Katie Mack @AstroKatie (a.k.a. Dr Katherine J Mack) astrophysicist/cosmologist, occasional freelance science writer, connoisseur of cosmic catastrophes Apr. 10, 2019 2 min read

First ever direct image of a black hole! The supermassive black hole in the galaxy M87 -- 6.5 billion times as massive as the Sun! #EHT #BlackHole The image is better than I expected!

How was this image created? A giant global network of radio/millimeter-wave telescopes joined together to create a virtual PLANET-SIZED telescope. The image is patched together from the data from all of these. #EHT #BlackHole (image: Akiyama et al and ApJL)

There's a brief write-up at @PhysicsWorld here:  https://physicsworld.com/a/first-images-of-a-black-hole-unveiled-by-astronomers-in-landmark-discovery/  with more images. Here's the image seen (left) compared with a simulation (middle) and the simulation blurred to the expected resolution of the telescope (right). (Image via Akiyama et al & ApJL)

When will we see a similar image of Sagittarius A*, our own Milky Way Galaxy's supermassive black hole? Hopefully soon... they're still working on the data.

With this image & associated data, we can learn about the nature of the giant black holes at the centers of galaxies. So far, looking at this one, we can say that it’s NOT a wormhole or a boson star, but other alternative hypotheses need more data to be ruled out. #EHT #BlackHole

A sense of scale: the #BlackHole seen here is 6.5 billion times the mass of the Sun, but 55 million light years away. So the image is tiny: the “shadow” seen here is about 40 micro-arcseconds across from this vantage point; a full moon looks tens of millions of times larger.

If you want to dig into why the image looks the way it does, and what we're actually seeing, I have some suggested links for you! See next couple tweets.

Here's a page talking about creating simulated #BlackHole images:  http://rantonels.github.io/starless/  Note: these renderings don't include the effect that makes the part of the disk moving toward us brighter (neither did the film Interstellar -- more about that here  https://arxiv.org/pdf/1502.03808.pdf )

Here's a paper talking about the history of black hole images, with a detailed discussion of what you should expect for the "shadow" image we've just seen. Check Fig 12, with renderings of shadows for disks at different angles  https://arxiv.org/pdf/1902.11196.pdf 

Here's a technical paper from the @ehtelescope team talking about why the ring looks the way it does. Figure 1 showing the comparison between the image and the simulations is especially cool!  https://iopscience.iop.org/article/10.3847/2041-8213/ab0f43 

You can follow @AstroKatie.


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