Wednesday, July 24, 2024

That famous black hole just got darker

Four years ago, astronomers published the first image of a black hole: a red, puffy donut of light surrounding the hollow, dark hole at the center of the giant galaxy M87, located 55 million light-years away in the Virgo galaxy.

The image revealed what astronomers and we could only imagine: a celestial body so massive that its gravity warped spacetime, pulling matter, energy, and even light into its bottomless vortex. This image was released on April 10, 2019 by an astronomical team called the Event Horizon Telescope, so named for the boundary that does not orbit the black hole.

Now a subset of that team, led by Leah Medeiros of the Institute for Advanced Study in Princeton, NJ, has used artificial intelligence to reprocess the original data. A much improved version of the film.

They say the new image will sharpen the constraints on how well the black hole in M87 matches Einstein’s theory of general relativity, which first predicted the existence of black holes. Dr. Medeiros and his colleagues published the new image Thursday in the Astrophysical Journal Letters.

The image may join a 2019 ancestor in the photography collection of the Museum of Modern Art in New York. Both images are based on observations made in April 2017. Using a technique that combined data from five radio telescopes as far away as the South Pole, France, Chile and Hawaii, the Event Horizon team effectively created a telescope as large as Earth. The longest baseline is called interferometry.

The instrument is powerful enough to resolve details as small as an orange or nothing cosmic pin on the surface of a moon 55 million light-years away – the mass of 6.5 billion suns. But gaps in the network led to uncertainty. “We used machine learning to fill in the gaps,” said Dr. Medeiros said in an interview.

His team trained a neural network to identify black holes by feeding them AI simulations of all types of black holes that agree with Einstein’s equations.

Dr Medeiros said that in the improved version, the donut of doom – the visible radiation from the object falling into the hole – is thinner than the original. The empty space at the center of the donut appears black and large, reinforcing the idea that there is indeed a black hole.

The team is already analyzing the new image to get a better estimate of M87’s black hole mass, but they aren’t ready to discuss it yet.

Meanwhile work continues with the even larger Event Horizon network. (Three new telescopes have been added.) Every April, the Earth-sized eye renews its gaze in the darkness when M87 and the center of our galaxy (home to a small black hole) are in view.

“People are in telescopes,” Dr. Medeiros said.

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