The universe is mostly made up of dark matter, which is invisible and can only be detected through its gravitational effects. Ordinary matter, on the other hand, makes up only 16 percent of the universe’s mass-energy density. This ordinary matter is spread out across galaxy halos and intergalactic space, making up roughly half of it “missing” until now.
A team of astronomers at Caltech and Harvard & Smithsonian has made a groundbreaking discovery using fast radio bursts (FRBs) to detect and account for all the missing ordinary matter in the universe. The study used brief, bright radio flashes to illuminate the matter between FRBs and Earth, allowing researchers to weigh the foggy intergalactic medium.
The team analyzed 69 FRBs at distances ranging from about 11 million to 9.1 billion light-years away. They found that 76 percent of ordinary matter lies in the space between galaxies, while 15 percent resides in galaxy halos. The remaining 9 percent is concentrated within galaxies.
This discovery aligns with predictions from advanced cosmological simulations but has never been observationally confirmed before. The findings will help researchers better understand how galaxies grow and demonstrate the potential of FRBs in solving problems in cosmology.
The study’s lead author, Liam Connor, notes that this is just the beginning of using FRBs in cosmology, as a new radio telescope currently in planning stages will be able to detect up to 10,000 FRBs per year. This enhanced capability will further deepen our knowledge of normal matter and extreme blasts.
Source: https://www.caltech.edu/about/news/missing-matter-in-universe-found