New data from Webb shows the Milky Way’s central supermassive black hole flares multiple times per day
The magnetic field lines surrounding Sagittarius A*,
published in March 2024. Click for original image.
Though past research had shown that the Milky Way’s central supermassive black hole, dubbed Sagittarius A* (pronounced A-star) is generally quiet and inactive, new data from the Webb Space Telescope gathered over a year’s time now shows that it flares multiple times per day.
Throughout the year, the team saw how the black hole’s accretion disk emitted 5 to 6 large flares per day, of varying lengths and brightnesses, plus smaller flares in between. “[Sagittarius A*] is always bubbling with activity and never seems to reach a steady state,” Yusef-Zadeh says. “We observed the black hole multiple times throughout 2023 and 2024, and we noticed changes in every observation. We saw something different each time, which is really remarkable. Nothing ever stayed the same.”
In their paper published in The Astrophysical Journal Letters, the team outlines two possible ideas for the processes driving these flares. The faint flickers may be caused by turbulent fluctuations in the accretion disk, which could compress plasma and trigger a burst of radiation. “It’s similar to how the sun’s magnetic field gathers together, compresses and then erupts a solar flare,” Yusef-Zadeh says. “Of course, the processes are more dramatic because the environment around a black hole is much more energetic and much more extreme.”
The larger and brighter flares, on the other hand, may be caused by two fast-moving magnetic fields colliding and releasing accelerated particles. These magnetic reconnection events also have a solar parallel.
You can read their paper here [pdf]. Though this research shows unexpected activity, that activity is still relatively mild compared to other central supermassive black holes in many other galaxies. Why this difference exists remains an unanswered question.
The magnetic field lines surrounding Sagittarius A*,
published in March 2024. Click for original image.
Though past research had shown that the Milky Way’s central supermassive black hole, dubbed Sagittarius A* (pronounced A-star) is generally quiet and inactive, new data from the Webb Space Telescope gathered over a year’s time now shows that it flares multiple times per day.
Throughout the year, the team saw how the black hole’s accretion disk emitted 5 to 6 large flares per day, of varying lengths and brightnesses, plus smaller flares in between. “[Sagittarius A*] is always bubbling with activity and never seems to reach a steady state,” Yusef-Zadeh says. “We observed the black hole multiple times throughout 2023 and 2024, and we noticed changes in every observation. We saw something different each time, which is really remarkable. Nothing ever stayed the same.”
In their paper published in The Astrophysical Journal Letters, the team outlines two possible ideas for the processes driving these flares. The faint flickers may be caused by turbulent fluctuations in the accretion disk, which could compress plasma and trigger a burst of radiation. “It’s similar to how the sun’s magnetic field gathers together, compresses and then erupts a solar flare,” Yusef-Zadeh says. “Of course, the processes are more dramatic because the environment around a black hole is much more energetic and much more extreme.”
The larger and brighter flares, on the other hand, may be caused by two fast-moving magnetic fields colliding and releasing accelerated particles. These magnetic reconnection events also have a solar parallel.
You can read their paper here [pdf]. Though this research shows unexpected activity, that activity is still relatively mild compared to other central supermassive black holes in many other galaxies. Why this difference exists remains an unanswered question.
