Cold Dark Matter
New Scientist 2017 11 October
Hideki Tanimura at the Institute of Space Astrophysics in Orsay, France
Anna de Graaff at the University of Edinburgh, UK.
There may be no exotic dark matter, just gas that is very difficult to detect without large, sensitive instruments in space. Planck can only image some of this "dim" matter by overlaying hundreds of images, which cannot detect other baryons (mostly protons) that are not clustered this way.