View Full Version : Cosmic String Detected?

2004-Jun-22, 02:58 PM
Cosmic Strings [as opposed to the tiny strings thought to account for sub-atomic particles] would be huge massive gravitationally radiating dark objects. They have been hypothesized as part of several types of grand unified theories. They appear as defects in space-time. They would have formed about the same time as Quarks started freezing out.

Until now, there has been no direct evidence of them that has been noticed. Here is a paper about observations of a lensed Quasar that shows signs of a cosmic string briefly [a year or two] passing between us, and the lensing galaxy.
smoking gun of a cosmic string? (http://www.arxiv.org/PS_cache/astro-ph/pdf/0406/0406434.pdf)

Note that some other explanations are possible, but are mostly ruled out for practical reasons. [for example, it could be explained by a pair of co-orbiting intermediate-mass blackholes on the line between us and the quasar about 4 lightyears from us].

John L
2004-Jun-22, 03:38 PM
They seem to cover a few possible alternative explanations, but the math is a little above my head, and are we sure that they covered all other possible explanations? It would great if they can prove that this event was caused by a string, as it would end some of the myriad of theories, and lend new support to others.

2004-Jun-22, 04:33 PM
Originally posted by John L@Jun 22 2004, 03:38 PM
are we sure that they covered all other possible explanations?
I had some trouble with the math too, as well as the theory behind the cosmic string's continued existence. For me, this was kind of like Price's statement that he'd observed a magnetic monopole. Finding a cosmic string seems pretty unlikely. Still, all that we can do is keep building more and better equipment, and do more observing while we wait for another such opportunity. Next time someone will be on the lookout, and get some time with the best tools out there. At the very least there is something odd out there in that general direction offering a new opportunity to test some theory or another.

2004-Jun-22, 05:36 PM
It would sure be cool though, if that is what they hope. Like John says, it would really put some constraints on the theories.

Nice find anton :)

2004-Jun-23, 12:26 PM
Here's another paper by the same guy [Schild at Harvard] writing about the microlensing events from the same lensed quasar. In this paper he is proposing that the universe is filled with planet sized objects that were formed shortly after the plasma cooled to atoms [380,000 years after the big bang by the WMAP scale].
The Detection and Nature of the Baryonic Dark Matter (http://www.arxiv.org/PS_cache/astro-ph/pdf/0406/0406491.pdf)
Note that Baryonic Dark Matter is not the mysterious dark matter that requires weakly interacting particles, but is the normal matter made of protons, neutrons, electrons, etc that is not luminous.

2004-Jun-23, 12:33 PM
Here's a paper explaining Cosmic Strings.
B − L Cosmic strings and Baryogenesis (http://www.arxiv.org/PS_cache/hep-ph/pdf/0406/0406054.pdf)