The Hubble Telescope has captured a massive intergalactic explosion that astronomers still can’t explain

a A mysterious cosmic explosion Create a bright flash of light in space between two galaxies more than 3 billion light-years away.

he Optical flashone of the brightest bursts of blue light in the universe recorded It only lasted a few days It’s the latest example of a rare type of brief astronomical event called a “fast luminous blue light transient” (LFBOT). Their findings have been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society.

LFBOTs are a complete mystery. The first discovery was not observed until 2018. Designated AT2018cow, it is located in the spiral arm of its galaxy 200 million light-years away. Nicknamed “The Cow” It was up to 100 times brighter than a normal supernova. It also glowed in radio waves, ultraviolet light and X-rays, and if it had been a supernova, it would have behaved very strangely. Normally, a supernova stays bright for weeks or even months, and has a recognizable spectrum. However, the cow faded away after a few days.

Scientists discover similar bursts of light at a rate of about one per year, and the animals are named based on the last three letters of their name. Other LFBOTs have been named Camel, koala and Tasmanian devil. The latest LFBOT, discovered by the Zwicky Transient Facility at Palomar Observatory in California on April 10, has been named AT2023fhn and thus given the name “Sparrow.”

After the initial detection of LFBOT, a pre-planned series of observations were made using ground-based and space-based telescopes. he Gemini South Telescope in Chile Finch measured the spectrum and found it The temperature was 20 thousand degrees Celsius (about 36,000 degrees Fahrenheit), which is hot, but not as hot as some massive stars and certainly not as hot as a supernova.

Redshift measurements place it about 3 billion light-years away, a distance so great that only the Hubble Space Telescope can discern its host galaxy. When this happened, astronomers made a surprising observation: Finch wasn’t in any galaxy.

All previous LFBOTs had been observed in the spiral arms of galaxies, but Hubble noticed that Finch was in intergalactic space, About 50,000 light-years from a large spiral galaxy and 15,000 light-years from a small galaxy.

Its location seems to belie the possibility that it was a supernova of an exploding massive star. Although there is Rogue stars are expelled from the galaxy into intergalactic space After colliding with a supermassive black hole, massive stars live only a few million years before going supernova, which is not enough time for the star to travel all the way.

“The more we know about LFBOTs, the more they surprise us,” Ashley Kremes, an ESA researcher and lead author of a new paper describing the recently observed LFBOTs, said in a statement. “We have shown that LFBOTs can occur at large distances from the center of the nearest galaxy, and Finch’s location is not what we would expect for any type of supernova.”

Chrisms and his team focus on two possible explanations. One is that The finch was a flash of light produced by a star being torn apart by a black hole Of medium mass, it is a black hole whose mass ranges between 100 and a few thousand times the mass of the Sun. Intermediate-mass black holes are thought to reside at the heart of some globular star clusters, which lie on the outskirts of galaxies. Chrimes plans to eventually use the powerful optics of the James Webb Space Telescope to search for faint globular clusters in the same location as Finch.

Alternatively, it could be a Finch kilonova, the explosion resulting from the collision of two neutron stars (or sometimes between a neutron star and a black hole).

The gravitational wave observatory with a laser interferometer was not operational at that time Detecting potential gravitational waves, or waves in space-time, Coming from a neutron star merger (its last observing run began in May). At 3 billion light-years away, Finch was probably too far away to be detected anyway. No associated gamma-ray burst has been detected.

“This discovery raises many more questions than it answers. More work is needed to discover which of several possible explanations is correct.”