Two years ago, astronomers got the first direct image of a black hole. A coordinated campaign of observation of this object now adds to our understanding of this black hole and its tumultuous environment.
Located in the core of elliptical galaxy M87, this supermassive black hole carries the mass of 6.5 billion suns. In April 2019, the Event Horizon Telescope (EHT) Collaboration will have a direct image of this object, in what was an unparalleled achievement for astronomers.
Our understanding of the M87 black hole has taken a quantum leap forward thanks to an extensive multi-wavelength observation campaign of the object, the details of which now appear in Astrophysical Journal Letters. This colossal campaign took place from April to March 2017 and involved 760 scientists from nearly 200 institutions around the world.
“This incredible array of observations includes many of the world’s best telescopes,” said Juan Carlos Algaba, an astronomer from the University of Malaya in Kuala Lumpur, Malaysia, in a NASA JPL. press release“This is a wonderful example of astronomers around the world working together in the pursuit of science.”
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A total of 19 different observatories were used during the campaign, including the Hubble Space Telescope, Chandra X-ray Observatory, the Neil Gehrels Swift Observatory and the Fermi Gamma-ray Space Telescope. Together, these observatories have scanned the entire electromagnetic spectrum and offered observations of the M87 black hole in radio waves, visible light, X-rays and gamma rays.
“We knew the first direct image of a black hole would be groundbreaking,” Kazuhiro Hada, a co-author of the study and an astronomer at the National Astronomical Observatory of Japan, said in the NASA publication. “But to get the most out of this remarkable image, we need to know all about the black hole’s behavior at the time by observing across the entire electromagnetic spectrum.”
An accompanying video shows the power of this multi-wavelength approach. The video starts with the now iconic image of the M87’s black hole and slowly zooms back to highlight the whole spectacle in context. The scale is given in light years and each observatory is given credit for its specific contribution. Side-by-side comparisons are also shown, revealing images of the black hole as depicted in radio waves, visible light and X-rays. The last part of the video shows the black hole and its beam in gamma rays, as viewed by the Fermi telescope.
The high-speed jet is a prominent feature of these and many other supermassive black holes. These jets are the result of enormous gravitational forces involved, and they move at speeds approaching that of light.
These jets produce different light intensities across the spectrum, and scientists want to study the complex patterns within them, as they are an indication of the black hole’s spin, energy output, and other properties. But this is not an easy task as these variables are constantly changing over time. The new research, through the Coordinated Campaign, was an attempt to overcome this limitation and capture a multi-wavelength snapshot of the black hole using data captured by all of these observatories at roughly the same time. Indeed, this is now the “largest simultaneous observation campaign ever undertaken on a supermassive black hole with jets,” NASA said.
The results could improve the tests of Einstein’s general theory of relativity and provide a better understanding of the jets and their possible association with cosmic rays.
“Understanding particle acceleration is really central to our understanding of both the EHT image and the jets, in all their ‘colors,'” said Sera Markoff, a co-author of the study and an astronomer from the University of Amsterdam. in the press release. “These jets manage to transport the energy released by the black hole to a shell larger than the host galaxy, like a huge power cord. Our results will help us calculate the amount of force carried and the effect the black hole’s jets have on its environment. “
More observations are needed, but the good news is that the EHT has started a new observation campaign this week. Excitingly, 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 likely be unavailable for a while, but we can’t wait to see the outcome, including how the M87 black hole has changed over the past four years.
More: In March 2021, astronomers first captured an image of the magnetic field lines of the M87 black hole.