Diffuse puffs of “missing” matter surround most galaxies

For decades, physicists have known that the amount of ordinary matter in the universe does not match early predictions. A significant portion of this matter remains hidden from view. Now, researchers at MIT have tracked down this missing material by analyzing signals from fast radio bursts. These bursts are intense flashes of radio waves that occur in the deep universe. As they travel toward Earth, they encounter matter that causes the signal to smear in time. By measuring this distortion, scientists can determine exactly how much material the signal passed through on its way here.

Working with the CHIME/FRB Collaboration, the team compared thousands of these radio signals with the known locations of millions of galaxies. This data indicates that the missing matter is not evenly distributed. Instead, it exists in diffuse, sprawling clouds surrounding galaxy groups. These clouds extend far beyond the galaxies themselves, reaching distances of up to 4 million light years.

These findings change our understanding of how galaxies behave. The data suggests that galaxies function like fountains. Energetic processes, such as black hole jets and star explosions, launch gas and other baryonic matter deep into the surrounding space. This activity appears far more violent and powerful than previous models predicted.

Mapping this matter provides a new way to observe how galaxies form and interact with their environments. The research confirms that fast radio bursts serve as a precise tool for cosmic exploration. As more radio signals are detected, the researchers expect their maps of this hidden matter to become increasingly detailed. This work marks a shift in how we study the structure of the universe, moving from theoretical models to direct observation of these distant gas clouds.