In the morning of October 9, astronomers’ inboxes pinged with a relatively modest alert: NASA’s Swift Observatory had just detected a fresh burst of energy, assumed to be coming from somewhere within our own Galaxy. But six hours later—when scientists realized an instrument on the Fermi Space Telescope had also flagged the event—another more pressing email arrived. “We believe that this source is now likely a gamma-ray burst,” it read. “This would suggest a highly energetic outburst, and therefore we strongly encourage follow-up.” In other words, this was a career-making chance to catch a rare celestial event in real time.
All over the globe, astronomers jumped into action. The world’s top astronomers were keen to see the powerful jetted explosion of some of our most exciting photons. “And by jetted, I mean like a firehose of emission,” says Wen-fai Fong, an astrophysicist at Northwestern University. These blasts are believed to have been caused by supernovae, which is a destructive collapsing that gives birth to black holes. The burst, dubbed GRB 221009A, went off about 2 billion light years away in the Sagitta constellation—one of the closest and most energetic ever observed—and it’s likely that one of the jets was fortuitously pointed directly at Earth. These factors combined made it possible to create a flash At least 10 times brighter than all the others spotted in the three decades since such bursts were discovered, leading some astronomers to dub it the “BOAT”—brightest of all time.
“I kept thinking, is this real? Because if it is, it’s an extremely rare, once-in-a-lifetime type of event,” Fong says. Fong and other researchers are busy collecting data to confirm the supernova’s origin and determine which star properties caused the explosion. Some theoretical thoughts have begun appearing on arXiv’s preprint server.
While detecting supernovae is now fairly common, it’s rarer to catch one in conjunction with a gamma-ray burst—they’re usually too faint to show up because they are so far away, and only a fraction of supernovae actually generate these explosions. However, supernovae are expected to appear very clearly due to the intensity of this explosion. “It’s really reinvigorated the community,” Fong says. “Everyone who has a telescope, even if they don’t normally study gamma-ray bursts, is trying to point their detectors at this to get the most complete dataset that we can.”
The blast produced several hundred second-long gamma radiation records. The next step was a series of low-energy photons. These included xrays and optical, infrared, and radio waves. It’s this afterglow that astronomers at ground-based telescopes are hungry to capture, because observing how the influx of photons changes over time will help them characterize the types of stars producing such bursts, the mechanisms driving these explosions, and the resulting environments they produce. These insights could shed light on what influence gamma-ray bursts have on future generations of stars, and determine whether stellar deaths make life possible for us on Earth by producing the heavy elements that can heat a planet’s interior and help sustain its magnetic field.
The emission is visible at almost all wavelengths of the light and can be observed by many instruments, making the gammaray burst postmortem a worldwide scientific phenomenon. Orbiting satellites like NASA’s NuSTAR are measuring its high energy x-rays, while sites like the Australia Telescope Compact Array are collecting the burst’s radio emission. “If we don’t get data one night, we can pretty much guarantee that someone will,” says Jillian Rastinejad, a Northwestern graduate student working with Fong. Together, they’re spearheading observations of visible light from the burst using the Gemini South telescope in Chile, data that will be supplemented by measurements from the Lowell Discovery Telescope in Arizona, South Korea’s Bohyunsun Optical Astronomy Observatory, and India’s Devasthal Fast Optical Telescope. Scientists even reported on Friday the infrared afterglow that was observed by the James Webb Space Telescope.