Astronomers have made a perplexing discovery that’s pushing the boundaries of what we know about mysterious cosmic signals. Using specialized telescopes, they’ve detected powerful radio bursts coming from an unexpected location: the distant outskirts of an ancient, inactive galaxy located 2 billion light-years from Earth.
The discovery began when researchers using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) telescope detected repeated bursts of intense radio waves from a source in the northern constellation Ursa Minor. These cosmic signals, known as fast radio bursts (FRBs), appear as powerful flashes that last for just milliseconds.
Between February and July 2024, the team observed 22 separate bursts from this single source, dubbed “FRB 20240209A.” To precisely locate these signals, they combined observations from CHIME with those from a partner facility called KKO, located 66 kilometers away. This combination worked like a giant pair of astronomical binoculars, allowing unprecedented precision in pinpointing the bursts’ origin.
What they found challenged existing theories: the signals were coming from approximately 40,000 light-years away from the center of their host galaxy –roughly twice the distance from Earth to the center of our Milky Way. This represents the largest offset from a host galaxy ever observed for an FRB source.
Even more puzzling was the nature of the host galaxy itself. Unlike most galaxies where these signals have been found before, this one is an elliptical galaxy estimated to be 11.3 billion years old, which is quite ancient by cosmic standards. With a mass more than 100 billion times that of our Sun, this galaxy is effectively “dead,” meaning new stars rarely form there.
“This is not only the first FRB to be found outside a dead galaxy, but compared to all other FRBs, it’s also the farthest from the galaxy it’s associated with,” said Vishwangi Shah, a doctoral student at McGill University and lead author of the study, in a statement. “The FRB’s location is surprising and raises questions about how such energetic events can occur in regions where no new stars are forming.”
The discovery, described in The Astrophysical Journal Letters, challenges the leading theory that these bursts come from magnetars, which are highly magnetized, spinning neutron stars left over from the explosive deaths of massive young stars. In an galaxy as old as this one, such stellar remnants should have disappeared long ago.
One possible explanation is that the bursts might be coming from a globular cluster — a dense collection of ancient stars that orbits the main galaxy. “The source could be in a globular cluster, a dense region of old, dead stars outside the galaxy. If confirmed, it would make FRB 20240209A only the second FRB linked to a globular cluster,” Shah noted.
To investigate further, the research team used the Gemini North telescope in Hawaii to study this region in detail. While they were looking for signs of a small companion galaxy that might be hosting these bursts, they found nothing visible at that location, deepening the mystery.
The timing pattern of these signals provides additional intrigue. After its initial discovery in February 2024, the source remained relatively quiet for several months before dramatically increasing its activity in June, producing 17 bursts in just one month.
It’s been an exciting time for fast radio burst research. A third telescope array is being added to the CHIME network at Hat Creek Observatory in Northern California, which will help scientists locate these mysterious bursts with even greater precision. “When paired with the three outriggers, we should be able to accurately pinpoint one FRB a day to its galaxy, which is substantial,” said Calvin Leung, a Miller Postdoctoral Fellow at UC Berkeley and co-author of the study.
This discovery expands our understanding of where these enigmatic signals can occur and what might be producing them. Finding repeating bursts in such an unexpected location suggests multiple formation pathways for these cosmic phenomena, providing new directions for future research.
Source : https://studyfinds.org/dead-galaxy-fast-radio-bursts/
