For the first time, astronomers have successfully probed the intriguing physical environment surrounding repeating X-ray outbursts associated with supermassive black holes, thanks to innovative data from NASA’s Neutron star Interior Composition Explorer (NICER) and other significant missions. The study of these phenomena, termed quasi-periodic eruptions (QPEs), reveals a new layer of complexity and excitement in our understanding of the cosmos. Among the recent discoveries is a newly identified system, affectionately named Ansky, which stands out as the eighth QPE source cataloged, generating the most energetic outbursts recorded to date.
Ansky has established remarkable records in both temporal and energetic scales, exhibiting eruptions approximately every 4.5 days that persist for around 1.5 days. This rhythm of activity is unlike anything previously observed, captivating the attention of astrophysicists and provoking urgent inquiries into the mechanisms responsible for these extraordinary outbursts. Joheen Chakraborty, a graduate student from the Massachusetts Institute of Technology (MIT), articulated the puzzle posed by these phenomena, emphasizing the importance of the quasi-periodic trait that characterizes QPEs. The scientific community is still in the early stages of developing frameworks and methodologies to unravel the underlying causes of QPEs, and the unique characteristics of Ansky are proving advantageous in advancing these efforts.
The nomenclature for Ansky derives from its association with an observable outburst designated ZTF19acnskyy, which was witnessed in visible light back in 2019. This event occurred in a galaxy approximately 300 million light-years away within the confines of the Virgo constellation, serving as the initial harbinger of the peculiar phenomena at play. This visible light outburst ignited further investigations, culminating in the detailed study of Ansky’s properties and behaviors that followed.
Central to the narrative surrounding QPEs is a leading hypothesis suggesting that these eruptions manifest under conditions where a relatively low-mass stellar object intersects the extensive disk of gas that envelops a supermassive black hole. This supermassive entity is known to possess a mass ranging from hundreds of thousands to billions of times that of our Sun, endowing it with a gravitational grip capable of influencing the trajectory of passing objects. When the low-mass intruder pierces the gravitational field of the gas disk, it expels expanding clouds of hot gas, which we detect as the dramatic X-ray flares of QPEs.
The quasi-periodic nature of these eruptions is believed to stem from the gravitational interactions between the smaller object and the supermassive black hole, compounded by the non-circular, spiraling orbits of these smaller bodies as they gradually descend into the gravitational well of the black hole. This dynamic interplay creates a complex cosmic dance where the gravitational pull warps the properties of space-time, preventing the orbits from returning to their original configurations after each cycle.
Lorena Hernández-García, an astrophysicist affiliated with the Millennium Nucleus focusing on Transversal Research and Technology related to Supermassive Black Holes, posits that Ansky’s extreme characteristics could be attributable to the distinctive nature of the gas disk surrounding its associated black hole. In most QPE sources, the outcome of such interactions typically involves the disintegration of a passing star, which subsequently forms a closely orbiting disk around the black hole. In contrast, Ansky’s broader disk appears to interact with a different set of parameters, allowing for a unique interaction involving objects from comparatively greater distances, extending the eruption intervals we observe.
The findings related to Ansky’s properties were detailed in a paper authored by Chakraborty and published in The Astrophysical Journal. The research team employed data collected from NICER, along with simultaneous observations from various other observatories. The deployment of NICER on the International Space Station facilitated frequency observations of Ansky, which proved essential in identifying the fluctuations associated with its X-ray outbursts. Continuous scrutiny from May to July 2024 revealed insights that elucidate the mechanisms governing QPE phenomena.
Chakraborty’s research utilized the precise capabilities of the NICER telescope and XMM-Newton to examine the rapid evolution of the material ejected during QPEs, establishing an unprecedented level of detail regarding the processes in action. By analyzing variations in X-ray intensity during these eruptions, the research team was able to quantify the mass expelled during each event, contemplating the entity’s expansion velocities that approached approximately 15% of the speed of light—a remarkable feat in astrophysical terms.
The relative rarity of NICER’s capacity to gather continuous data on Ansky after the observatory experienced a significant ‘light leak’ in May 2023—since repaired—exemplifies the importance of such observational technology within astrophysical research. Despite encountering obstructions with its observational strategy, NICER has continued to make invaluable contributions to the study of QPEs and other dynamic cosmic phenomena.
Astrophysicists, including Hernández-García, are keenly interested in tracking the temporal evolution of Ansky’s outbursts, with ongoing studies already under review. The results from these observational analyses will serve pivotal roles in preparing the scientific community for a forthcoming era of multimessenger astronomy, integrating varied forms of measurement, from electromagnetic radiation to gravitational waves, for a more comprehensive understanding of cosmic events.
One of the significant goals of the European Space Agency’s LISA mission, co-developed with NASA, is to observe extreme mass-ratio inspirals involving low-mass and supermassive objects akin to Ansky’s environment. Given the expected emissions of gravitational waves emitted from such systems, current electromagnetic studies of QPEs will enhance theoretical models, paving the way for LISA to effectively gather spectral data upon its anticipated launch in the mid-2030s.
Chakraborty expressed excitement at the continued investigation of Ansky and the growing body of research surrounding QPEs. He noted, “We’re still in the infancy of understanding QPEs. It’s such an exciting time because there’s so much to learn.” The journey of exploration into these cosmic eruptions is far from over; instead, it represents a burgeoning frontier in astrophysics that could redefine our comprehension of black holes and the interactions that govern their realms.
Subject of Research: Quasi-Periodic Eruptions near Supermassive Black Holes
Article Title: Rapidly varying ionization features in a Quasi-periodic Eruption: a homologous expansion model for the spectroscopic evolution
News Publication Date: 6-May-2025
Web References: Astrophysical Journal DOI
References: The Astrophysical Journal
Image Credits: Sloan Digital Sky Survey
Keywords
Quasi-Periodic Eruptions, Supermassive Black Holes, NICER, X-ray Outbursts, Ansky, Astrophysics, Multimessenger Astronomy, Gravitational Waves, LISA Mission, Cosmic Phenomena, Black Hole Interactions, Astrophysical Research.
