In December 2019, a little-known galaxy called SDSS 1335+0728, located 300 million light-years away in the constellation Virgo, suddenly started glowing brighter than ever before. To understand why, astronomers used data from multiple space and ground-based observatories to track the changes in the galaxy's brightness. They concluded that they were witnessing the sudden awakening of the supermassive black hole at its center.
This artist's impression shows the black hole drawing in the surrounding gas, growing a disk of material that lights up the galaxy. Image credit: ESO/M. Kornmesser.
“Imagine observing a distant galaxy for years and it always seemed quiet and inactive,” said Dr Paula Sánchez Sáez, astronomer at ESO and the Millennium Astrophysics Institute.
“Suddenly, the brightness of its central core began to change dramatically, which is not a typical phenomenon we've seen before.”
This is what happened to SDSS 1335+0728, which has been classified as having an active galactic nucleus (AGN) after brightening dramatically in December 2019.
Galaxies can suddenly brighten due to events such as supernova explosions or tidal disruption, but these changes in brightness usually only last for a few tens or, at most, a few hundred days.
SDSS 1335+0728 continues to grow brighter, more than four years after it was first observed “lighting up.”
What's more, the changes detected in the galaxy are unlike anything seen before, suggesting alternative explanations to astronomers.
Dr Sáez and his colleagues sought to understand these brightness changes by combining archival data with new observations from several facilities, including the X-SHOOTER instrument on ESO's Very Large Telescope.
Comparing data taken before and after December 2019, we found that SDSS 1335+0728 now emits much more light in ultraviolet, visible and infrared wavelengths, and the galaxy also began emitting X-rays in February 2024.
“This kind of action is unprecedented,” Dr. Saez said.
“The most concrete option to explain this phenomenon is that we are seeing the galactic core starting to show activity,” added Dr Lorena Hernández GarcÃa, an astronomer at the Millennium Institute for Astrophysics and ValparaÃso University.
“If this is the case, it would be the first time that we have observed the activation of a massive black hole in real time.”
“Supermassive black holes are normally dormant and cannot be seen directly,” said Dr Claudio Ricci, an astronomer at the Diego Portales University and the Kavli Institute for Astronomy and Astrophysics at Peking University.
“In the case of SDSS 1335+0728, we were able to observe a massive black hole awakening and suddenly absorbing the surrounding gas, becoming extremely bright.”
“This process has never been observed before,” Dr. Garcia said.
“Previous studies have reported that dormant galaxies become active after a few years, but this is the first time that the process of black hole awakening itself has been observed in real time.”
“This could also happen to Sagittarius A*, the supermassive black hole at the centre of our Milky Way galaxy, but we don't know how likely this is to happen.”
“Regardless of the nature of the fluctuations, SDSS 1335+0728 will provide valuable information about how black holes grow and evolve,” said Dr. Sáez.
“We hope that instruments like MUSE on the VLT and the upcoming MUSE on the Extremely Large Telescope (ELT) will hold the key to understanding why galaxies are brightening.”
of study Published in a journal Astronomy and Astrophysics.
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P. Sanchez Aes others2024 SDSS1335+0728: The awakening of the universe about 1 billion years ago6 M_sun Black hole. A&Ain press; doi: 10.1051/0004-6361/202347957
Source: www.sci.news
