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A newly discovered cosmic event, dubbed AT2024wpp or “the Whippet,” is challenging existing understandings of energetic explosions in the universe. Astronomers utilizing the Atacama Large Millimeter/submillimeter Array (ALMA) and other radio observatories have detected dense gas surrounding this exceptionally luminous event, material previously thought to be absent and only visible through radio and millimeter wavelengths.
The findings, presented at the American Astronomical Society’s annual meeting this January, reveal that AT2024wpp belongs to a rare class of phenomena known as Luminous Fast Blue Optical Transients (LFBOTs). These events are characterized by their rapid brightening and fading, releasing immense amounts of energy far exceeding typical stellar explosions.
“Even though we suspected what it was, it was still extraordinary,” stated a principal investigator of the study. “This was many times more energetic than any similar event and more than any known explosion powered by the collapse of a star.”
Unveiling the Invisible: The Whippet’s Discovery
First identified in September 2024 by the Zwicky Transient Facility, AT2024wpp initially appeared as a very hot, blue source emitting strong X-rays. Early observations using optical telescopes revealed surprisingly little surrounding material. This apparent lack of surrounding matter presented a puzzle for astronomers.
However, subsequent observations with ALMA and the National Science Foundation’s Very Large Array revealed a crucial piece of the puzzle: a fast-moving shock wave expanding at roughly one-fifth the speed of light into a dense region of gas near the explosion. This gas remained hidden from optical telescopes due to the intense X-ray radiation emitted by the event. The radiation stripped electrons from the atoms, effectively suppressing the usual spectral signatures detectable in optical light, while leaving radio emissions intact.
Black Hole Accretion: A Leading Explanation
The observations strongly support a scenario involving a massive black hole actively accreting material from a companion star. Prior to the catastrophic disruption, the star is believed to have expelled large quantities of gas, forming a dense shell around the system. When the star was ultimately torn apart, the resulting debris produced the observed burst of energy.
Subsequent spectroscopic observations confirmed the presence of high-velocity hydrogen and helium, further bolstering the evidence for dense gas in the immediate vicinity of the explosion.
Implications for Black Hole Research
This discovery has significant implications for our understanding of black holes and their role in the universe. “Not only do these events help us identify black holes, but they also provide a new way to identify where black holes occur and how they form and grow, and the physics of how this happens,” the principal investigator added.
The ability to detect these events through radio and millimeter wavelengths, even when obscured from optical view, opens up new avenues for identifying and studying black holes throughout the cosmos. This is particularly important as many black holes are thought to be hidden from view by surrounding gas and dust.
This research was published as “AT2024wpp: An Extremely Luminous Fast Ultraviolet Transient Powered by Accretion onto a Black Hole” by Daniel A. Perley et al. The findings are based on a press release from the National Radio Astronomy Observatory of the United States, an ALMA partner, and the Astrophysics Research Institute at Liverpool John Moores University.
ALMA, an international astronomy facility, is a collaboration between the European Southern Observatory (ESO), the U.S. National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) of Japan, in cooperation with the Republic of Chile. The facility’s construction and operations are jointly led by ESO, the National Radio Astronomy Observatory (NRAO), and the National Astronomical Observatory of Japan (NAOJ).
Image of AT2024wpp before and after outburst A new, extremely luminous fast blue optical transient, AT2024wpp, flares as a bright blue point of light in the left panel, located just off the edge of its faint host galaxy, while the right panel shows the same region of sky after the outburst faded. Credit: Astrophysics Research Institute, Liverpool John Moores University/Daniel A. Perley
The detection of the Whippet and its surrounding gas represents a significant step forward in unraveling the mysteries of the universe’s most powerful explosions and the enigmatic black holes that power them.
