Posted on 01/12/2008 3:29:53 PM PST by LibWhacker
[...snip...]
But on to antimatter, a cloud of which has been known to exist around the galactic center since the 1970s, when balloon-based gamma-ray detectors first located it. Gamma rays are significant in terms of antimatter because electrons encountering positrons (their antimatter equivalent) annihilate each other, with their mass converted into high energy gamma rays. So the cloud’s presence is well established. The question since its detection is what could have caused it.
Now a new paper in Nature may offer an answer, noting the asymmetric distribution of the antimatter cloud, which extends further on one side of galactic center than on the other. We’re talking about a cloud some 10,000 light years across, generating the energy of 10,000 Suns. The research team used data from the European Space Agency’s Integral satellite (INTErnational Gamma-Ray Astrophysics Laboratory) to detect the asymmetry. Their paper notes that it matches the distribution of a certain type of binary star systems, the latter thought to contain neutron stars and black holes.
Image: Integral mapped the glow of 511 keV gamma rays from electron-positron annihilation.
The map shows the whole sky, with the galactic center in the middle. The emission extends to
the right. Credit: ESA/Integral/MPE/G. Weidenspointner.
Are these binary stars the cause of the antimatter cloud? They’re what’s known as ‘hard’ low-mass X-ray binaries. The mechanism at play is that gas from a low-mass star spirals into a black hole or neutron star nearby, with high-energy (hard) X-rays resulting. That and the relative similarity between the distributions of cloud and stars makes the case that the binaries are producing these interesting positrons. In fact, says lead author Georg Weidenspointer (Max Planck Institute for Extraterrestrial Physics), “Simple estimates suggest that about half and possibly all the antimatter is coming from X-ray binaries.”
Of course, what comes immediately to mind at this end is James Bickford’s interesting work on antimatter collection here in the Solar System. As we saw in several earlier posts, Bickford has been advocating collection strategies that would mine the antimatter being formed naturally not only near the Earth but also in abundance further out in the Solar System, especially around Saturn. So the idea of antimatter farming again comes to the front with this renewed reminder that the exotic stuff occurs as a result of astrophysical processes and not just in particle accelerators.
Not that we’re able to tap a cloud like this one, so vast and so much further from Earth. But on a theoretical level, it’s useful to learn more about antimatter production even while we’re discovering the limitations in our existing theories. For the questions the antimatter cloud poses are themselves vast. The low-mass binaries seem associated with the antimatter cloud but we lack knowledge of how they could produce enough positrons to account for it. That probably targets particle jets as the necessary area for investigation, something NASA’s GLAST (Gamma-ray Large Area Space Telescope) may be able to shed further light on. And GLAST is helpfully ready for a 2008 launch.
The paper is Weidenspointner et al., “An asymmetric distribution of positrons in the Galactic disk revealed by big gamma-rays,” Nature 451 (10 January 2008), pp. 159-162 (abstract).
Ping
How long before Bush gets the blame for this?
0.2 milliseconds if it can be linked to “global warming.”
bkmarking this for later. Thank you, sir.
The map shows the whole sky, with the galactic center in the middle.
Okay, dumb question - what galaxy? 'The Whole Sky' is more than our galaxy, the Milky Way. I read and searched the entire article and it doesn't clarify???
Or am I missing something? (wouldn't be the 1st time, nor last)
We must send Hillary to check it out.
But if it's antimatter, it shouldn't matter at all.
Not a dumb question. It’s a map in the gamma ray part of the EM spectrum. So visible light isn’t shown. The whole sky is represented as a globe (notice it goes from 90-degrees North to -90-degrees South, and 360-degrees latitudinally). What it shows is the shape and extent, or size, of the region of gamma ray emissions in our galaxy relative to the entire sky, with the Milky Way centered. There are other gamma-ray sources out there, of course. Don’t know why they chose not to represent at least a few of them on the map.
Hillary will come back with a study which shows that first responders to this crisis were subjected to matter-antimatter annihilation disappearance syndrome (with a little burst of Gamma radiation thrown in for good measure), and that Bush and the entire Republican party were at fault for their negligence in not securing the galactic center fast enough. Lawsuits will follow. Hillary will shed a tear for the fallen matter particles and win the White House with strong support from the anti-matter coalition ........
The Dec issue of Astronomy magazine has an interesting article about some non symmetry of the background microwave radiation that might indicate something such as that it is not way out there at the edge of the universe but right here in the solar system. Or not, but it’s another question about the universe, which is not turning out to be at all what has been expected.
Someday (with proper shielding) they may get inside the cloud, but may not like what they find...
Wouldn't it be a big kick in the butt that a lot of what we think we know about the CMB is bogus. Me thinks there is a good chance that the small variations seen in the CMB are caused by local influences (solar system neighborhood) rather than cosmic. Many a theory (universe flat and not opened or closed, etc, etc) based on CMB interpretations may be fixing to fall.
And it has no effect and the SUV is still the cause of global warming.
Fascinating. BMFLR.
ping
Thanks, I didn't think I was misreading the article.
**** There are other gamma-ray sources out there, of course. *****
That's for sure, like the Super Gamma Ray Bursts 'recently found' at the 'edges' of the (known) Universe. Not sure If I buy how 'they' twisted the findings to fit into E=mc2. When I saw it on the Science Channel I really had to chuckle. With normal logic (and laws of physics) SGRBs blow E=mc2 to hell.
"Curiously enough, the only thing that went through the mind of the bowl of petunias as it fell was Oh no, not again. Many people have speculated that if we knew exactly why the bowl of petunias had thought that we would know a lot more about the nature of the universe than we do now."
Little did he know how accurate that was going to be!
Cheers!
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