Webb telescope uncovers cosmic 'fireworks' at Milky Way's heart
The supermassive black hole at the centre of our galaxy, the Milky Way, although not as "voracious" as others on the fringes of the universe, is surrounded by spectacular "fireworks" – new data from the Webb Space Telescope reveals.
The latest data from the James Webb Space Telescope (JWST) shows that the environment around the black hole pulses with "fireworks." Scientists have analysed strange bursts that occur around the supermassive black hole Sagittarius A* in the central part of our Milky Way galaxy. Telescope readings in two near-infrared bands reveal cosmic bursts that vary in brightness and duration.
Five to six bursts per day around the black hole
According to scientists, the disk full of scattered materials and hot gas surrounding the black hole, generates five or six large bursts per day, with several smaller explosions in between. These observations have been detailed in the scientific publication "The Astrophysical Journal Letters."
The data indicates that dynamically changing brightness often increases in sudden bursts, only to recede again – as noted during research conducted by Farhad Yusef-Zadeh from Northwestern University. The observed profile of the black hole's activity turned out to be quite random and novel each time.
Yusef-Zadeh and his team studied Sagittarius A* with the near-infrared camera (NIRCam) for 48 hours, expecting to see bursts. Although they anticipated these flares might appear, they did not predict how intense the activity surrounding the black hole would be.
What causes the bursts around the black hole?
Researchers suggest that two separate processes may cause this light display. Smaller flares may result from turbulence in the disk surrounding the black hole, which, by compressing hot, magnetised gas, may generate short bursts of radiation, akin to solar flares.
Large explosions, on the other hand, may result from magnetic reconnection (a phenomenon where magnetic field lines from different regions connect, leading to the release of a significant amount of energy), when colliding magnetic fields eject particles at speeds close to the speed of light. Similar to the sparking of static electricity, this process generates a "reconnection spark."
An unexpected observation was how the brightness of the bursts changed at two different wavelengths – scientists note. It was observed that events in shorter wavelengths changed brightness slightly faster than those in longer wavelengths. This may provide clues about the physical processes occurring in the disk around the black hole. Likely, particles from the flares lose energy more rapidly at shorter wavelengths, as anticipated for particles orbiting magnetic field lines.
Researchers will continue to track the mysterious bursts
Researchers now aim to obtain longer observation periods with the James Webb Telescope, which could reduce noise and provide a more precise picture of the centre of our galaxy. The study's lead author, Yusef-Zadeh, noted that managing noise is crucial with such faint flares and expressed hope that longer observations will unveil previously unseen features and determine whether the bursts are recurring or entirely random.
