Astronomers using the European Southern Observatory’s Very Large Telescope have tracked the binary black hole system Swift J1727.8−1613 through a 2023 eruption, discovering that black holes expel vast amounts of matter through winds and jets even after feeding frenzies subside, challenging the view that they act as simple bottomless pits.
Observing Swift J1727.8−1613 Through a 2023 Outburst
Black holes are rarely witnessed directly because they blend into the dark background of space. Instead, astronomers typically spot them when they violently consume nearby celestial objects, such as stars. When this happens, instruments register the light of the star being pulled into the gravity well.
To investigate this phase, an international team of researchers led by the University of Warwick focused on the binary system Swift J1727.8−1613. When the system erupted in 2023, it became one of the brightest X-ray sources in the sky over Earth. Rather than relying on isolated snapshots, researchers utilized the European Southern Observatory’s Very Large Telescope to capture multiple observations over time, assembling a detailed optical record of the outburst from start to finish.
How Accretion Disks Feed Black Holes and Trigger Ejections
The material pulled away from the companion star cannot fall straight into the black hole because it possesses rotation, or angular momentum. Instead, the gas forms a swirling structure known as an accretion disk. The immense gravitational pull of the central object generates friction and intense tidal forces within this disk, superheating the gas and causing it to glow brightly.
As the black hole fed on the star, it simultaneously discharged high-speed plasma jets and powerful winds back into space. The observations showed that the accretion disk underwent major changes precisely when the system launched these powerful jets, offering a clear view of how cosmic titans process their meals.
Rethinking Inefficient Eaters and Cosmic Indigestion
The central revelation of the study centers on what happens after the feeding frenzy. Conventional models often treat black holes as endless gluttons that swallow everything in their path. However, the data from Swift J1727.8−1613 indicate that these systems function more like complex digestive units that expel a surprising proportion of what they pull in.
“People often imagine black holes simply swallowing everything around them, what we’re seeing is a much more complex process. Matter falls in, the system processes it, and a surprising amount is expelled again.”
Photo: Universetoday
Dr. Noel Castro Segura, Postdoctoral Fellow at the University of Warwick
Even more surprising was the persistence of these outflows. Researchers estimate that the total mass flung back into space may ultimately equal the amount consumed by the black hole itself, meaning half of the stellar meal never actually reached the maw.
“We usually gravitate towards the dramatic fireworks when a black hole outburst begins, but our observations show that the finale can be just as intense.”
Kyle Solomons, Doctoral Researcher at the University of Cape Town
Implications for Binary Star Evolution
These findings, published on July 29 in the Monthly Notices of the Royal Astronomical Society, offer new perspectives on how binary star systems evolve over cosmic timescales. According to the research team, systems like Swift J1727.8−1613 likely began as a pair of stars where the more massive companion eventually exhausted its fuel and ended its life in a supernova, leaving behind the black hole observed today.
6 Astronomers Just Captured a Black Hole Eating a Star
By demonstrating that black holes are less efficient eaters than previously assumed, the observations provide a clearer picture of how these cosmic systems shape their surrounding environments long after their brightest outbursts fade.
