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For those wondering if we could get sharper images with JWST, here’s the previously imaged black hole (same angular size as our own) compared to a single pixel
by wthomp 4y ago
For those wondering if we could get sharper images with JWST, here’s the previously imaged black hole (same angular size as our own) compared to a single pixel from Hubble’s wide field camera 3:
https://twitter.com/alex_parker/status/1116070667068170240?s=21&t=5NM9DEiOYb8U3LVWFI6otw https://twitter.com/alex_parker/status/1116070667068170240?s...
JWST will have smaller “pixels” but is in the same ballpark.
- hammock 4y agoHow sharp do we expect an infinite-res picture to be?
- fsh 4y agoThe resolution of these telescopes is limited by diffraction, not by the number of pixels on the sensors. The achievable angular resolution is roughly the wavelength divided by the aperture diameter [1]. JWST works in the few µm wavelength range and has a 6.5 m aperture, such that the angular resolution is ~0.1 arcsec. The EHT works with 1.3 mm wavelength and has an effective aperture of roughly the earth diameter (~13000 km). This leads to an angular resolution of a few ten µarcsec which is more than 1000 times higher than that of JWST. [1] https://en.wikipedia.org/wiki/Angular_resolution https://en.wikipedia.org/wiki/Angular_resolution
- amelius 4y agoCan we invert the diffraction process numerically?
- adgjlsfhk1 4y agono
- fsh 4y agoNo, this is fundamentally impossible. There are infinitely many possible objects that would produce the same blurry image.
- deleted 4y ago[deleted]
- amelius 4y agoI think you just sort of rephrased the question :) Also, if you have a photo of a tree, then there are infinitely many objects that will produce that photo; however, that doesn't make it a bad or worthless photo. But I suppose you could be right for a single image from one angle, and I suppose that we don't get to see this particular object from many different angles.
- marricks 4y agoThen why did we build the JWST! /s
- hammock 4y agoShould have clarified. Does a black hole have fuzzy edges or sharp edges?
- dekhn 4y agothis is sort of getting into the definition of black holes and event horizons. I don't think they really have solid surfaces, I would expect all imaging here to show fuzzy samples.
- hammock 4y agoLike, would it be a gradient from dense-to-fuzzy as you move outward from the center, until you reach the event horizon outside of which is nothing?
- dekhn 4y agoI couldn't really say for sure but I think macroscopically (viewed from a low-resolution telescope) it would look fuzzy, but close up, it would look very spiky and dynamic with all sorts of stochastic events happening.
- ISL 4y agoThe edge should be quite sharp. Any deformation or movement in the edge will be smoothed extremely quickly, on timescales comparable to the light-crossing time of the object -- in this case ten seconds or so. If you're a photon and you're in, you stay in. If you're out and heading out, you get out. (if you skim the surface, you might make an orbit and then leave :) ). It is that fact that makes the edge quite sharp.
- sandworm101 4y agoI disagree. The edge of a BH is essentially an asymptote. While there is a mathematical bright line, when looking at it you should see light in all manner of red/blue-shifted colors near the event horizon. Since that light is coming in from a variety of directions it leaves in a variety of directions too. Everything would look soft and fuzzy around the edges. Out of focus.
- sam-2727 4y agoWhile it won't be able to image more sharply on its own, JWST can still help to constrain certain factors in their modeling, thus obtaining better images. See, e.g., https://www.stsci.edu/jwst/phase2-public/2235.pdf https://www.stsci.edu/jwst/phase2-public/2235.pdf (although this was written when there was no image, certainly it would still be useful).
- MeteorMarc 4y agoAnd here you see the new picture compared with the 2019 picture of Messier 87: https://blackholecam.org/ https://blackholecam.org/
- belter 4y agoSimilar comparison in size. "Size comparison of the two EHT black holes": https://youtu.be/UOESt-G34vE https://youtu.be/UOESt-G34vE
- SkyMarshal 4y agoSo you’re saying no, JWST won’t provide significantly sharper images of black holes than the Event Horizon Telescope?
- deleted 4y ago[deleted]
- hbrav 4y agoJWST would be unable to resolve the black hole at all.
- sandworm101 4y agoJWST is nowhere near the caliber of telescopes necessary to resolve black holes. Very literally, we would need an optical telescope bigger than new york city to even make an attempt.
- chrsw 4y agoWhat about an array of space telescopes creating a kind of "virtual lens"? Putting aside the engineering scale and cost of such a project, would something like that even be possible? Or would that be pure science fiction?
- terramex 4y agoIt is possible in principle, but gets harder as wavelength of captured light gets smaller and so far it is done only for long radio waves on planet scale. https://en.wikipedia.org/wiki/Astronomical_optical_interferometry https://en.wikipedia.org/wiki/Astronomical_optical_interfero... https://en.wikipedia.org/wiki/Aperture_synthesis https://en.wikipedia.org/wiki/Aperture_synthesis
- ugh123 4y agoThis is what the Event Horizon telescope does https://en.wikipedia.org/wiki/Event_Horizon_Telescope https://en.wikipedia.org/wiki/Event_Horizon_Telescope
- 4y ago
- wnevets 4y agoThat really puts the significance of this new image into perspective.
- guelo 4y agoThere is so much post processing that the telescope resolution barely matters. Personally I'm skeptical of these images since the algorithms have a lot of data fitting to "what it should look like" built in to them.
- boringg 4y agoHow much post processing is happening? This isn't raw co-ordinated but rather fit data?
- agar 4y agoIs the EHT "only" planet scale, or is it taking a second measurement 180 days later to increase the effective diameter of the virtual antennae to the width of the earth's orbit?
- wthomp 4y agoNo, unfortunately those measurements have to be taken at the same time. That said, as the Earth rotates the distance between any two pairs of antennas changes which can be used to add additional information to the images (those new pairs of measurements again have to be taken simultaneously). From what I understand, this is less useful for looking at Sgr A* since the scene isn’t static and changes on a roughly 10 minute timescale.
- dillondoyle 4y agoThat's incredible science and engineering. The Reddit ask science thread said it would be akin to taking a photo of a donut on the moon. So impressive even if off by a lot.
- buzzard1 4y ago
- kristopolous 4y agoThat's in the article actually
- wolfram74 4y agoWhen a research group comes up with a useful/good enough metaphor/analogy they will use it over and over again.
- codethief 4y agoNo wonder one of the questions in the Q&A session at yesterday's NSF press conference went like this: Journalist: Why is the image so blurry? Answer by one of the panelists: It's actually one of the sharpest images I've ever taken.