A recent observation by the Hubble Space Telescope has left astronomers puzzled. A luminous fast blue optical transient (LFBOT), designated as AT2023fhn and nicknamed “the Finch,” was detected in the space between two galaxies over 3 billion light-years away.
Unlike
previous LFBOTs, which were usually found in the spiral arms of galaxies, the
Finch was located in intergalactic space, making it an anomaly among its kind.
What Are LFBOTs?
LFBOTs
are a rare class of astronomical events that were first discovered in 2018.
These events are characterized by a brilliant flash of blue light that fades
away within a few days. The first LFBOT, designated AT2018cow and nicknamed
“the Cow,” was up to 100 times brighter than an ordinary supernova and
displayed unusual behavior across various wavelengths, including radio waves,
ultraviolet, and X-rays.
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The
Hubble Space Telescope’s image of the Finch and its location near two galaxies.
(Image credit: NASA/ESA/STScI/A. Chrimes (Radboud University))
The Enigma of the Finch’s Location
The
Finch’s unique location, about 50,000 light-years from one large spiral galaxy
and 15,000 light-years from a small galaxy, challenges existing theories.
Massive stars, which could potentially go supernova, live only a few million
years—insufficient time for a star to be flung into intergalactic space
following an encounter with a supermassive black hole.
Theories and Future Investigations
Researchers
are currently considering two possible explanations for the Finch’s occurrence.
One theory suggests that it could be a star being torn apart by an
intermediate-mass black hole, which resides at the cores of some globular star
clusters. Another possibility is that the Finch was a kilonova, resulting from
the collision of two neutron stars or a neutron star and a black hole. Further
observations using the James Webb Space Telescope are planned to explore these
theories.
The discovery of the Finch adds another layer of complexity to our understanding of LFBOTs and challenges existing astronomical theories. As Ashley Chrimes, a research fellow at the European Space Agency, stated, “The more we learn about LFBOTs, the more they surprise us.”