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Research Fellows Directory

Vasily Belokurov

Dr Vasily Belokurov

Research Fellow


University of Cambridge

Research 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


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.

Grants awarded

Tracing Gravity with Stars. Galactic Structure and Dynamics Revisited.

Scheme: University Research Fellowship

Dates: Oct 2008 - Dec 2013

Value: £443,823.20