By I. Hansana, Jadetimes News
Astronomers Uncover the Source of Cosmic Radio Bursts
In a remarkable stroke of luck, astronomers have solved a long standing cosmic mystery: the origin of powerful, fleeting radio bursts that travel through the universe at incredible speeds. Known as fast radio bursts (FRBs), these energetic pulses have baffled scientists since they were first detected about 13 years ago, primarily because they originate from outside our galaxy, making them difficult to trace.
These radio bursts are exceptionally brief, lasting just a few milliseconds, adding to the challenge of identifying their source. However, in April, a rare and considerably weaker burst was detected coming from within our own Milky Way galaxy. This FRB was captured by two vastly different telescopes: one, a set of handmade antennas built by a California doctoral student, and the other, a $20 million Canadian observatory.
The teams traced this fast radio burst to a magnetar, a peculiar type of neutron star located 32,000 light years from Earth, as detailed in four studies published in the journal Nature. This marks the first time an FRB has been traced to its source and the first time such a burst has been observed within our galaxy. While astronomers believe there could be other sources for these bursts, they are now certain that magnetars are a key player.
Magnetars are incredibly dense neutron stars, with a mass 1.5 times that of our Sun compressed into a space the size of Manhattan. They possess immense magnetic fields that crackle with energy, occasionally releasing flares of X rays and radio waves. According to McGill University astrophysicist Ziggy Pleunis, co author of the Canadian study, the magnetic field surrounding these magnetars is so intense that it can tear apart nearby atoms, revealing strange aspects of fundamental physics.
Astronomer Casey Law of the California Institute of Technology, who was not involved in the research, explained that the extreme conditions around these magnetars make them a rare phenomenon in our galaxy, with only a dozen or so known to exist. This scarcity is attributed to the fact that magnetars are relatively young stars, and the Milky Way is not as active in star formation as other galaxies.
The burst detected in April was incredibly powerful, releasing as much energy in less than a second as our Sun produces in a month. Despite this, it was still far weaker than the FRBs detected from outside our galaxy, according to Caltech radio astronomer Christopher Bochenek, who helped identify the burst using his handmade antennas.
These radio bursts pose no danger to Earth, even the more powerful ones from beyond our galaxy, according to astronomers. The bursts from outside the Milky Way, which travel millions or billions of light-years, are "tens of thousands to millions of times more powerful than anything we have detected in our galaxy," noted Daniele Michilli, an astrophysicist at McGill and a co author of the Canadian study.
FRBs are believed to occur frequently, potentially more than 1,000 times a day outside our galaxy. However, capturing them is a challenge, as it requires being in the right place at the right time, Cornell University's Shami Chatterjee explained.
While the frequency of FRBs within our galaxy remains uncertain, Bochenek’s discovery highlights the role of serendipity in astronomical research. His antennas, costing around $15,000 and built from simple materials like metal pipes and cake pans, were designed to scan a large portion of the sky for the brightest radio flashes. Despite the odds, Bochenek struck gold after just one year of searching.
The Canadian observatory in British Columbia, with its more focused approach, was able to pinpoint the FRB's source to a magnetar in the constellation Vulpecula. This discovery not only provides insight into the nature of these enigmatic bursts but also opens the door to using them to map and understand the unseen material between galaxies, as noted by Jason Hessels, chief astronomer for the Netherlands Institute for Radio Astronomy.
While magnetars are now confirmed as a source of FRBs, astronomers acknowledge that other sources may exist, especially given the existence of two types of FRBs: those that occur once and those that repeat. Michilli's team has traced a repeating FRB that occurs every 16 days to a nearby galaxy and is close to pinpointing its exact origin.
The identification of a single FRB within our galaxy is a significant breakthrough, providing valuable data and insights. As Chatterjee remarked, "No one really believed that we'd get so lucky. To find one in our own galaxy just puts the cherry on top."
