Long-held theories on how black holes like the one at the centre of our galaxy, the Milky Way, evolve were proven right this week thanks to research made possible by Canadian scientists.听
A team of researchers from the University of 蓝莓视频 and Perimeter Institute听who are members of the global Event Horizon Telescope (EHT) collaboration, developed a powerful framework called that processes the EHT data, generating clear and accurate images that cut through noise and identify what really exists just outside the鈥痓lack hole.听
While the first photos of the Sagittarius鈥疉* (Sgr A*) black hole were unveiled in 2022, the new images revealed its plasma ring, but also the magnetic field lines that shape and organize it.听听
鈥淪gr A* is like a frenetic toddler,鈥� said Dr. Avery Broderick, a professor at the University of 蓝莓视频鈥檚 Department of Physics and Astronomy and associate faculty at Perimeter Institute. 鈥淲e鈥檙e seeing for the first time the invisible structure that shepherds the material within the black hole鈥檚 disk and drives plasma to the event horizon, helping it to grow.鈥澨�
Side-by-side comparison of the magnetic fields around the black hole at the centre of the M87 galaxy (left) and the Sgr A* black hole at the centre of our galaxy, the Milky Way.听
THEMIS 鈥� led by Broderick and his team 鈥� assessed the credibility of any given image of the black hole by providing a reliable statistical method for studying the information Sgr A* sends us from across the galaxy. It also can image black holes like Sgr A* even though they refuse to sit still thanks to swirling plasma, which is constantly churning away over short timescales.听听
That can be modelled by THEMIS to provide an estimate for the 鈥渘oise鈥� in the data, which can be averaged out to produce a clear, time-averaged image of Sgr A* in spite of its rapid variability.听
The researchers鈥� results reveal strong polarization patterns in the signals that Sgr A* emits. Polarization 鈥� a property describing the orientation of light wave oscillations 鈥� is the same principle that sunglasses use to eliminate glare in multiple directions. By measuring the polarization, scientists are able to measure the structure and strength of Sgr A*鈥檚 magnetic fields.听
鈥淭he polarized light we see from Sgr A* is striking,鈥� Broderick said. 鈥淣ot only is it highly polarized, at three times more polarization than the black hole at the centre of the M87 galaxy, but it鈥檚 also highly organized. This new image limits the density of the plasma orbiting Sgr A* and reveals the magnetic fields that govern its fate.鈥澨�
According to astronomers鈥� best models of black hole evolution, the magnetic fields in the accretion disk need to be strong enough to push the accreting plasma around. The new results from Sgr A* (and those from its much larger cousin M87* previously) provide the first direct observational evidence to support those models.听听
This new research marks a milestone in black hole astronomy, helping to tell the story of black hole evolution and bring the unruly core of our galactic neighbourhood into sharp focus.
This research was presented in two papers by the EHT collaboration published on Wednesday, March 27 in The Astrophysical Journal Letters: "" and "".听
