Astronomers have traced a record-breaking fast radio burst originating from a dwarf galaxy when the universe was three billion years old, more than doubling the previous distance record. Detected by the MeerKAT telescope and imaged by the James Webb Space Telescope, the millisecond-long signal traversed around 80 percent of cosmic history before reaching Earth.
FRB 20240304B Crosses Ten Billion Years of Space to Reach Earth
Making a journey through space lasting in excess of 10 billion years to arrive at Earth, a momentary burst of radio waves traveled through space for more than 10 billion years to establish a fresh distance benchmark for a verified fast radio burst.
Fast radio bursts, or FRBs, last only a few thousandths of a second yet release enormous amounts of energy.
Scientists spotted the first one in 2007, and they still don’t know what causes them. Some experts have suggested they may be from an extraterrestrial lifeform trying to contact Earth, but the exact cause and origins of FRBs have remained unconfirmed. Ever since the initial detection, researchers have identified thousands of FRBs originating from sources positioned anywhere from inside our own galaxy to distances spanning billions of light-years.
South Africa’s MeerKAT radio telescope caught the signal, designated FRB 20240304B, on March 4, 2024, using the MeerTRAP system designed to spot transient radio events. Because ground-based telescopes could not locate any galaxy at the precise coordinates, the research team turned to NASA’s James Webb Space Telescope to capture the faint host. Some of the data presented herein were obtained at Keck Observatory.
James Webb Space Telescope Finds an Unexpected Dwarf Galaxy Host
Observations from the Webb telescope’s NIRCam instrument measured the galaxy’s redshift at 2.148. This figure corresponds to an era just three billion years after the Big Bang, when the universe was approximately one-fifth of its current age and running through the peak of star formation known as cosmic noon.
The host galaxy itself surprised astronomers. While most localized bursts inhabit large galaxies, this signal emerged from a metal-poor dwarf system containing roughly 10 million times the mass of the Sun—about 1,000 times less mass than anticipated. The discovery was led by Manisha Caleb and Themiya Nanayakkara from the University of Sydney in Australia, along with co-authors including Dr. Laura Driessen and Kavya Shaji.
“We thought it would be a big, nicely formed galaxy with lots of stars, and instead it was a little dwarf galaxy, although it was actively forming stars.”
Manisha Caleb, University of Sydney
The galaxy was observed during cosmic noon, and most of its stars may have formed within just 30 million years.
Magnetar Starquakes and Intervening Cosmic Structures Revealed Along the Path
The extreme youth and active star formation of the host galaxy help researchers narrow down what generates these flashes. Binary neutron star mergers take billions of years of orbital decay, making them an unlikely source inside such young dwarf systems. Instead, the data favors young magnetars—highly magnetized neutron stars created during supernovas that can produce high-energy bursts through crust-fracturing starquakes.
Beyond locating the origin, the signal acted as a probe of the space between the galaxy and Earth. As the radio waves crossed the cosmos, they gathered dispersion from intervening matter, including a previously unknown galaxy cluster situated roughly 3.5 billion light-years away and the nearby Virgo Cluster.
“A fast radio burst is almost like a cosmic flashlight. It lights up everything along the path.”
J. Xavier Prochaska, University of California, Santa Cruz
By analyzing these signals, researchers can better understand the distribution of matter and the structure of the universe between the source and our own galaxy, more than doubling the previous distance record set before the MeerKAT telescope and the James Webb Space Telescope spotted FRB 20240304B.