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Virtual Telescope Readied To Image Black Hole's 'Ring of Fire'
astroengine writes: With the addition of a telescope at the southern-most point of Earth, the Event Horizon Telescope (EHT) now spans the diameter of our planet and, when the vast project goes online, astronomers will get their first glimpse of the bright ring surrounding a supermassive black hole. Using a method known as Very Long Baseline Interferometry, or VLBI, astronomers can combine the observing power of many telescopes situated at distant locations around the planet. The distance between those observatories, known as the "baseline," then mimics a virtual telescope of that diameter. Now, in an attempt to make direct observations of the supermassive black hole in the center of our galaxy, located at a powerful radio emission source called Sagittarius A*, the South Pole Telescope (SPT) at the National Science Foundation's Amundsen-Scott South Pole Station has been linked to the EHT and the stage is set for a historic new era of exploring the most extreme objects in the known universe. "Now that we've done VLBI with the SPT, the Event Horizon Telescope really does span the whole Earth, from the Submillimeter Telescope on Mount Graham in Arizona, to California, Hawaii, Chile, Mexico, Spain and the South Pole," said Dan Marrone of the University of Arizona. "The baselines to SPT give us two to three times more resolution than our past arrays, which is absolutely crucial to the goals of the EHT. To verify the existence of an event horizon, the 'edge' of a black hole, and more generally to test Einstein's theory of general relativity, we need a very detailed picture of a black hole. With the full EHT, we should be able to do this."
This telescope operate in the radio bands (sub-millimeter) and not in the visible. That's why it is easy to make interferometry over very long base line. In the visible domain this is very tricky to realize over a couple of 100m (such as with the VLTI).
You can think of it as completing piece by piece the Fourier transform of the image you want to observe. Every pair of telescope gives you a measurement in the so-called UV plane (spatial frequencies). The furthest the observations point are (the telescopes) the smaller details you can get. Except this is only valid if you can measure the amplitude and phase of the electromagnetic radiation (or find a way to reconstruct it in some way). This is easy in the radio bands. But this oscillation is just too fast with visible wavelength and thus, we can not record and adjust offline, we have to interfere the waves right away...
We should be able to directly image the spaghettification of Matthew McConaughey's bad acting!
I'm sorry, but your opinion seems to be wrong.
Anons should not be aloud to post until at least 10 registered users have commented.
Some things need to be said...
By the Goatse Guy?
Truth isn't Truth - Guliani
I'm not an astrophysicist. I'm not even a physicist. I never took quantum mechanics. I don't understand GR, and many of the often-discussed effects completely baffle me. But given that accretion disks are, you know, BIG, why do all of the standard depictions I see of black holes make them look black? Shouldn't the accretion disk, spewing tons of energy as it heats up on the death spiral, obscure the black hole? Black holes -- at least ones like at Saggitarius A -- have huge accretion disks, much, much bigger than the event horizon. So won't it just look like a fuzzy bright area?
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
There's got to be a Mexican food angle in there somewhere.
Have gnu, will travel.
Because not all black holes feeding all the time.
Black hole in the center of our galaxy is not very active.
It spans the whole Earth, from Arizona to the South Pole. I wonder what the Canadians have to say about that comment?
You almost answered yourself, just think about it: accretion *disk*. That's it. All the fun happens in a flat, ring-like structure. Imagine Saturn, but with huge very bright rings and an absolutely black centre. That's what we expect to see.
The movie "Gravity" actually went to some care to depict their black hole correctly. See the picture here. The ring passing horizontally across the front of the black hole is the accretion disk. The ring *around* the black hole is the far side of the accretion disk, gravitationally lensed around the black hole.
