In 2018, a black hole was observed with a sudden increase in its activity and rate of consuming material. It became much brighter in the visible light spectrum over the course of a few months.
Such a shift was believed to take thousands to millions of years, far longer than a human lifetime. Scientists have been closely watching for new phenomena, and 1ES 1927+654 has indeed delivered.
The black hole calmed by 2020 but dramatically increased its activity in 2023. Within just a few months, it emitted radio waves at 60 times its previous intensity, a behavior that has never been observed in real time for a supermassive black hole.
A large international team of scientists has observed a phenomenon that astronomers didn’t expect to see happen in real-time. A new study reports remarkable increases in radio emission in a few months and the formation of plasma jets extending from a black hole over a year.
Using Very Long Baseline Interferometry (VLBI), scientists captured high-resolution imaging of radio frequency emissions, showing two plasma jets forming near the black hole and expanding outward in 2023-2024. This is the first time jet formation has been observed in real-time.
A galaxy 270 million light-years away in the constellation Draco, called 1ES 1927+654, has caught scientists’ attention. Its center has an active black hole that was slowly gaining material until it suddenly sped up.
Our universe may be a bit more stable than was supposed
Some of the black holes discovered in recent years emit far more intensely at radio frequencies than when first observed. Scientists called them ‘changing-look AGN.’ Until now, changes in these objects were only observed years or decades apart, leading to assumptions about events in between. This new paper offers the first detailed look at how such changes occur.
Sometimes, black hole jets can extend far beyond their host galaxies and influence star formation. Understanding these jets helps us grasp the evolution of the universe and galaxies.
The new paper details real-time observations of a radio jet “turning on.” VLBI images show plasma blobs moving from the black hole, confirming it’s an outflow jet causing the radio flare. The jet moves at 20-30% of the speed of light.
Sibasish Laha, a research scientist, has studied changing-look AGN in X-rays. In 2020, he collaborated with Eileen Meyer, associate professor of physics at UMBC, to study 1ES 1927+654 and other similar galaxies. He is the lead author of a companion paper that includes more X-ray observations and interpretations of jet formation.
Laha said, “We still do not understand how black holes and their host galaxies interact with each other and co-evolve in cosmic time, and this study, for the first time, gives us the rare opportunity to understand how a supermassive black hole ‘talks’ to the host galaxy.”
In time-domain astronomy, time is critical. Meyer explains that it’s not for the faint-hearted, as rapid alerts require immediate follow-up. Regardless of the hour, swift action is essential because every hour matters. It’s a bit stressful, but crucial for this kind of work.
The project quickly became an “all hands on deck” effort for the UMBC team. Upon seeing the huge spike in radioactivity in 2023, Meyer and Laha realized something unprecedented was happening. They mobilized to use as many radio telescopes as possible to observe the source.
Due to the rapid changes in 1ES 1927+654, the team received unscheduled telescope observation time worldwide, typically planned months or years in advance.
Postdoctoral fellow Onic Shuvo, the paper’s third author, took on most of the late-night data analysis and observation requests. He’s thrilled to be part of this exciting discovery, which challenges existing models of AGN activity and highlights the role of changing-look AGN in understanding active galaxies.
The jets from 1ES 1927+654 are smaller than those in some powerful AGNs, but they are likely more common and important to understand. The 2018 flare might have been due to a “tidal disruption event,” where a star or gas cloud brightened the black hole. However, such events in already-active galaxies are rare.
Scientists are learning about smaller, shorter-lived jets called “compact symmetric objects” (CSOs). These jets might result from a single star or gas cloud ingestion and last about 1,000 years.
Meyer suggests that the recent data points to the birth of a new CSO. The tidal disruption event might have happened years ago, and it took some time for the black hole to start producing the jet, as seen in 2023-2024.
Meyer said, “Overall, “We still don’t understand after all these decades of studying these sources why only a fraction of accreting black holes produce jets and then exactly how they launch them. Until recently, we could not look into that innermost region to see what’s happening—how the accretion disk surrounding the black hole interacts with and produces the jet. And so there are still a lot of open questions there.”
Questions remain, but today, there are many promising models of how black holes produce jets, Meyer says. The next steps will include working with theorists to understand how the data from this study can help test and refine those models.
“There’s a lot of theoretical work to be done to understand what we’ve seen, but the good thing is that we have a massive amount of data,” Meyer says. “We’re going to keep following this source, and it’s going to continue to be exciting.”
Journal Reference:
- Eileen T. Meyer, Sibasish Laha, Onic I. Shuvo et al. Late-time Radio Brightening and Emergence of a Radio Jet in the Changing-look AGN 1ES 1927+654. The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/ad8651
Source: Tech Explorist
