Two years ago, astronomers acquired the first direct image of a black hole. A coordinated campaign to observe this object now adds to our understanding of this black hole and its tumultuous surroundings.
Located in the core of the elliptical galaxy M87, this supermassive black hole has a mass of 6.5 billion suns. In April 2019, the Collaboration Event Horizon Telescope (EHT) launched a direct image of this object, in what was an unparalleled achievement for astronomers.
Our understanding of the M87 black hole has taken a major leap forward thanks to an extended multi-wavelength observation campaign of the object, Details of which now appear in the Astrophysical Journal Letters. This colossal campaign took place from April to March 2017 and involved 760 scientists from almost 200 institutions around the world.
“This incredible set of observations includes many of the best telescopes in the world,” Juan Carlos Algaba, an astronomer at the University of Malaya in Kuala Lumpur, Malaysia, told NASA JPL Press release. “This is a wonderful example of astronomers around the world working together in search of science.”
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A total of 19 different observatories were used during the campaign, including the Hubble Space Telescope, the Chandra X-ray Observatory, the Neil Gehrels Swift Observatory and the Fermi Gamma Space Telescope. Together, these observatories scanned the entire electromagnetic spectrum, providing observations of the M87 black hole in radio waves, visible light, X-rays and gamma rays.
“I knew that the first direct image of a black hole would be revolutionary,” Kazuhiro Hada, co-author of the study and astronomer at the National Astronomical Observatory in Japan, said in a NASA statement. “But to make the most of this remarkable image, we need to know all we can about the behavior of the black hole at that time, observing the entire electromagnetic spectrum.”
An attendant video presents the power of this multi-wavelength approach. The video begins with the now iconic image of the M87 black hole and slowly shrinks to expose the entire show in context. The scale is displayed in light years and each observer receives credit for his special contribution. Side-by-side comparisons are also presented, revealing views of the black hole as imagined in radio waves, visible light and X-rays. The final part of the video shows the black hole and its gamma-ray jet, as seen by the Fermi telescope.
The high-speed jet is a striking feature of this and many other supermassive black holes. These jets are the result of huge gravitational forces involved and move at speeds close to that of light.
These jets produce different intensities of light across the spectrum, and scientists are eager to study the complex patterns in them, as they are indicative of black hole rotation, energy production, and other properties. But this is not a simple task, because these variables change constantly over time. The new research, through its coordinated campaign, was an attempt to overcome this limitation and capture a multi-wavelength snapshot of the black hole using data captured by all these observers at about the same time. And indeed, this is now “the largest simultaneous observation campaign ever undertaken on a supermassive black jet hole,” according to NASA.
The results could improve tests of Einstein’s theory of general relativity and provide a better understanding of jets and their possible association with cosmic rays.
“Understanding particle acceleration is truly central to our understanding of both EHT imaging and jets, in all their ‘colors,'” Sera Markoff, co-author of the study and astronomer at the University of Amsterdam, said in a press release. . “These jets manage to transport the energy released by the black hole to larger scales than the host galaxy, like a huge power cord. Our results will help us calculate the amount of energy transported and the effect of black hole jets on its environment. ”
More comments are needed, but the good news is that EHT has started a new observation campaign this week. Interestingly, the new campaign will be even bigger, as it now includes the Kitt Peak Telescope in Arizona, the NOrthern Extended Millimeter Array (NOEMA) in France and the Greenland Telescope.
The results of the 2021 observation campaign will probably not be available for a while, but we can’t wait to see the result, including how the M87 black hole has changed in the last four years.
Moreover, in March 2021, astronomers first created an image of the magnetic field lines of the M87 black hole.