In a groundbreaking observation, astronomers have witnessed a galaxy, SDSS1335+0728, dramatically "turn on the lights" after a 20-year slumber, marking the first real-time observation of a massive black hole awakening. The galaxy SDSS1335+0728, located approximately 300 million light-years away in the constellation Virgo, began exhibiting dramatic changes in brightness in late 2019, as detected by the Zwicky Transient Facility.
Its core, powered by a black hole one million times the Sun's mass, began radiating intense light across ultraviolet, optical, and infrared wavelengths, and by February 2024, it emitted X-rays, signalling unprecedented activity. This phenomenon, detailed in Astronomy & Astrophysics, suggests the black hole started feasting on surrounding gas, transforming the galaxy into one with an active galactic nucleus (AGN).
According to Earth.com, researchers utilised data from multiple observatories, including the European Southern Observatory's Very Large Telescope, to monitor the galaxy's transformation.
"Imagine you've been observing a distant galaxy for years, and it always seemed calm and inactive. Suddenly, its core starts showing dramatic changes in brightness, unlike any typical event we've seen before," said Paula Sanchez Saez, an astronomer at ESO in Germany and lead author of the study accepted for publication in Astronomy & Astrophysics.
This event marks the first real-time observation of a black hole transitioning from a quiescent to an active state, providing invaluable insights into the behaviour of these cosmic giants. Co-author Claudio Ricci noted that such "giant monsters" typically remain dormant and invisible, making this a rare glimpse into black hole activation.
Alternative explanations, like a prolonged tidal disruption event where a star is shredded by the black hole, are being explored, but the sustained brightness over years sets this apart from typical flares, which fade within months.
Profound Implications
This observation could refine models of black hole growth and galaxy evolution, offering clues about how these cosmic giants influence star formation. Researchers are using advanced telescopes, like the European Southern Observatory's Very Large Telescope, to gather more data, hoping to confirm whether this is a new class of outburst or a slow tidal event. Each scenario would require revising models of black hole accretion and the frequency of black hole awakenings in the present-day universe.
"Regardless of the nature of the variations, this galaxy provides valuable information on how black holes grow and evolve. We expect that instruments such as MUSE on the VLT and those on the upcoming Extremely Large Telescope will be key to understanding why the galaxy is brightening," Sanchez Saez added.
