Scientists have long assumed that about 40 percent of the universe’s ordinary matter – the stuff that makes up everything you can see and touch – was lost, never detected. Now a team from the National Center for Scientific Research (CNRS), France, claims to have finally found it.
The research, published this Friday in the journal Astronomy & Astrophysics and based on data dating back up to 20 years, it has revealed that this matter had been hiding in the giant, fuzzy filaments that connect galaxies.
These gas filaments form an intricate cosmic web that stretches across vast intergalactic voids. According to the CNRS, they sometimes also serve as a source of new matter. The researchers suggest that this would be the reason why the filaments of the network are so diffuse and frayed, with weak signals; so much so that they have gone unnoticed for two decades, even though the data was at our fingertips.
A new look
To find 40 percent of all visible matter in the universe that contains it, the scientists took a new look at the X-ray emissions in 15,000 filament arrangements identified in the SDSS3 galactic survey. Through statistical analysis, the team was able to confirm that the filaments contained large amounts of hot gases previously ignored.
“These are the lost baryons, hidden in the filamentary structure of the cosmic web,” explained Nabila Aghanim, a researcher at the Institut d’Astrophysique Spatiale.
The present finding confirms previous analyzes by the same research team, based on the indirect detection of hot gas in the network through its effect on the cosmic microwave background. It also paves the way for more detailed studies, using better quality data, on the evolution of these filaments and the structures they form.
