A mysterious celestial entity has been discovered, potentially linking two astronomical enigmas: luminous fast-blue optical transients and tidal disruption events. The phenomenon, dubbed the ‘Platypus’, could also offer new insights into the origins of supermassive black holes.
The flash of light might also offer insight into the origins of supermassive black holes.
Astronomers don’t know what causes bright cosmic explosions called luminous fast-blue optical transients, or LFBOTs. A new cosmic burst suggests at least some might be from a mid-sized black hole ripping up a star.
The Enigmatic ‘Platypus’ Bursts
A bright blip in a distant galaxy may link two mysterious categories of cosmic flares. The event, which astronomers playfully call the Platypus, could also offer a new way to understand the origins of supermassive black holes that reside at the centers of most galaxies.
The brilliant burst, spotted in a dwarf galaxy about 6.5 billion light-years from Earth, has many of the hallmarks of a tidal disruption event – the final flash of a star being ripped apart by a black hole. But it also resembles another type of flash, dubbed an LFBOT, which astronomers think might be a class of exploding star.
Connecting the Dots
The Platypus could connect these two enigmatic events, according to astronomer Vikram Ravi of Caltech. The team wasn’t looking for LFBOTs or tidal disruption events around intermediate-mass black holes but stumbled upon something remarkable instead.
“These are the progenitors, or the seeds, of supermassive black holes,” says study coauthor Jean Somalwar, an astrophysicist at Caltech. Understanding these elusive beasts can illuminate how supermassive black holes formed.
Unraveling the Mystery
The team used the Palomar Observatory to find one promising flare in July and followed up with observations from the Hubble Space Telescope. The blast came from the outskirts of a tiny galaxy, shining brightly – 100 times that of all the stars in that galaxy.
“It’s just a remarkably bright source, brighter than really almost anything we’ve seen before,” Somalwar says. The burst might come from an extremely massive star “doing some crazy explosion” or a supermassive black hole shredding a star. But a galaxy that small probably lacks both. “We think an intermediate-mass black hole is a really good candidate,” she says.
The Platypus also looked like an LFBOT: It shone intensely in blue light, and it rose quickly in brightness. However, whereas the brightness of most LFBOTs evolves over a few days, the Platypus glowed for two weeks – more like a tidal disruption event.
Next Steps
The team hopes to get simultaneous observations with Hubble and the James Webb Space Telescope in the next month, which could help clarify the Platypus’s origins. The upcoming Vera Rubin Observatory in Chile should find hundreds more Platypus-like events if there are more to be found.
- sciencenews.org | A cosmic ‘Platypus’ might link two astronomical mysteries
