Astronomers have just released the first-ever image of the area near the event horizon of Sagittarius A*, the 4.3 million solar mass black hole at the heart of our galaxy.
Sagittarius A*
The black holes are notoriously difficult to observe, since light itself cannot escape their extreme gravitational pull. It is however possible to distinguish their outlines thanks to the enormous quantities of gas and dust which they attract, forming a accretion disk shining around them.
To image Sgr A*which is regarding 27,000 light-years from the Terrethe researchers relied on data from the virtual telescope Event Horizon, connecting eight radio observatories around the world. The object was closely observed over several nights (the team likening this process to using a long exposure time on a camera).
Detailed in the review Astrophysical Journal Lettersthis major breakthrough comes just over three years following the same collaboration published the first direct image of a black holelying at the heart of the giant elliptical galaxy Messier 87regarding 55 million light-years away.
A closer but significantly harder to image black hole
If the two objects have striking visual similarities, Sgr A* turns out to be more than a thousand times smaller than M87* and also less massive (4.3 million solar masses once morest 6.5 billion for the latter), which made the realization of its first direct image much more difficult than that of M87yet much further from the Terre.
« The gas moves at the same speed – almost as fast as light – around Sgr A* and M87, but while it takes days or even weeks to orbit the latter, it only needs a few minutes to do it around Sgr A* “, Explain Chi-kwan Chancooperation EHT.
« This means that the brightness and gas configuration around Sgr A* was changing rapidly as the EHT collaboration observed it – much like trying to take a sharp shot of a puppy trying to grab its tail. turning on itself “, he adds.
Major implications
Closely matching the predictions of the general relativity theoryEinsteinthese observations offer new insights into how giant black holes interact with their environment.
« Although they are in two distinct types of galaxies and also have very different masses, the edges of these two cosmic monsters turn out to be very similar. “, Explain Sera Markoffof the’university of amsterdam.
« This tells us that general relativity rules these objects up close, and that any differences we observe farther away must be due to differences in the matter surrounding the black holes. “, she concludes.