Satellites of the Milky Way
Gabriel Torrealba1*
1IAA, ASIAA, Taipei, Taiwan
* Presenter:Gabriel Torrealba,
The standard model of cosmology states that the dark matter present in the
Universe consists of particles that mainly interact gravitationally. This
model is extremely successful in explaining the large scale structure: from
the Cosmic Microwave Background to how galaxies distribute in the Universe.

In this scenario, the formation of structure, which is dominated by dark matter,
is hierarchical: small structure form first, and then acts as
building blocks to form bigger structure. One of the key predictions of this
scenario, or any scenario where formation of structure is hierarchical, is the
presence of hundreds to thousands of small dark matter halos orbiting galaxies
like the Milky Way. However, due to their dark nature and small scales, these
have proven difficult to find. Nevertheless, while most of the smallest of the
dark halos will remain dark forever, some will be lit by small and dim
galaxies, providing a window of opportunity to probe the nature of dark matter
and the formation of structure at the smallest scales.

In this contribution, I will present some results of a new quest for the
search of the dark halos around the Milky Way, via the detection of small
satellite galaxies. By improving the detection algorithms and by the use of
new deep wide surveys, I have pushed the detection limits yielding several new
discoveries, including the discovery of the enigmatic galaxy Crater 2. Even
when being the fourth largest in the vicinity of the Milky Way, Crater 2
remained hidden until very recently due to its extreme properties. These same
properties may be in tension with our current models of the Universe posing
interesting new challenges to the standard model of cosmology.

Keywords: Dark Matter, Milky Way, Ultra faint dwarf galaxies