Yeah, this is the stuff of dreams, and nightmares. Before we absolutely accept there's a blackhole at the centre of our galaxy, can be disprove other theories that make a lot more sense, and don't contradict the laws of physics? (Such as the Electric Universe theory). Black holes are talked of as if they are a reality that is not questioned. But nothing could be further from the truth. People still say Einstein predicted it, but he didn't, and never agreed that you could ever make the tensor RIC = 0. It is this very mathematical thought, and an ignorance of gravity being intrinsic to matter, and therefore you can't ever get 0 in there. Yet the 0 became a black hole, and we think we can see them in space. But can we? PZ is right to be confused by all the jargon and contradiction surrounding black holes - because they don't conform to the laws of physics. Until we actually understand what gravity is, we can't hope to make sense of all this. So we have these fanciful ideas with billions of dollars behind them so we can look at the stars, and tell others what we think we see. But it's because like a game of Chinese whispers, and we're at the end of the chain, listening to messages that don't make sense, and are far removed from the source.
You mean "Interstellar".
Don't fornicate. Seriously, just don't do it.
Does Saggitarius A* actually have an accretion disk? It shouldn't as long as nothing is falling in.
and never agreed that you could ever make the tensor RIC = 0. It is this very mathematical thought, and an ignorance of gravity being intrinsic to matter, and therefore you can't ever get 0 in there. Yet the 0 became a black hole, and we think we can see them in space.
What the heck are you talking about? The Ricci tensor is zero in any vacuum solution, and this applies to a large number of things other than than black holes, including gravity around stars and planets (something verified to quite high levels of precision), and also how you can reduce GR to SR. This applies to any solution outside of the source of gravity, whether it is a ball of gas, a planet, or a black hole, and it isn't something special to black holes, and is of course something Einstein was aware of since it forms the basis of a lot of initial predictions and statements about GR.
It is an x-ray source, which is part of how it was discovered. There is always "something" falling in, but it doesn't have to be a large amount of material.
Whatever. I don't go to movies, there are too many attractive and easy-going people there. They all seem to know how to fit in while I'm embarassed by my own awkwardness. I can't even go to see "Star Trek" movies because there's a crowd of good-looking people in the theatre now. There used to be only folks like me once. The place I can go become fewer and fewer. What can I do?
Because all the standard depictions of accretion disks are art, not real depictions.
I do accept that an actual blackhole that sucks in information and doesn't let it leave probably does not exist, but the generation notation of a crazy dense object that mostly redshifts the heck out of light and can grow to be really large, does exist. When you see a 100M solar mass object orbiting a 18bil solar mass objects at 1/3rd the speed of light, but themselves emit nearly no light, most people would describe that as a "blackhole".
The reason your standard depictions make them look black is because those depictions are wrong. They're an artist's conception and you'll note that most artists are not mathematicians or astrophysicists. Kip Thorne from CalTech worked with the staff doing CGI simulations for the black hole in the movie Interstellar to help them get the math right. Specifically, he helped them get the gravitational lensing working properly in their simulations. What they came up with is extraordinary and beautiful, and is the most realistic (from our best mathematical models) black hole every seen by human eyes. Someone else referenced the Wired article on this process, but I'll repost it here: http://www.wired.com/2014/10/astrophysics-interstellar-black-hole/
To answer your other questions, yes the accretion disk will heat up and spew light (and other energy) as it spins. However, due to the physics of rotating gravity wells, the object itself will not be completely obscured due to the fact that the matter is being forced into a disk surrounding it (like the rings of Saturn). However, the rings of Saturn are only subject to moderate gravitational lensing, thus they look like rings when you view them from any angle. The ring around a black hole is subject to extreme lensing effects, which causes the parts of it at the "sides" and "back" (from your perspective if looking at it at or near the plane of the accretion disk) to warp around the black hole in a sort of halo effect.
Combine that with the fact that space itself is warping and you'll definitely get a fuzzy, glowing halo and disk around the thing, but you'll still get that dark center as well. All of this comes together with a beauty only nature can master. You can see a quick version of all this here: https://www.youtube.com/watch?v=iu7QDQPMq3Y
Is there any telescope in orbit that could be added as a node? What types of discoveries could be made if a node on the Moon was added? Mars?