Astrophysicists Gustavo Magallanes-Guijón and Sergio Mendoza from the Universidad Nacional Autonoma de Mexico have detected regular gamma radiation pulses originating from the vicinity of Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, using data from the Fermi Gamma-ray Space Telescope.
The research findings, presented in a paper on the arXiv preprint server, unveil a hitherto unnoticed phenomenon near the stable black hole Sgr A*. It does not actively attract materials or emit plasma jets; instead, a recent study discovered a gas blob in orbit around the black hole at a distance comparable to Mercury's orbit around the Sun.
Gamma-Ray Mystery: Milky Way's Anomalous Emissions
In 2021, researchers detected gamma-ray radiation pulses emanating from the vicinity of Sgr A*, the supermassive black hole at the center of the Milky Way.
Recognizing that the radiation couldn't originate from within the black hole itself due to the constraints of the event horizon, a boundary beyond which nothing, not even light, can escape the immense gravitational pull of the black hole, the team inferred that the gamma rays must be emitted from the surrounding environment of Sgr A*.
While other supermassive black holes are known to emit powerful radiation from their immediate surroundings through the generation of turbulent conditions in nearby gas and dust, forming an accretion disk, this model doesn't apply to Sgr A*.
The Milky Way's black hole is enveloped by sparse matter, and its slow feeding rate is likened by University of Arizona astronomer Chris Impey, who was not involved in the study, to a human subsisting on a diet of one grain of rice every million years, making the traditional accretion disk explanation insufficient for explaining the observed gamma-rays.
Rapidly Orbiting Gas Blob Unveils Secrets of Milky Way's Black Hole
Their approach involved analyzing publicly available data from the Fermi Gamma-ray Space Telescope collected between June and December 2022 to investigate the origin of gamma-rays detected near Sagittarius A*. They focused on processing and identifying periodic patterns.
Through this analysis, they identified a noteworthy pattern: a pulse of gamma radiation reaching Earth approximately every 76.32 minutes, with a periodicity closely linked to half of the recorded X-ray flares also originating near Sagittarius A*.
The researchers propose that both the gamma-rays and X-rays are likely emitted by a rapidly moving gas blob orbiting Sgr A* at nearly 30% of the speed of light. This blob is believed to emit radiation across various wavelengths and periodically flare as it orbits the supermassive black hole.
The newfound understanding, characterized as a "unique oscillatory physical mechanism," leads the researchers to conclude that the emissions result from a swirling gas blob, traveling at approximately 200 million mph (320 million km/h) around Sgr A*. This discovery offers insights into the environments surrounding supermassive black holes, particularly those with lower feeding rates, such as the one at the center of the Milky Way.
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