Cold dark matter heats up
  One of the principal discoveries in modern cosmology is that standard model
particles (including baryons, leptons and photons) together comprise only 5% of
the mass-energy budget of the Universe. The remaining 95% consists of dark
energy and dark matter (DM). Consequently our picture of the universe is known
as {\Lambda}CDM, with {\Lambda} denoting dark energy and CDM cold dark matter.
{\Lambda}CDM is being challenged by its apparent inability to explain the low
density of DM measured at the centre of cosmological systems, ranging from
faint dwarf galaxies to massive clusters containing tens of galaxies the size
of the Milky Way. But before making conclusions one should carefully include
the effect of gas and stars, which were historically seen as merely a passive
component during the assembly of galaxies. We now understand that these can in
fact significantly alter the DM component, through a coupling based on rapid
gravitational potential fluctuations.
