A supermassive black hole roars to life as astronomers watch in real time

In December 2019, astronomers were surprised to observe a long-quiet galaxy, 300 million light-years away, suddenly come alive, emitting ultraviolet, optical and infrared radiation into space. Far from calm again, by February of this year, the galaxy began emitting X-ray light; It has become more active. Astronomers believe it is most likely Active galactic nucleus (AGN), which gets its energy from supermassive black holes at the center of the galaxy and/or from the black hole's rotation. This is conclusion A New paper It has been accepted for publication in the journal Astronomy & Astrophysics, although the authors acknowledge the possibility that it may also be a type of rare tidal disturbance event (TDE).

The brightness of SDSS1335_0728 in the constellation Virgo, after decades of quiescence, has been detected for the first time by the Zwicky Transient Facility telescope. The mass of its supermassive black hole is estimated at about one million solar masses. To get a better understanding of what might be happening, the authors combed through archival data and combined it with data from new observations from various instruments, including Shooter Xpart of Very large telescope (VLT) in the Atacama Desert in Chile.

There are several reasons why a normally quiet galaxy might suddenly brighten, including supernovas, or TDEs, in which part of the original mass of the violently torn apart star is ejected outward. This in turn can be shaped Accumulation disk About a black hole that emits powerful X-rays and visible light. But these events last no more than five years, and usually no longer than a few hundred days.

So the researchers concluded that the galaxy had woken up and now had active nuclei. First discovered by Karl Seifert in 1943, the glow is the result of cold dust and gas surrounding the black hole, which can form accretion disks orbiting the black hole. Gravitational forces compress the material in the disk and heat it to millions of degrees Kelvin, producing radiation across the electromagnetic spectrum.

Alternatively, this activity may be caused by a particularly long and faint TDE, the longest and weakest yet detected, if so. Or it could be an entirely new phenomenon. So SDSS1335+0728 is a galaxy worth watching. Astronomers are already preparing for follow-up observations with the VLT's Multi-Unit Spectroscopic Explorer (MUSE) and the Extremely Large Telescope, among others, and perhaps even Vera Rubin Observatory It is scheduled to come online next summer. The Large Synoptic Survey Telescope (LSST) will be able to continuously image the entire southern sky, potentially capturing more galaxy awakenings.

“Regardless of the nature of the differences, [this galaxy] It provides valuable information about how black holes grow and evolve. said co-author Paola Sanchez SaezAstronomer at the European Southern Observatory in Germany. “We expect such tools [these] The key will be in understanding [why the galaxy is brightening]”.

There is also a supermassive black hole at the center of our Milky Way Galaxy (Sgr A*), but there is not yet enough material accreted for astronomers to be able to pick up any radiation emitted, even in the infrared. Therefore, its galactic core is considered inactive. It may have been active in the past, and it is possible that it will awaken again in a few million (or even billions) of years when the Milky Way Galaxy merges with the Andromeda Galaxy and their supermassive black holes combine. Only so much time will tell.

Astronomy and Astrophysics, 2024. DOI: 10.1051/0004-6361/202347957 (About digital IDs).

Listing image by ESO/M. Kornmesser