A ‘glowing’ bubble of gas circles the Milky Way’s giant black hole at breakneck speed

On May 12, 2022, the very first image of the central black hole in our galaxy, Sagittarius A*, was revealed. Scientists have since continued their studies of this supermassive star. And by observing data from the Alma radio telescope, they made a surprising discovery: a bubble of glowing gas is orbiting the black hole at 30% of the speed of light! How to explain it?

On May 12, 2022, the very first image of our central black hole was taken GalaxyGalaxy was revealed byEvent Horizon Telescope (EHT). Sagittarius A* was visible for the first time along with its accretion diskaccretion disk. Opportunity to learn more about this supermassive black holesupermassive black hole almost 4 billion solar masses! Located in the heart of The Milky WayThe Milky Wayto 27,000 light yearslight years from Earth, Sagittarius A* will have given scientists difficulties: five years of hard work were needed to put it into the picture. The observations on which it is based actually date from 2017 and were carried out by a network of eight radio telescopes, includingAtacama Large Millimeter/submillimeter Array (Alma), located at the European Southern Observatory (ESOESO) in Chile.

But after imaging it, scientists used Alma’s observations to infer the properties of our black hole and its environment. And luckily for them, they discovered a strange phenomenon there, detailed in a study by Astronomy and astrophysics : a hotspothotspot orbiting at high speed around Sagittarius A*! “We think we are looking at a gas bubble incandescent lampincandescent lamp glides around Sagittarius A* on a orbitorbit similar in size to that of the planet MercuryMercury, but does a full lap in only about 70 minutes. This requires an astonishing speed of about 30% of the speed of lightthe speed of light ! », enthused Maciek Wielgus in a press release from ESO, first author of the study and astronomerastronomer to Max Planck Institute for RadioRadio astronomy in Bonn, Germany.

The supermassive black hole Sagittarius A*, imaged by the Event Horizon Telescope Collaboration (EHT), along with an artist’s impression of the location of the hotspot and its orbit around the black hole, based on modeling forecast data from Alma. © EHT Collaboration, ESO, M. Kornmesser, M. Wielgus

An eruption of Sagittarius A* ejected a bubble of plasma…

According to the study, this hot spot finds its explanation in the eruption of black holes. The observations used by the researchers actually dated both April 6 and 7, 2017, and April 11, 2017. However, an eruption of the black hole Sagittarius A * occurred just before these last observations, which were detected in them X-raysX-rays talk space telescopespace telescope Chandra. The data collected by the researchers, curves of polarized light, then changed, and they interpreted them as the generation of a hot spot spinning at high speed around the black hole. Because the change of the curve of polarized light indicates a change of magnetic fieldsmagnetic fields around the black hole.

And for scientists, this is proof that everything is played by magnetic fields! “Now we find evidence solidsolid for a magnetic origin of these eruptions, and our observations give us a clue about the geometry of the process. The new data are extremely useful in constructing a theoretical interpretation of these events.” explains Monika Mościbrodzka, co-author of the study and astronomer at Radboud University. These black hole eruptions are similar to those taking place on our surface starstarthat SunSunat the origin of polar northern lightspolar northern lights.

In the case of a black hole gasgas hot which orbits very rapidly around it forms an accretion disc. Within the disk is fabricfabric is so heated to millions of degrees that it changes to plasma, therefore to ionized and magnetized gas. Due to extreme temperature conditions, pressurepressure, speed prevailing in the disc, different magnetic fields are generated which interact with each other and twist. When these fields meet, they can reconnect or reconfigure, leading to what is called magnetic reconnection. A part ofenergyenergy accumulated before reconnection then ejected, whether in the form of X-rays, heatheator even directly from fabric. And that’s what the researchers observed: a bubble of glowing gas,” circling clockwise in an inner region of the accretion flow”describes the study.

that was so cool! And the researchers saw that.

Finally, these observations testify to a new phenomenon coming from the eruptions, which is hitherto unknown: the cooling of the plasma jets emitted by this eruption, which remain in orbit around the black hole. “What is really new and interesting is that such flare-ups have so far only been clearly present in X-rays and infraredinfrared of Sagittarius A*. Here we see for the first time a very strong indication that orbiting hotspots are also present in radio observations.” explains Maciek Wielgus.

Because the fact that this gas bubble was observed in radio waves indicates a fairly low temperature, these waves are much less energetic than X-rays or infrared. “Perhaps these hot spots detected under infrared waves are a manifestation of the same physical phenomenon: as soon as the hot spots emitted in the infrared cool, they become visible in wavelengthswavelengths longer, like those observed by Alma and EHT”, adds Jesse Vos, study co-author and PhD student at Radboud University in the Netherlands. Subsequently, the researchers intend to focus even more on this phenomenon, especially through observations with the EHT. “Hopefully one day we will be able to claim that we ‘know’ what is going on in Sagittarius A*”concludes Maciek Wielgus.

Leave a Comment