Astronomers have observed unprecedented X-ray flashes and unusual behavior from the supermassive black hole 1ES 1927+654, located approximately 270 million light-years away in the constellation Draco. In 2023, the activity of this black hole increased significantly, associated with a prolonged increase in low-energy X-rays that resulted in new radio flares, according to Gazeta.ru.
By April 2023, a team led by Sibasish Laha at the University of Maryland, Baltimore County (UMBC) and NASA's Goddard Space Flight Center in Greenbelt, Maryland, noted a steady, months-long increase in low-energy X-rays from the black hole, reported Phys.org. This surge in X-rays prompted the team to initiate new radio observations.
The observations revealed features never before seen in real time around a supermassive black hole. Among them was the launch of a plasma jet moving at nearly one-third the speed of light. Eileen Meyer, a professor at UMBC and co-author of the study, noted, "The launch of a black hole jet has never been observed before in real time," as reported by Phys.org.
The team employed the National Radio Astronomy Observatory's (NRAO) Very Long Baseline Array (VLBA) to conduct intensive observations. The VLBA is a network of radio telescopes spread across the United States, combining signals from individual dishes to create a powerful, high-resolution radio camera. This array allowed astronomers to detect features less than a light-year across at the distance of 1ES 1927+654.
This marks the first-ever measurement of its kind around a supermassive black hole. Monitoring of the black hole continues, including observations from NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) and the European Space Agency's XMM-Newton mission.
Astronomers have long puzzled over why only a fraction of supermassive black holes produce powerful plasma jets. Studying the plasma ejections from 1ES 1927+654 may provide valuable insights into how these jets are formed.
The increased activity in 1ES 1927+654 has been observed not only in X-rays but also in radio waves. Radio data from 2023 revealed jets of ionized gas, or plasma, extending from either side of the black hole.
This unusual behavior follows the black hole's intriguing activity observed in 2018. At that time, astronomers noted that the corona—a billion-degree cloud of rapidly moving particles surrounding the black hole—suddenly vanished during a tidal disruption event and reappeared months later.
Since then, scientists have been closely monitoring 1ES 1927+654. Members of the Massachusetts Institute of Technology (MIT) team have detected additional unprecedented behavior from the black hole.
Megan Masterson, a doctoral candidate at MIT who co-led the discovery, has been studying the black hole's unusual X-ray flares. The team observed that the interval between X-ray flashes from 1ES 1927+654 shortened dramatically from once every 18 minutes to every seven minutes over two years.
Masterson and her colleagues explored various models to explain the X-ray patterns observed. One hypothesis suggests that a low-mass white dwarf star, about as large as Earth, is orbiting perilously close to the black hole's event horizon. This white dwarf may be shedding its dense outer layers as it interacts with the black hole's accretion disk, triggering the observed X-ray pulses.
If this scenario is accurate, the white dwarf is performing an extraordinary balancing act, hovering just a few million miles from the event horizon without being consumed.
Erin Kara, an associate professor of physics at MIT, explained, "These things are really small and quite compact, and we hypothesize that it's a white dwarf that is getting so close to the black hole," as reported by Semana. She added, "Because these stellar remnants are so small and compact, they are difficult to tear apart; thus, they can come very close to a black hole without being destroyed," as noted by Mashable.
This interaction could be producing gravitational waves in a frequency range detectable by future space-based observatories, such as the European Space Agency's Laser Interferometer Space Antenna (LISA), expected to launch in the 2030s. "If a white dwarf is indeed the cause...it would also emit gravitational waves in a range that could be detected by next-generation observatories like NASA's Laser Interferometer Space Antenna (LISA)," according to Phys.org. Astronomers are particularly excited to study the system once LISA is operational.
The behavior of 1ES 1927+654 challenges existing models of black hole activity and provides a unique opportunity to study extreme astrophysical phenomena.
This article was written in collaboration with generative AI company Alchemiq