December 3, 2015

The cosmic web: seeing what makes up the Universe

An international team observe ordinary matter in the large-scale structures that form the "cosmic web"

Matter known as ordinary, which makes up everything we know, corresponds to only 5% of the Universe. Approximately half of this percentage still eluded detection.

Numerical simulations made it possible to predict that the rest of this ordinary matter should be located in the large-scale structures that form the "cosmic web" at temperatures between 100,000 and 10 million degrees.

An intenational team among which the LAM (Laboratoire d'Astrophysique de Marseille) and the CRAL (Centre de Recherche Astrophysique de Lyon) observed this phenomenon directly. The research shows that the majority of the missing ordinary matter is found in the form of a very hot gas associated with intergalactic filaments.

Credits: ESA/XMM-Newton (X-rays) ; ESO/WFI (optical) ; NASA/ESA & CFHT (dark matter)

The astrophysists pointed a massive heap of galaxies called Abel 2744, they actually found this ordinary material  in the form of very hot gas in cosmic filaments. These results are published in Nature of December 3rd.


D. Eckert et al., Warm-hot baryons comprise 5–10 per cent of filaments in the cosmic web, Nature, 3 December 2015


  • LAM/PYTHEAS scientific contact: Eric Jullo at
  • CNES Astrophysics program scientist: Olivier.LaMarle at