The two main characteristics of Dark Matter are its puzzling ubiquity and its omnipotent evasiveness. To create galaxies, stars and planets, we need Cold Dark Matter to enhance minuscule primordial density fluctuations and provide seeds for the ordinary matter to cluster around. However, in the last 30 years, the colossal international efforts to detect this alien substance have made little progress. Yet there is one strong and imminently testable prediction of the modern Cosmology: in the early Universe, Dark Matter starts collapsing first and ends up arranging itself into a hierarchy of invisible clumps of all sizes. Detecting these dark haloes through their gravitational effects is feasible with existing technology and quantifying their abundance will shed light on the nature of Dark Matter.
The objective of this Proposal is to study the evolution of the stellar phase-space density in the nearby tidal streams to quantify the abundance of the dark matter clumps in the Galactic halo. To probe the granularity of the Milky Way gravitational potential we will discover, measure and identify progenitors of, new Milky Way stellar tidal streams, both using the data from all-sky imaging and spectroscopic surveys and by conducting our own observational campaign. To link the amplitude and the amount of streams' perturbations to the sub- halo mass function, we will develop models of streams’ orbital evolution and will investigate the process of stellar debris scattering with N-body simulations. The ultimate judgement as to the lumpiness of the dark matter locally will come from application of the techniques developed in this project to the revolutionary datasets of Gaia and LSST.
Fields of science
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