, 10 tweets, 6 min read Read on Twitter
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! A glowing ring, brighter on the bottom, with a dark region in the middle
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) Globe with six telescope sites labelled and with lines drawn between them. Acronyms on image: JCMT, SMA, SMT, LMT, PV, APEX, ALMA, SPT.
There's a brief write-up at @PhysicsWorld here: physicsworld.com/a/first-images… 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) Blurry image as seen, left. (It looks like a fuzzy bright donut.) Center has a swirly sharp image with a bright ring and a dark hole in the middle, with a label of the scale showing 40 micro-arcseconds. Then on the right is the simulation image blurred so that it looks pretty much exactly like the observed image.
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: 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 arxiv.org/pdf/1502.03808…)
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 arxiv.org/pdf/1902.11196… A bunch of simulated images with disks at different angles relative to the line of sight. Top left is a super thin disk completely edge-on -- it just looks like a thin circle brighter on the right. Then there are a range of them that look like smooshed disks with a bright bit on one side. And at the lower left, there's one fully face-on, with uniform brightness around the circle (but brighter at the shadow edge)
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! iopscience.iop.org/article/10.384… The image seen by the telescope (a blurry ring of light with the bottom half much brighter and thicker than the top half, and the middle of the ring dark), then a simulation that looks like a bright thin ring with wispy bits coming out around it and a very dark center, and then a simulation that's blurred to match the telescope resolution that looks exactly like the telescope image.
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