Unveiling the Hidden Halos: The New Discovery of Baryonic Matter
Where dark matter resides is one of the greatest mysteries of the cosmos; however, for those who assumed we had located all baryonic matter —the “conventional” matter—in the universe, they were mistaken. Recent findings suggest that a significant quantity of this matter remains hidden from our observational capabilities until now.
The Missing Piece. A recent study has identified the elusive baryonic matter that was previously obscured, constituting nearly half of the universe’s conventional matter, which itself accounts for just about 15% of the universe’s total mass. This groundbreaking discovery leveraged the power of Fast Radio Bursts (FRBs) —mysterious bursts of radio waves that occasionally traverse the cosmos, effectively “illuminating” the baryonic matter within this intergalactic network.
A Network of Cosmic Highways. The cosmic network consists of enormous filaments in the intergalactic space , where a substantial portion of the universe’s matter is dispersed. These filaments are stretched clouds of gas and particles, whose properties are being gradually unraveled by scientists.
Prior studies had documented the existence of this elusive network, but observing it posed challenges due to the inert nature of the gas and particles that lack luminosity. Consequently, detailed observations required several hours of observation time using powerful telescopes, such as the Very Large Telescope (VLT) operated by the European Southern Observatory (ESO).
DSA-110. To carry out this study, researchers constructed their own observatory in the California desert called the Deep Synoptic Array (DSA)-110 . The name refers to a telescope consisting of a network of 110 antennas designed for optimal detection.
FRB. The DSA-110 was instrumental in detecting 39 out of 69 FRBs , which were pivotal for this discovery. These intense and intriguing radio signals from the cosmos remain largely mysterious, with their origins unclear. Researchers speculate that they may be produced by supernovae or similar cosmic events. Some FRBs repeat periodically while others are one-offs; for some, their source can be pinpointed to specific galaxies, while for others, the origin remains elusive.
The FRBs utilized in this research originated from distances ranging from 11.74 million light-years to 9.1 billion light-years , with the latter marked by the event FRB 20230521B, setting a new record as the farthest burst ever detected.
Shedding Light on Highways. According to the research team, the FRBs “shine through the fog of the intergalactic medium .” By studying how the light diminishes upon encountering matter, scientists can measure this obscuring fog.
As the light from the FRBs traverses the filaments, it also separates into different wavelengths, akin to light passing through a prism to form a rainbow. The degree to which the light breaks down provides crucial insights into the medium it permeates.
The study’s findings were published in an article in Nature Astronomy , illustrating the magnitude of this discovery.
Halos or Networks. Previous cosmological models indicated that there was more baryonic matter in the universe than we could observe. The new estimates of the mass of the vast cosmic network filaments allow us to fill in these gaps. The estimates suggest that 76% of conventional matter in the cosmos is found within the intergalactic medium, while 15% is contained in galaxies’ “halos,” with nearly 9% comprising what lies within galaxies themselves: stars, planets, and all terrestrial structures within these vast cosmic entities.
In a world where dark matter remains one of the most fascinating mysteries in physics, this discovery opens a new chapter in our understanding of the universe, offering fresh avenues for research and insights into its intricate fabric.
As we continue to explore these cosmic phenomena, the understanding of baryonic matter may not only reveal more about our own galaxy but could also redefine our comprehension of the universe’s structure and evolution . The quest for knowledge continues, illuminating the paths that lead us to uncover the fabric of the cosmos.
Images: Vikram Ravi/Caltech/OVRO and Jack Madden, IllustrisTNG, Ralf Konietzka, Liam Connor/CfA