Unveiling the Enigma: The Finch - A Mysterious Intergalactic Burst of Light
08.10.2023 posted by Admin
A dazzling burst of light, generated by a mysterious cosmic explosion, illuminated the vast expanse between two galaxies, each more than 3 billion light-years away.
This remarkable optical flash, a radiant blue spectacle, shone briefly but brilliantly, marking a new instance of a rare and enigmatic astronomical event known as a luminous fast blue optical transient (LFBOT).
The LFBOT phenomenon remains largely shrouded in uncertainty. The initial sighting of one occurred as recently as 2018, designated as AT2018cow, residing 200 million light-years away in a spiral arm of its galaxy. Fondly nicknamed "the Cow," this phenomenon was astonishingly up to 100 times brighter than a typical supernova. Its brightness extended across radio waves, ultraviolet, and X-rays. However, it defied convention for supernovae by fading away within a few days, leaving astronomers puzzled.
These bursts of light, bearing animal-inspired nicknames based on their designations, surface at a rate of about one per year. Some notable examples include the Camel, the Koala, and the Tasmanian Devil. The most recent LFBOT, discovered on April 10 by the Zwicky Transient Facility at Palomar Observatory in California, was designated AT2023fhn, affectionately referred to as "the Finch."
Following the initial detection of the Finch, a meticulously planned series of observations ensued, involving telescopes both on the ground and in space. The Gemini South telescope in Chile conducted spectral analysis, revealing that the Finch had a temperature of 20,000 degrees Celsius (approximately 36,000 degrees Fahrenheit). This temperature, while significant, falls short of the extreme heat generated by massive stars and supernovae. Redshift measurements placed the Finch an astonishing 3 billion light-years away, a distance only resolvable by the Hubble Space Telescope, which subsequently unveiled a startling revelation: the Finch was not within a galaxy at all.
Previous LFBOTs had all been located in the spiral arms of galaxies, but Hubble's observations indicated that the Finch existed in the vast intergalactic void. Positioned roughly 50,000 light-years from a sizable spiral galaxy and 15,000 light-years from a smaller one, its location defied expectations that it could be the result of a massive star's supernova. While there are instances of rogue stars expelled from galaxies due to encounters with supermassive black holes, massive stars have relatively short lifespans, making it unlikely for one to traverse such vast distances.
Ashley Chrimes, a research fellow at the European Space Agency and the lead author of a newly published paper describing this perplexing LFBOT, expressed, "The more we learn about LFBOTs, the more they surprise us. We've shown that LFBOTs can occur a long way from the center of the nearest galaxy, and the location of the Finch is not what we expect for any kind of supernova."
Chrimes and his team are currently exploring two potential explanations. One hypothesis suggests that the Finch's luminous display resulted from a star being torn apart by an intermediate-mass black hole—a black hole with a mass ranging from 100 to a few thousand times that of our Sun. These intermediate-mass black holes are believed to inhabit the cores of certain globular star clusters situated on the outskirts of galaxies. Chrimes plans to employ the powerful James Webb Space Telescope to search for faint globular clusters in the same vicinity as the Finch.
Alternatively, the Finch might have been a kilonova, a cataclysmic event arising from the collision of two neutron stars or, in some cases, a neutron star and a black hole. Unfortunately, the Laser Interferometer Gravitational-Wave Observatory was inactive during this time, unable to detect any gravitational waves—ripples in spacetime—that could have been produced by such a collision. Given the Finch's staggering distance of 3 billion light-years, it may have been beyond the observatory's detection range. No associated gamma-ray burst was observed either.
Chrimes concluded, "The discovery poses many more questions than it answers. More work is needed to figure out which of the many possible explanations is the right one."
These findings are slated for publication in the journal Monthly Notices of the Royal Astronomical Society.
This remarkable optical flash, a radiant blue spectacle, shone briefly but brilliantly, marking a new instance of a rare and enigmatic astronomical event known as a luminous fast blue optical transient (LFBOT).
The LFBOT phenomenon remains largely shrouded in uncertainty. The initial sighting of one occurred as recently as 2018, designated as AT2018cow, residing 200 million light-years away in a spiral arm of its galaxy. Fondly nicknamed "the Cow," this phenomenon was astonishingly up to 100 times brighter than a typical supernova. Its brightness extended across radio waves, ultraviolet, and X-rays. However, it defied convention for supernovae by fading away within a few days, leaving astronomers puzzled.
These bursts of light, bearing animal-inspired nicknames based on their designations, surface at a rate of about one per year. Some notable examples include the Camel, the Koala, and the Tasmanian Devil. The most recent LFBOT, discovered on April 10 by the Zwicky Transient Facility at Palomar Observatory in California, was designated AT2023fhn, affectionately referred to as "the Finch."
Following the initial detection of the Finch, a meticulously planned series of observations ensued, involving telescopes both on the ground and in space. The Gemini South telescope in Chile conducted spectral analysis, revealing that the Finch had a temperature of 20,000 degrees Celsius (approximately 36,000 degrees Fahrenheit). This temperature, while significant, falls short of the extreme heat generated by massive stars and supernovae. Redshift measurements placed the Finch an astonishing 3 billion light-years away, a distance only resolvable by the Hubble Space Telescope, which subsequently unveiled a startling revelation: the Finch was not within a galaxy at all.
Previous LFBOTs had all been located in the spiral arms of galaxies, but Hubble's observations indicated that the Finch existed in the vast intergalactic void. Positioned roughly 50,000 light-years from a sizable spiral galaxy and 15,000 light-years from a smaller one, its location defied expectations that it could be the result of a massive star's supernova. While there are instances of rogue stars expelled from galaxies due to encounters with supermassive black holes, massive stars have relatively short lifespans, making it unlikely for one to traverse such vast distances.
Ashley Chrimes, a research fellow at the European Space Agency and the lead author of a newly published paper describing this perplexing LFBOT, expressed, "The more we learn about LFBOTs, the more they surprise us. We've shown that LFBOTs can occur a long way from the center of the nearest galaxy, and the location of the Finch is not what we expect for any kind of supernova."
Chrimes and his team are currently exploring two potential explanations. One hypothesis suggests that the Finch's luminous display resulted from a star being torn apart by an intermediate-mass black hole—a black hole with a mass ranging from 100 to a few thousand times that of our Sun. These intermediate-mass black holes are believed to inhabit the cores of certain globular star clusters situated on the outskirts of galaxies. Chrimes plans to employ the powerful James Webb Space Telescope to search for faint globular clusters in the same vicinity as the Finch.
Alternatively, the Finch might have been a kilonova, a cataclysmic event arising from the collision of two neutron stars or, in some cases, a neutron star and a black hole. Unfortunately, the Laser Interferometer Gravitational-Wave Observatory was inactive during this time, unable to detect any gravitational waves—ripples in spacetime—that could have been produced by such a collision. Given the Finch's staggering distance of 3 billion light-years, it may have been beyond the observatory's detection range. No associated gamma-ray burst was observed either.
Chrimes concluded, "The discovery poses many more questions than it answers. More work is needed to figure out which of the many possible explanations is the right one."
These findings are slated for publication in the journal Monthly Notices of the Royal Astronomical Society.