A relatively frequent black hole absorbs a star when it is too close to it, but a team of astronomers surprised to find that one of them is still exploding the remains of star material almost three years after swallowing her "food." This phenomenon is for the first time, and discovery can help to better understand the events of the tide break.
This is followed by a particularly intense electromagnetic radiation, followed by extended star matter turning around a black hole, heating up and creating a flash of light that astronomers can easily see from a distance of millions of light years.
One such TDE, called AT2018hyz, occurred in October 2018, about 665 million light-years away from Earth, but radio data recorded by a very large array in New Mexico, showed that the black hole mysteriously came to life in June 2021, almost three years after the event. "
The black hole suddenly began to shine, although it did not absorb any other objects during that time.
In exceptional cases, the team was able to take advantage of immediate observation time on several telescopes to study this unusual phenomenon. They were able to collect data in several ranges of VLA wave lengths, the ALMA observatory in Chile, MeerKAT in South Africa, the Australian Telescope Compact Array, and the Chandra and Swift Space Observatorys.
"," researchers write in The Astrophysical Journal. The optical, ultraviolet and X-ray observations of TDE usually track the decay of star mass and accretion, and radio observations detect the release of a substance released into space. When a star spaghetts, part of its material is actually sometimes thrown back into space.
This is the first time that researchers have seen such a long delay. " — Edo Berger, professor of astronomy at Harvard University and co-author of the study.
The event of AT2018hyz seemed normal when it was first observed in 2018. "," says Sebastian Gomez, a post-doctor of the Space Telescope Science Institute and co-author of the study. However, the data collected at the time made it possible to estimate the mass of the sun's sunken star: it was only one tenth of the mass of our sun.
The outflow usually occurs shortly after TDE, rather than years later, as observed by AT2018hyz. ", summarized by the team.
"," says Cendes. This material flow is not only incredibly late, but much faster than usual: the team calculated that the material was moving at 50% of the speed of light.
The team does not yet know why this flow of matter has been delayed for several years, but offers several possible explanations. First, this sudden delay in activity may be the result of a change in the status of the accretion disk. Another explanation is that the original magnetic field of the sunken star should not contain a magnetic field strong enough for a relativist jet; the necessary magnetic field could only be created later, via an alternative source. Finally, it is possible that the relativist jet was present at the beginning of TDE but could not pass through a cloud of gas and debris that was particularly dense at the beginning of the event.
The next step will be to determine whether this phenomenon occurs more regularly; perhaps astronomers simply did not observe TDE long enough to notice it...