A supermassive black hole dormant for decades has just awakened in a distant galaxy. This sudden activation provides a unique opportunity to study the behavior of these cosmic giants in real time.
Located 300 million light-years away, the galaxy SDSS1335+0728 hosts a black hole named Ansky at its center. After a long period of inactivity, it began emitting X-ray flashes of unprecedented intensity. The first glows were detected in late 2019, marking the beginning of a series of unprecedented observations.
Artist's impression of the accretion disk around black hole Ansky and its interaction with a small celestial object.
Credit: European Space Agency
Researchers used several space telescopes, including ESA's XMM-Newton and NASA's Swift, to track Ansky's evolution. Data reveals quasi-periodic eruptions (QPEs) of exceptional energy and duration. These still poorly understood phenomena could challenge current models of matter accretion by black holes.
The international team, led by Lorena Hernández-García, published their findings in
Nature Astronomy. Observations suggest Ansky didn't destroy a star to form its accretion disk. Instead, surrounding gas might be directly feeding the black hole, causing energetic shocks responsible for the X-ray flashes.
Ansky's eruptions are ten times longer and brighter than those observed elsewhere. Their approximately 4.5-day periodicity challenges current explanations. Team member Joheen Chakraborty emphasizes these extreme characteristics are pushing theoretical models to their limits.
This study opens new perspectives on QPE formation and their connection to gravitational waves. ESA's LISA mission, planned for the 2030s, could detect these waves and complement X-ray observations. Erwan Quintin, an astronomer at ESA, stresses the importance of this data for understanding black hole behavior.
Ansky continues to be closely monitored by astronomers. Its evolution could reveal still unknown mechanisms of black hole activity. This discovery reminds us that the Universe still harbors phenomena capable of surprising even the most experienced scientists.
What is a quasi-periodic eruption (QPE)?
QPEs are X-ray flashes emitted at regular intervals by certain black holes. These events remain largely mysterious. They might result from interaction between a small celestial object and a black hole's accretion disk.
QPEs typically last a few hours and repeat every few days or weeks. However, Ansky shows eruptions ten times longer and more energetic, suggesting different mechanisms. Researchers consider shocks in the accretion disk or gravitational disturbances.
Studying these phenomena could illuminate black hole dynamics and their environment. QPEs might also be linked to gravitational waves, offering a new way to study the Universe.
How can a black hole 'wake up'?
An inactive black hole can activate when it begins absorbing matter. This process forms an accretion disk where heated gas emits intense radiation. In Ansky's case, activation appears due to capturing surrounding gas rather than destroying a star.
Supermassive black holes like Ansky can alternate between active and dormant phases over varying timescales. These transitions depend on matter availability for absorption. Observing a live awakening is rare and valuable for understanding these cycles.
Scientists use X-ray telescopes to track these changes. Ansky's data could reveal how black holes influence their host galaxies and how they evolve over time.