ALMA Discovers Massive Rotating Disk In Early Universe (phys.org) 33
A reader shares a report from Phys.Org: In our 13.8 billion-year-old universe, most galaxies like our Milky Way form gradually, reaching their large mass relatively late. But a new discovery made with the Atacama Large Millimeter/submillimeter Array (ALMA) of a massive rotating disk galaxy, seen when the universe was only ten percent of its current age, challenges the traditional models of galaxy formation. Galaxy DLA0817g, nicknamed the Wolfe Disk after the late astronomer Arthur M. Wolfe, is the most distant rotating disk galaxy ever observed. The unparalleled power of ALMA made it possible to see this galaxy spinning at 170 miles (272 kilometers) per second, similar to our Milky Way.
The discovery of the Wolfe Disk provides a challenge for many galaxy formation simulations, which predict that massive galaxies at this point in the evolution of the cosmos grew through many mergers of smaller galaxies and hot clumps of gas. In most galaxy formation scenarios, galaxies only start to show a well-formed disk around 6 billion years after the Big Bang. The fact that the astronomers found such a disk galaxy when the universe was only ten percent of its current age, indicates that other growth processes must have dominated. "We think the Wolfe Disk has grown primarily through the steady accretion of cold gas," said J. Xavier Prochaska, of the University of California, Santa Cruz and coauthor of the paper. "Still, one of the questions that remains is how to assemble such a large gas mass while maintaining a relatively stable, rotating disk." "The star formation rate in the Wolfe Disk is at least ten times higher than in our own galaxy," adds Prochaska. "It must be one of the most productive disk galaxies in the early universe."
The findings have been published in the journal Nature.
The discovery of the Wolfe Disk provides a challenge for many galaxy formation simulations, which predict that massive galaxies at this point in the evolution of the cosmos grew through many mergers of smaller galaxies and hot clumps of gas. In most galaxy formation scenarios, galaxies only start to show a well-formed disk around 6 billion years after the Big Bang. The fact that the astronomers found such a disk galaxy when the universe was only ten percent of its current age, indicates that other growth processes must have dominated. "We think the Wolfe Disk has grown primarily through the steady accretion of cold gas," said J. Xavier Prochaska, of the University of California, Santa Cruz and coauthor of the paper. "Still, one of the questions that remains is how to assemble such a large gas mass while maintaining a relatively stable, rotating disk." "The star formation rate in the Wolfe Disk is at least ten times higher than in our own galaxy," adds Prochaska. "It must be one of the most productive disk galaxies in the early universe."
The findings have been published in the journal Nature.
DLC? (Score:1)
You can buy one from the intergalactic app store.
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Aw crap! (Score:1)
Likely scenario (Score:3, Interesting)
Re:Likely scenario (Score:5, Informative)
PS ALMA is pretty fucking awesome, you should read up on it's capabilities.
Yes it is and if this isn't news for nerds, I don't know what is. Here's one of the coolest pictures from the site:
https://en.wikipedia.org/wiki/... [wikipedia.org]
Note the lack of streaking in the sky, so this isn't a very long exposure shot. I'm sure it was taken with a camera with more than 8 bits (HDR, all pro cameras are) and possibly HDR from multiple shots on top of that. Even so, that is how clear the sky is 5000m up in the desert in the middle of nowhere. Astounding!
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I don't know how long the exposure was in this pic, I suppose indeed short, but can't ALMA do the equivalent of a telescope tracking mount to avoid trails?
https://astrobackyard.com/equa... [astrobackyard.com]
If not, how does it capture anything useful at all with long exposure?
Re:Likely scenario (Score:5, Informative)
I don't know how long the exposure was in this pic, I suppose indeed short, but can't ALMA do the equivalent of a telescope tracking mount to avoid trails?
I'm sure it can, but that picture was taken with an optical camera with a wide angle lens (you can tell by the funny stretching towards the image edges it is a low distortion, wide angle lens) on the ground, not a millimeter wave radiotelescope. If the exposure was long and the camera was tracking the sky, then the non sky things (the vehicle) would be streaked instead.
It was really a comment about how astonishingly clear the sky is there (presumably why they put a telescope on that spot).
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Ah, I was being slow. Thank you.
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Yes radio telescopes can track as the earth rotates to take long exposures. In some cases exposures are built up over may days. Some CMB radio telescopes scan the same patch of sky repeatedly for years to improve then intensity and polarization resolution.
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Thanks for another clarification, it was early and I was confused :)
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The person who asks questions is only confused for a short time. The person who doesn't, stays confused.
I work on radio telescope technology development, and how they are able to track as the earth rotates is not at all obvious - for these large arrays it isn't enough to just steer the dishes, you need to take into account the phase shift to each dish as the angle changes. Some radio telescopes (like CHIME) don't physically steer at all, but instead use signal processing from a large number of antennas to
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Yeah I figured that it must be way more complicated for such a huge array than for a single dish on a mount - I was actually aware that those can track :)
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More a reply to my previous post: trailing might probably not matter for deep space observation?
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Note to self: read before posting. Not true
It takes billions of years to form (Score:1)
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So is reading, apparently.
Rotating (Score:4, Interesting)
I wonder why everything in the universe is rotating in the first place. The term "Big Bang" seems to imply that all matter in the universe was flung in all directions from a tiny tiny point, so where does the rotation come from?
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so where does the rotation come from?
The spin is what keeps it everything from collapsing - from atoms to galaxies. You can't answer where the spin comes from without also answering where everything comes from.
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Take an ice skater, hurricane, planet-moon system, or galaxy and there is an explanation for the spin, but ALL the universe's spin? Your observation that spin is part of everything is ridiculously simple yet profoundly true. I wonder, if you add all the rotation would it sum to zero? If it doesn't cancel to zero then what would that say? I bet on zero, but I'd like to find the universe is a spin 1 particle in a mega... something ;-)
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That is a very interesting question. I wonder who can say anything intelligent about it, so we can ask them.
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I adhere to the ancient wisdom of Blood, Sweat and Tears...
"What goes up must go down, spinning wheel got to go round..."
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I think that the total angular momentum of the universe is known to be small, consistent with zero. I don't know what observational limits there are on the total angular momentum, (or even the appropriate units) but it would have a clear signature on the cosmic microwave background.
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The term "Big Bang" seems to imply that all matter in the universe was flung in all directions from a tiny tiny point, so where does the rotation come from?
Thats not how inflation works.
A better analogy is that the tiny point became a giant point.
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Trying to answer the "why" about anything will ultimately degenerate into a circular argument. QED
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I wonder why everything in the universe is rotating in the first place. The term "Big Bang" seems to imply that all matter in the universe was flung in all directions from a tiny tiny point, so where does the rotation come from?
That is easy. The answer is: not dark matter, but other stuff that is not dark matter? [youtube.com]
The tougher question is: What, exactly, is a large millimeter? Is it anything like a centimeter?
I'm waiting for results from the (Score:2)
massively huge enormous gigantic telescope. Is that working yet?
Same sh*t, different day? (Score:2)
To people who say that, I say, "No, you're 14,688,000 miles from where you were yesterday."