by Staff Writers Paris (ESA) Nov 23, 2012 Scanning the sky at
microwave and sub-millimetre wavelengths with Planck,
astronomers have unambiguously detected a 'bridge' of hot gas
connecting two galaxy clusters, Abell 399 and Abell 401. The
filament extends over about 10 million light-years and contains
gas with a temperature of about 80 million K. At least part of
this gas might derive from the warm-hot intergalactic medium
(WHIM) - the elusive web of gaseous filaments which is believed
to pervade the Universe. The current understanding of cosmology
suggests that the Universe is dominated by dark matter and dark
energy. The remaining 'normal' matter - or baryonic matter - of
which stars and planets are made, accounts for just a tiny
fraction of the cosmic budget, less than five per cent. Baryonic
matter can, in principle, be detected through the
electromagnetic radiation it releases. But there's a problem:
the amounts of baryonic matter detected via astronomical
observations in the distant, ancient Universe an