Astronomers at the European Southern Observatory have tracked changes in the galaxy's brightness using data from several space and ground-based observatories, such as the Very Large Telescope (VLT). According to the study published in the journal Astronomy & Astrophysics, the changes observed in the galaxy are likely the result of the sudden awakening of the supermassive black hole at its centre.
Imagine that you have been observing a distant galaxy for years, and it has always seemed quiet and inactive. Suddenly, its [core] Dramatic changes in brightness begin to appear, unlike any normal phenomenon we have seen before,
Paula Sánchez Sáez, astronomer and lead author of the study, European Southern Observatory
This is what happened with SDSS1335+0728, which rapidly brightened in December 2019 and is now classified as an “active galactic nucleus” (AGN), a bright, compact region powered by a massive black hole.
Some events, such as supernova explosions or tidal disruption events – when a star gets too close to a black hole and is torn apart – can cause galaxies to suddenly brighten. However, these changes in brightness usually only last for a few hundred or a few dozen days at most.
Four years after it was first “switched on,” SDSS1335+0728 continues to get brighter. The galaxy, which is located 300 million light-years away in the constellation Virgo, also shows fluctuations that have never been seen before, leading astronomers to believe in an alternative explanation.
The group used archival data as well as new observations from a number of facilities, including the X-shooter instrument on ESO's VLT in the Atacama Desert in Chile, to explain these brightness changes.
They found that SDSS1335+0728 is emitting significantly more light at ultraviolet, optical, and infrared wavelengths when comparing data collected before and after December 2019. In February 2024, the galaxy also began emitting X-rays into space.
,This behavior is unprecedented” said Sánchez Sáez, who is also affiliated with the Millennium Institute of Astrophysics (MAS) in Chile.
The most convincing option to explain this phenomenon is that we are looking at how [core] Activity has begun to appear in the galaxy. If this happens, it will be the first time we will see the activity of a giant black hole in real time,
Lorena Hernández García, study co-author, Valparaiso University
Supermassive black holes, most of which are found at the center of galaxies such as the Milky Way, have masses more than 100,000 times the mass of the Sun.
These giant monsters are usually sleeping and not directly visible. In the case of SDSS1335+0728, we were able to see the awakening of the giant black hole, [which] Suddenly it started depending on the gas available around it, and became very bright,
Claudio Ricci, study co-author, Diego Portales University
,[This] This process has never been seen before” Hernández García said.
This is the first time the process of a black hole awakening has been observed in real time; previous research has shown that dormant galaxies can become active after just a few years.
Ricci, who is also affiliated with the Kavli Institute for Astronomy and Astrophysics at Peking University in China, said, “Something similar may be happening with our own Sgr A*, a supermassive black hole at the center of our galaxy.But it's unclear how likely that is to happen.
Additional observations are still needed to rule out other possibilities. Another possibility is the observation of an unusually slow tidal disruption event or perhaps a new event. The duration and slowness of this event make it the longest and slowest known tidal disruption event.
Saez said,Whatever be the nature of the variations, [this galaxy] provides valuable information about how black holes grow and evolve. We expect that instruments such as [MUSE on the VLT or those on the upcoming Extremely Large Telescope (ELT)] will be important to understand [why the galaxy is brightening],
Journal Reference:
Saez, S.P., and others. (2024) SDSS1335+0728: Awakening of ~106 M_sun Black Hole. Astronomy and Astrophysicsdoi.org/10.1051/0004-6361/202347957
Source:
https://www.eso.org/public/