AN international team of scientists has produced an image that shows both the ring-like structure that reveals matter falling into the central black hole and the powerful relativistic jet in the prominent radio galaxy Messier 87.
The team, which included Dr Juan Carlos from the Faculty of Science Universiti Malaya, has, in a first, fused new millimetre-wavelength observations to generate the image.
The image underlines for the first time the connection between the accretion flow near the central supermassive black hole and the origin of the jet.
The new observations were obtained with the Global Millimetre VLBI Array (GMVA), complemented by the phased Atacama Large Millimetre/submillimetre Array (ALMA) and the Greenland Telescope (GLT).
The addition of these two observatories has greatly enhanced the imaging capabilities of the GMVA. The results are published in the current issue of Nature.
According to Dr Juan Carlos, "It's like taking a picture of a lit match stick in a very dark room: with the 2019 image, we were able to zoom in to reveal the flame structure.
"By zooming out in a very smart way and preparing the camera with its best settings, we were able to see not only the outer dimmer layers of the flame, but also revealed the smoke coming out from the flame.
"We achieved this by including a set of powerful antennas into the existing array.
"When you see the smoke from a match stick fire or a candle, you may ask where it is coming from. Perhaps from the wick? Or maybe from the inner whitish, or the outer redder part of the flame?
"We had the same question about the origin of the powerful jet in M87. With these observations, now we can peek, for the first time, where the jet emanates from, and answer this question,” he said.
"Previously we had seen both the black hole and the jet in separate images, but now we have taken a panoramic picture of the black hole together with its jet at a new wavelength”, says Ru-Sen Lu, from the Shanghai Astronomical Observatory and leader of a Max Planck Research Group at the Chinese Academy of Sciences.
"The ring that we have seen before is becoming larger and thicker at 3.5 mm observing wavelength. This shows that the material falling into the black hole produces additional emission that is now observed in the new image.
"This gives us a more complete view of the physical processes acting near the black hole," he added.
The participation of ALMA and GLT in the GMVA observations and the resulting increase in resolution and sensitivity of this intercontinental network of telescopes has made it possible to image the ring-like structure in M87 for the first time at the wavelength of 3.5mm.
The diameter of the ring measured by the GMVA is 64 microarcseconds, which corresponds to the size of a small (5 inch/13cm) selfie ring light as seen by an astronaut on the Moon looking back at Earth.
This diameter is 50% larger than what was seen in observations by the Event Horizon Telescope at 1.3 mm, in accordance with the expectations for the emission from relativistic plasma in this region.
"With the greatly improved imaging capabilities of adding ALMA and GLT into GMVA observations, we have gained a new perspective.
"We do indeed see the triple-ridged jet that we knew about from earlier VLBI observations,” says Thomas Krichbaum from the Max Planck Institute for Radio Astronomy (MPIfR) in Bonn.
"But now we can see how the jet emerges from the emission ring around the central supermassive black hole and we can measure the ring diameter also at another (longer) wavelength.”
The light from M87 is produced by the interplay between highly energetic electrons and magnetic fields, a phenomenon called synchrotron radiation.
The new observations, at a wavelength of 3.5 mm, reveal more details about the location and energy of these electrons. They also tell us something about the nature of the black hole itself: it is not very hungry.
It consumes matter at a low rate, converting only a small fraction of it into radiation.
Keiichi Asada of Academia Sinica, Institute of Astronomy and Astrophysics explains: "To understand the physical origin of the bigger and thicker ring, we had to use computer simulations to test different scenarios.
"As a result, we concluded that the larger extent of the ring is associated with the accretion flow.”
Kazuhiro Hada from the National Astronomical Observatory of Japan adds: "We also find something surprising in our data: the radiation from the inner region close to the black hole is broader than we expected.
"This could mean that there is more than just gas falling in. There could also be a wind blowing out, causing turbulence and chaos around the black hole.”
The quest to learn more about Messier 87 is not over, as further observations and a fleet of powerful telescopes continue to unlock its secrets.
“Future observations at millimetre wavelengths will study the time evolution of the M87 black hole and provide a poly-chromatic view of the black hole with multiple colour images in radio light," says Jongho Park of the Korea Astronomy and Space Science Institute. – The Vibes, April 28, 2023
