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Space

Virtual Telescope Readied To Image Black Hole's 'Ring of Fire' 37

Posted by timothy from the ghost-of-johnny-cash dept.
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."
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Virtual Telescope Readied To Image Black Hole's 'Ring of Fire' More

Virtual Telescope Readied To Image Black Hole's 'Ring of Fire'

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  • Quick note (Score:5, Informative)

    by Arkh89 ( 2870391 ) on Thursday April 23, 2015 @02:20PM (#49539791)

    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...

    • Re: (Score:2)

      by tibit ( 1762298 )

      I think that it'd be doable in the visible spectrum, except that each pixel at the camera would need to be an optical-to-RF heterodyne. You could distribute the phase reference through an optical fiber link.

      • Re:Quick note (Score:5, Informative)

        by Arkh89 ( 2870391 ) on Thursday April 23, 2015 @04:21PM (#49540751)

        Nope, you need the reference phase to still be coherent with the observed object (temporal and spatial), so the interference is only possible between two parts of the same wave (of light), different in space (think two pinholes in a plane through which you collect the light) and/or in time (think delay line, let one part of the line you collected run a longer distance). The first is the famous Young's double slit experiment, the second is the Michelson interferometer.

        Also, for reference : frequency of the visible EM fields is in the order of 300THz (300,000GHz).

  • Interstellar (Score:2, Interesting)

    by pr0t0 ( 216378 )

    We should be able to directly image the spaghettification [wikipedia.org] of Matthew McConaughey's bad acting!

  • By the Goatse Guy?

  • Ring of Fire? Not Sphere of Fire? (Score:3)

    by pz ( 113803 ) on Thursday April 23, 2015 @06:55PM (#49541819) Journal

    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?

    • Because all the standard depictions of accretion disks are art, not real depictions.

  • ..., California, Chile, Mexico, Spain.

    There's got to be a Mexican food angle in there somewhere.

    • Re: (Score:2)

      by Beriaru ( 954082 )
      Not sure about the rest of the places, but it's easier to find good mexican food in New York than in any city of Spain.

  • It spans the whole Earth, from Arizona to the South Pole. I wonder what the Canadians have to say about that comment?

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