In 2018, a galaxy located approximately 270 million light-years from Earth experienced a significant surge in activity, quieting down by 2020 before ramping up dramatically again in 2023. During this latter period, it started radiating radio waves at an intensity 60 times greater than before within a matter of months. This type of behavior has never been observed in real time for a supermassive black hole. Additionally, imaging revealed the formation of plasma jets moving in opposite directions near the black hole, expanding throughout 2023 and 2024. This real-time observation of jet formation is unprecedented. The collected data will assist researchers in comprehending how and under what specific conditions black holes release jets.
An extensive international research team has witnessed an event in astronomy that was thought to be impossible to capture in real time. These groundbreaking findings are detailed in a recent study published in Astrophysical Journal Letters, spearheaded by Eileen Meyer, an associate professor of physics at UMBC.
The excitement centers around a galaxy known as 1ES 1927+654, situated in the Draco constellation and 270 million light-years away from Earth. For years, this galaxy was categorized as an “active galactic nucleus,” or AGN, indicating the presence of a highly active black hole at its center. Initially, this black hole was slowly accumulating material, but that changed significantly.
In 2018, the black hole gained notoriety as it exploded into activity, dramatically increasing the rate at which it was consuming material and surpassing its previous brightness by over 100 times in just a few months. Such a rapid change was thought to occur over thousands to millions of years; hence, scientists have since monitored it closely for further remarkable occurrences, and 1ES 1927+654 has not disappointed.
More drama
After the notable surge in activity in 2018, which included nearly a year of exceptionally high X-ray emissions, the black hole calmed by 2020 before its intensity shot up again in 2023. This resurgence included the emission of radio waves at a remarkable intensity, 60 times greater than previously recorded in just a few months—a behavior never observed in real time from a supermassive black hole.
High-resolution imaging of radio frequency emissions was achieved using a method known as Very Long Baseline Interferometry (VLBI), which clearly captured a pair of plasma jets forming near the black hole and rapidly expanding from 2023 into 2024. Notably, this marks the first documentation of jet formation in real time.
In recent years, a handful of supermassive black holes have been noted for their elevated radio frequency emissions, leading researchers to label them “changing-look AGN.” Historically, these observations were made at two distinct intervals years or decades apart, leaving a gap in understanding what transpired in between. This new publication offers the first detailed insight into how these significant changes happen.
Turning on in real time
According to Meyer, black hole jets can extend to vast distances outside their host galaxies and influence star formation processes. Understanding the mechanics of these jets is crucial for comprehending the broader evolution of the universe and the formation of galaxies.
In the study discussed in the paper, “We have very precise observations depicting a radio jet ‘activating’ in real time, and particularly exciting are the VLBI observations that vividly exhibit these plasma blobs ejecting from the black hole,” Meyer explains. “This indicates a genuine outflow jet of plasma is responsible for the radio flare, rather than another process causing the increased radio emissions. This jet is likely moving at about 20 to 30 percent the speed of light and originates very close to the black hole, which is quite thrilling.”
Sibasish Laha, an assistant research scientist at UMBC and the second author of the new study, has extensively investigated changing-look AGN at X-ray wavelengths. He believed the radio frequency emissions from 1ES 1927+654 might reveal intriguing patterns, prompting him to collaborate with Meyer to explore 1ES 1927+654 and similar galaxies in 2020. He is also the lead author of a related paper currently under review, which includes additional X-ray observations and context regarding the jet formation event.
“Our understanding of how black holes interact with their host galaxies and how they both evolve over cosmic time is still very limited,” Laha notes. “This study offers us a unique opportunity to gain insight into how a supermassive black hole communicates with its galaxy.”
Not for the faint of heart
The urgency of time in this sort of research is paramount. Meyer states that “time-domain astronomy” is not for the timid. “Rapid alerts lead to immediate follow-ups. When something happens, you need to react quickly, regardless of the hour; every moment matters, which can be quite stressful.”
This project required a full-force response from the UMBC team. Upon witnessing the significant surge in radio activity in 2023, Meyer recalls their reaction: “We were astonished—something extraordinary was unfolding. This was unprecedented. Our excitement propelled us to enlist as many radio telescopes as possible to observe this phenomenon.”
The swift changes in 1ES 1927+654 allowed the team to secure unscheduled observations from telescopes across the globe, which is uncommon due to the usual requirement that telescope time be booked months or even years in advance.
Onic Shuvo, a postdoctoral researcher working with Meyer and the third author of the paper, undertook most of the late-night tasks, swiftly analyzing incoming data and requesting new observations. He is exhilarated to contribute to such a significant discovery. “This finding challenges current AGN activity models and underscores the critical role changing-look AGN have in resolving the mysteries of active galaxies’ central engines in real time,” Shuvo expresses.
A new jet is born
The recently formed jets from 1ES 1927+654 are relatively minor when compared to the massive jet structures observed in some of the most potent AGN. However, Meyer argues this doesn’t diminish their significance; instead, they are probably more common throughout the universe and warrant further exploration.
Some data implies that the visible light flare in 2018 could be attributed to a “tidal disruption event,” where a large object like a star or gas cloud ventures too close to an inactive black hole, temporarily brightening it. However, recorded observations of tidal disruption events in already-active galaxies are rare and not well-documented.
While larger plasma jets can extend far beyond their host galaxies and persist for millions of years, scientists are also recognizing a new class of smaller, shorter-lived jets termed “compact symmetric objects,” or CSOs. Meyer proposes that the available data strongly suggests the formation of a new CSO. A contemporary hypothesis posits that jets in CSOs differ fundamentally from those vast and long-lived jets seen elsewhere, likely resulting from a singular ingestion of a star or gas cloud—essentially, a single tidal disruption that powers this brief jet for roughly 1,000 years.
It’s plausible that the tidal disruption event occurred several years back, and it took some time for the accreting black hole to stabilize and begin producing the jets seen in 2023 and 2024, as Meyer suggests.
Open questions
Overall, Meyer adds, “Despite decades of study, we still don’t fully grasp why only a small fraction of accreting black holes produce jets and how these jets are launched. Until recently, we lacked the means to observe the most inner regions to understand the interaction between the accretion disk surrounding the black hole and the jet’s generation. There remain numerous unanswered questions.”
While uncertainties persist, a variety of promising models explaining how black holes generate jets have emerged, according to Meyer. Future endeavors will focus on collaborating with theorists to refine and test these models against the data collected from this study.
“There’s substantial theoretical work ahead to interpret what we’ve observed, but fortunately, we have an abundance of data,” Meyer concludes. “We will continue our observations of this source, and it promises to remain an exhilarating journey.”
