We may know much less about the strange cosmic explosion than we thought.
They are called luminous fast blue visual transients, or LFBOTs, and one bird (AT2023fhn) is observed in interstellar space at great distances from the nearest galaxy.
This is a problem, because astronomers thought LFBOTs might be a type of massive supernova, something that already happened within the confines of the galaxy.
“The more we learn about LFPODs, the more they surprise us.” says astronomer Ashley Grimes European Space Agency and Radbot University in the Netherlands.
“We have now shown that LFPODs can occur far from their nearest galaxy, and Finch’s location is not what we would expect for a supernova.”
The first LFBOT was discovered in 2018, and since then we’ve discovered quite a few more. With each new discovery, LFBOT continues to puzzle scientists. These space explosions are very bright – at least 10 times brighter than a normal supernova – and very short.
Normal supernovae peak and fade over weeks or months; LFBOT devices are like camera flashes in space. And they are very hot. This is what gives them their blue color.
An artist’s impression of AT2023fhn, also known as The Finch. (NASA, ESA, NSF’s NOIRLab, M. Garlick, M. Zamani)
Scientists thought these events might have been caused by an unusual type of collapse supernova, in which the core of a dying star collapses directly into a neutron star or black hole. This would require a large progenitor star, At least eight times the mass of the Sun.
Another possibility is that the flashes may be caused by the black hole swallowing another ultra-dense object. White dwarf star.
Big stars don’t live long Main sequence Spirits. that it Less than 100 million years ago The star has a mass eight times that of the Sun. They were born in areas dense with gas and dust, which are galaxies. he’s there Not so much in intergalactic space.
Although some stars can deorbit and outpace the velocities of their host galaxies, the progenitors of massive neutron stars and black holes are not expected to get this far before their recent supernovae.
In fact, all previous LFBOTs have been found in the spiral arms of galaxies where star formation occurs, which is where one would expect to find a supernova.
This brings us to Finch’s problem. It was discovered by the Zwicky Transient Facility on April 10, 2023. Its temperature was measured at 20,000 degrees Celsius (about 36,000 Fahrenheit). Hubble was called in to find out its source. This is where things started to go a little slow.
The explosion occurred about 2.86 billion light-years away, but in intergalactic space, about 50,000 light-years from the nearest spiral galaxy and 15,000 light-years from the nearest dwarf galaxy belonging to that spiral galaxy. This poses a major challenge to the supernova hypothesis.
Hubble image of Finch. (NASA, ESA, STScI, A. Krems/Radboud University)
But the black hole hypothesis is still on the table. Researchers say it’s possible that an ancient, isolated ball of stars, called a globular cluster, could be lurking in intergalactic space.
Globular clusters are thought to be entangled with black holes, a rare type of intermediate mass. If there were a globular cluster, too faint to see, we might have been blindly targeting one of these black holes.
Another possibility is that the explosion was the result of a collision between two neutron stars, one of which was probably a magnet, and whose intense magnetic field could have amplified the resulting kilonova. Theoretical analysis should be conducted to determine the plausibility of this scenario.
“The results raise more questions than they answer.” She says crimes. “More work is needed to determine which of several possible explanations is correct.”
One thing is certain, though. The more we discover these things, the stranger they become.
The search has been accepted Monthly Notices of Letters of the Royal Astronomical SocietyAnd available arXiv.
