From NASA via Science Alert: “This NASA Visualisation of a Black Hole Is So Beautiful, We Could Cry”

From NASA

via

ScienceAlert

Science Alert

26 JAN 2020
MICHELLE STARR

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NASA Visualization Shows a Black Hole’s Warped World

The first-ever direct image of a black hole’s event horizon was a truly impressive feat of scientific ingenuity. But it was extremely difficult to achieve, and the resulting image was relatively low-resolution.

Mesier 87*, The first image of a black hole. First-ever direct image of a black hole, Messier 87*. (EHT Collaboration).This is the supermassive black hole at the center of the galaxy Messier 87. Image via JPL/ Event Horizon Telescope Collaboration.

EHT map

Now iconic image of Katie Bouman-Harvard Smithsonian Astrophysical Observatory after the image of Messier 87 was achieved. Headed from Harvard to Caltech as an Assistant Professor. On the committee for the next iteration of the EHT .

Techniques and technology will be refined, and it’s expected that future direct images of black holes will improve with time. In September 2019, a NASA visualisation – made for the agency’s Black Hole Week – showed what we might expect to see in high-resolution images of an actively accreting supermassive black hole.

Supermassive black holes sit at the centres of most large galaxies, and how they got there is a mystery; which came first, the black hole or the galaxy, is one of the big questions in cosmology.

What we do know is that they are really huge, as in millions or billions of times the mass of the Sun; that they can control star formation; that when they wake up and start feeding, they can become the brightest objects in the Universe. Over the decades, we have also figured out some of their strange dynamics.

In fact, the very first simulated image of a black hole, calculated using a 1960s punch card IBM 7040 computer and plotted by hand by French astrophysicist Jean-Pierre Luminet in 1978, still looks a lot like NASA’s simulation.

In both simulations (the one above, and Luminet’s work below), you see a black circle in the centre. That’s the event horizon, the point at which electromagnetic radiation – light, radio waves, X-rays and so forth – are no longer fast enough to achieve escape velocity from the black hole’s gravitational pull.

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(Jean-Pierre Luminet)

Across the middle of the black hole is the front of the disc of material that is swirling around the black hole, like water into a drain. It generates such intense radiation through friction that we can detect this part with our telescopes – that’s what you are seeing in the picture of Messier 87*.

You can see the photon ring, a perfect ring of light around the event horizon. And you can see a broad sweep of light around the black hole. That light is actually coming from the part of the accretion disc behind the black hole; but the gravity is so intense, even outside the event horizon, that it warps spacetime and bends the path of light around the black hole.

You can also see that one side of the accretion disc is brighter than the other. This effect is called relativistic beaming, and it’s caused by the rotation of the disc. The part of the disc that is moving towards us is brighter because it is moving close to light-speed. This motion produces a change in frequency in the wavelength of the light. It’s called the Doppler effect.

The side that’s moving away from us, therefore, is dimmer, because that motion has the opposite effect.

“It is precisely this strong asymmetry of apparent luminosity,” Luminet wrote in a paper last year, “that is the main signature of a black hole, the only celestial object able to give the internal regions of an accretion disk a speed of rotation close to the speed of light and to induce a very strong Doppler effect.”

Simulations such as these can help us understand the extreme physics around supermassive black holes – and that helps us understand what we are seeing when we look at the picture of Messier 87*.

See the full article here .

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The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs. NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.