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Vasily Belokurov

Dr Vasily Belokurov

Dr Vasily Belokurov

Research Fellow

Interests and expertise (Subject groups)

Grants awarded

Tracing Gravity with Stars. Galactic Structure and Dynamics Revisited.

Scheme: University Research Fellowship

Organisation: University of Cambridge

Dates: Oct 2008-Dec 2013

Value: £443,823.20

Summary: My research is about uncovering the assembly history of our own Galaxy. Using stellar archaeology, I will learn about the shape of the gravitational potential of the Milky Way. Structure formation and dynamics within any galaxy is governed by gravity, but most of the mass in the Universe is in, so-called, dark matter whose distribution is impossible to observe directly. Not only most of the matter is dark, it is also cold - cold in the sense of moving very slowly. According to Big Bang Cosmology, in the early Universe, particles of normal matter could not slow down in time to start forming first stars and galaxies. Cold dark matter (CDM) is required to provide seeds for the ordinary matter to cluster around. However, if without CDM the world is too homogeneous, with CDM it seems too lumpy, at least on the scales smaller than the size of a typical massive galaxy. It was revealed by computer simulations that galaxies like our own should be surrounded by swarms of dark matter clumps. I propose to use stars torn from satellites orbiting the Milky Way to to study the distribution of mass in the Galaxy. Milky Way's gravity can pull out stars from its puny companions. Some of these stars will move a little bit faster and some a little bit slower than the parent body they just left and in millions of years, the dwarf satellite will grow two long tails. One in front, leading the satellite on its orbital motion, and one behind, trailing. If we can find a satellite with tidal tails, we will know everything about its orbit and, therefore, the underlying potential. The longer the stream orbits in the halo of the Galaxy the higher the probability that it would be scattered by passing dark matter clumps. I have discovered a stream ideal for studies of lumpiness of the Milky Way dark matter halo. I will need to measure accurate positions, distances and velocities of hundreds of stars in this stream to figure out how many and how massive dark matter clumps are.

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