming conditions as found in the present-day Local Group.”
THE BARYONIC TULLY–FISHER RELATION OF GAS-RICH GALAXIES AS A TEST OF ΛCDM AND MOND (2011, background): “This is hardly the only problem faced by the theory (e.g., Kroupa et al. 2010; Kuzio de Naray & Spekkens 2011; Bovill & Ricotti 2011), so the persistent failure to detect WIMPs is worrisome.”
The current status of galaxy formation (2012, background): “The details of the thickness of this plane remained to be settled (e.g., Kroupa et al., 2010 versus Libeskind et al., 2011).”