Misel Colloquium: Carlos Frenk
The “Lambda cold dark matter'' (LCDM) cosmological model is one of the great achievements in Physics of the past thirty years. Theoretical predictions formulated in the 1980s turned out to agree remarkably well with measurements, performed decades later, of the galaxy distribution and the temperature structure of the cosmic microwave background radiation. Yet, these successes do not inform us directly about the nature of the dark matter. This manifests itself most clearly on subgalactic scales, including the dwarf satellite galaxies of the Milky Way and especially less massive dark matter halos, too small to have made a galaxy. Apparent contradictions between the predictions from cosmological simulations and observations have led to the perception of a “small-scale crisis” for LCDM. I will argue that this perception stems from an inappropriate application of the simulations and that, in fact, the theory is entirely consistent with available data. I will contrast the predictions of LCDM with those of the interesting alternative of warm dark matter and show how forthcoming gravitational lensing and gamma-ray data can conclusively distinguish between the two.