A fast blue optical transient (FBOT) is an explosion event similar to supernovas and gamma-ray bursts that presents high luminosity in blue light and evolves rapidly, reaching peak brightness and fading again in a matter of days, unlike supernovae which take weeks or months to dim[1][2][3]. FBOTs are the brightest known optical phenomenon in the universe and are a new class of cosmic explosions discovered in 2018[4]. They are also known as luminous fast blue optical transients (LFBOTs) [1].
FBOTs are a type of cosmic explosion initially detected in the optical wavelength. They fade almost as quickly as they appear, reaching peak brightness within a matter of days and then quickly fading[3]. They share some characteristics with supernova explosions of massive stars and with explosions that generate gamma-ray bursts (GRBs), but still have distinctive features[4].
The origins of FBOTs are still not well understood, but a new astrophysical model suggests that they might result from the actively cooling cocoons that surround jets from dying stars[3]. Another study suggests that FBOTs are potential probes of intermediate mass black holes[5].
Only a handful of previous FBOTs have been discovered since 2018, and they all happen inside galaxies where stars are being born[2]. However, the Hubble Space Telescope recently discovered an FBOT flash that happened between galaxies, which compounds the mystery of what these transient events are[2].
The explosion shown in the artist’s concept of a luminous fast blue optical transient is purely conjecture based on some known transient phenomenon because astronomers don’t know the underlying process behind FBOTs[2].
The recent discovery of a Luminous Fast Blue Optical Transient (LFBOT) by the Hubble Space Telescope has added to the mystery of these rare and strange bursts of extraordinarily bright light in the universe[1]. The LFBOT, nicknamed “the Finch,” was found far away from any host galaxy, in apparent isolation between two neighboring galaxies, which is a baffling locale for celestial objects previously thought to exist within host galaxies[1].
The Finch showed all the tell-tale characteristics of an LFBOT, shining intensely in blue light and evolving rapidly, reaching peak brightness and fading again in a matter of days, unlike supernovae which take weeks or months to dim[1]. The Hubble observations were crucial in identifying the Finch as unusual compared to other LFBOTs, as it was located in isolation between galaxies, unlike all previous LFBOTs that have been found in the spiral arms of galaxies where star birth is ongoing[1].
The discovery of the Finch has ruled out some possible theories and suggests that astronomers know even less about LFBOTs than previously thought[1]. Luminous Fast Blue Optical Transients are among the brightest known visible-light events in the universe, going off unexpectedly like camera flashbulbs, and only a handful have been found since the first discovery in 2018[1]. Presently, LFBOTs are detected about once per year[1].
The Finch was observed by multiple telescopes across the electromagnetic spectrum, from X-rays to radio waves, and spectroscopic measurements made with the Gemini South telescope in Chile found that the Finch is a scorching 20,000 degrees Celsius[1]. The LFBOTs could be the result of stars being torn apart by an intermediate-mass black hole (between 100 to 1,000 solar masses) [1]. The James Webb Space Telescope’s high resolution and infrared sensitivity might eventually be used to find that the Finch exploded inside a globular star cluster in the outer halo of one of the two neighboring galaxies, which is the most likely place an intermediate-mass black hole could be found[1].
To explain the unusual location of the Finch, the researchers are considering the alternative possibility that it is the result of a collision of two neutron stars, traveling far outside their host galaxy, that have been spiraling toward each other for billions of years[1]. Such collisions produce a kilonova, an explosion 1,000 times more powerful than a standard nova[1]. However, one very speculative theory is that if one of the neutron stars is highly magnetized, a magnetar, it could greatly amplify the power of the explosion even further to 100 times the brightness of a normal supernova[1].
The discovery of the Finch poses many more questions than it answers, and more work is needed to figure out which of the many possible explanations is the right one[1]. Because astronomical transients can pop up anywhere and at any time, and are relatively fleeting in astronomical terms, researchers rely on wide-field surveys that can continuously monitor large areas of the sky to detect them and alert other observatories like Hubble to do follow-up observations[1]. A larger sample is needed to converge on a better understanding of the phenomenon, say researchers[1].
Conclusion:
The discovery of the Luminous Fast Blue Optical Transient (LFBOT) “the Finch” by the Hubble Space Telescope has added to the mystery of these rare and strange bursts of extraordinarily bright light in the universe. The Finch was found far away from any host galaxy, in apparent isolation between two neighboring galaxies, which is a baffling locale for celestial objects previously thought to exist within host galaxies. The discovery of the Finch has ruled out some possible theories and suggests that astronomers know even less about LFBOTs than previously thought. LFBOTs are among the brightest known visible-light events in the universe, going off unexpectedly like camera flashbulbs, and only a handful have been found since the first discovery in 2018. Presently, LFBOTs are detected about once per year.
The Finch was observed by multiple telescopes across the electromagnetic spectrum, from X-rays to radio waves, and spectroscopic measurements made with the Gemini South telescope in Chile found that the Finch is a scorching 20,000 degrees Celsius. The LFBOTs could be the result of stars being torn apart by an intermediate-mass black hole (between 100 to 1,000 solar masses). The James Webb Space Telescope’s high resolution and infrared sensitivity might eventually be used to find that the Finch exploded inside a globular star cluster in the outer halo of one of the two neighboring galaxies, which is the most likely place an intermediate-mass black hole could be found.
To explain the unusual location of the Finch, the researchers are considering the alternative possibility that it is the result of a collision of two neutron stars, traveling far outside their host galaxy, that have been spiraling toward each other for billions of years. Such collisions produce a kilonova, an explosion 1,000 times more powerful than a standard nova. However, one very speculative theory is that if one of the neutron stars is highly magnetized, a magnetar, it could greatly amplify the power of the explosion even further to 100 times the brightness of a normal supernova.
The discovery of the Finch poses many more questions than it answers, and more work is needed to figure out which of the many possible explanations is the right one. Because astronomical transients can pop up anywhere and at any time, and are relatively fleeting in astronomical terms, researchers rely on wide-field surveys that can continuously monitor large areas of the sky to detect them and alert other observatories like Hubble to do follow-up observations. A larger sample is needed to converge on a better understanding of the phenomenon, say researchers. Upcoming all-sky survey telescopes may be able to detect more, depending on the underlying astrophysics.
In conclusion, the discovery of the Luminous Fast Blue Optical Transient “the Finch” has added to the mystery of these rare and strange bursts of extraordinarily bright light in the universe. The Finch was found in an unusual location, far away from any host galaxy, and its discovery has ruled out some possible theories and suggests that astronomers know even less about LFBOTs than previously thought. The Finch poses many more questions than it answers, and more work is needed to figure out which of the many possible explanations is the right one. Astronomy is a field that relies on continuous monitoring of the sky to detect astronomical transients and alert other observatories to do follow-up observations. A larger sample is needed to converge on a better understanding of the phenomenon.
Citations:
[1] https://esahubble.org/news/heic2309/
[2] https://hubblesite.org/contents/media/images/2023/024/01HBCED629B5QSGR03QM07EV9N?news=true
[3] https://news.northwestern.edu/stories/2022/04/dying-stars-cocoons-might-explain-fast-blue-optical-transients/
[4] https://www.sci.news/astronomy/fast-blue-optical-transients-08475.html
[5] https://ui.adsabs.harvard.edu/abs/2021cosp…43E1570C/abstract
[6] https://arxiv.org/abs/2307.01771