 |
| Radio images of 1ES 1927+654 reveal emerging plasma jets erupting from the galaxy’s central black hole, first detected in February 2024 after a strong radio flare, with structures expanding about half a light-year from the center. |
International teams of astronomers monitoring a supermassive black hole in the heart of a distant galaxy have discovered previously unseen features using data from NASA missions and other observatories. These findings, including a high-speed plasma jet and rapid X-ray fluctuations, provide new insights into the behavior of black holes and their accretion processes.
The black hole, located in the galaxy 1ES 1927+654 about 270 million light-years away in the constellation Draco, has a mass approximately 1.4 million times that of the Sun. The black hole began exhibiting unusual activity in 2018 with an optical, ultraviolet, and X-ray outburst, which sparked continuous monitoring by various teams, including one led by Eileen Meyer, an associate professor at the University of Maryland Baltimore County (UMBC).
Meyer shared her team's findings at the 245th meeting of the American Astronomical Society, revealing that after the initial outburst, the black hole experienced a period of relative quiet, only to show a steady increase in low-energy X-rays starting in April 2023. This prompted new observations, including those from NASA’s Neil Gehrels Swift Observatory, NICER, and other facilities. The increased X-rays led to the discovery of a strong, unusual radio flare observed with the Very Long Baseline Array (VLBA), a network of radio telescopes across the U.S. The data revealed jets of ionized gas extending about half a light-year from the black hole.
 |
| The active galaxy 1ES 1927+654, located 270 million light-years away, has shown dramatic changes since a major outburst in 2018, with a central black hole weighing 1.4 million solar masses. |
"The launch of a black hole jet has never been observed in real time," Meyer explained. The jet likely began earlier, coinciding with the increase in X-rays before it broke through the surrounding hot gas in early 2024.
In addition to the radio flare, astronomers observed rapid X-ray fluctuations between July 2022 and March 2024. These millihertz quasiperiodic oscillations, where the X-ray brightness fluctuated by 10% every few minutes, suggest the presence of an object orbiting within the black hole's accretion disk. The variations could be caused by an object spiraling closer to the event horizon, emitting gravitational waves that drain its energy and speed up its motion.
Over two years, the fluctuation period decreased from 18 minutes to just 7, signaling that the object was moving at nearly half the speed of light. Surprisingly, the fluctuation period then stabilized, prompting the team to propose a new hypothesis: the object could be a white dwarf—a stellar remnant about the size of Earth—shed some of its mass as it approached the black hole. This model could also explain why the orbital motion stopped, as the white dwarf's loss of mass counteracted the energy loss from gravitational waves.
 |
| In this artist’s concept, a white dwarf orbits within 1ES 1927+654's accretion disk, with its matter stripped away by the supermassive black hole, a scenario explained by rapid X-ray oscillations detected by ESA’s XMM-Newton, to be confirmed by the upcoming LISA mission. |
Masterson, a doctoral candidate at MIT, also noted that this scenario predicts the detection of gravitational waves from the white dwarf’s movement by future missions like the Laser Interferometer Space Antenna (LISA), a collaboration between NASA and the European Space Agency, which will launch in the next decade.
These findings, described in papers in The Astrophysical Journal Letters and the upcoming Nature, could significantly advance our understanding of black hole physics, plasma jets, and accretion processes.
Comments