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Cosmologists ponder the puzzle of black rings
Forget black holes, astronomers are now pondering the properties of black rings
www.technologyreview.com/blog/...23481/
But the discovery in the last 20 years that the universe is not only expanding but accelerating away from us changes all that. If the rings can be created on the scale of the cosmological constant, which causes this accelerated expansion, then various groups have calculated that perhaps this accelerated expansion can balance the gravitational collapse, making black rings stable.
Now Masashi Kimura at Osaka City University in Japan has looked at the possibility of black rings forming in higher dimensional space. It turns out that not only are black rings possible in these conditions, but various other shapes should be stable too.
Kimura's analysis looks at how a thin black ring may have formed early in the Universe's history and later shrunk into a conventional singularity. He also looks at multi black rings--Olympic-style--and describes how these coalesce.
This and other work marks an interesting new branch of theory for black hole specialists. But cosmologists have yet to address the most important questions of all. If these objects do exist or have existed in the past, what would they look like and how might we spot them?
Dynamical Black Rings with a Positive Cosmological Constant
arxiv.org/PS_cache/arxi...904.4311v2.pdf
(Dated: May 2, 2009)
Abstract
We construct dynamical black ring solutions in the five dimensional Einstein-Maxwell system
with a positive cosmological constant and investigate the geometrical structure. The solutions
describe the physical process such that a thin black ring at early time shrinks and changes into
a single black hole as time increase. We also discuss the multi-black rings and the coalescence of
them.
Forget black holes, astronomers are now pondering the properties of black rings
www.technologyreview.com/blog/...23481/
But the discovery in the last 20 years that the universe is not only expanding but accelerating away from us changes all that. If the rings can be created on the scale of the cosmological constant, which causes this accelerated expansion, then various groups have calculated that perhaps this accelerated expansion can balance the gravitational collapse, making black rings stable.
Now Masashi Kimura at Osaka City University in Japan has looked at the possibility of black rings forming in higher dimensional space. It turns out that not only are black rings possible in these conditions, but various other shapes should be stable too.
Kimura's analysis looks at how a thin black ring may have formed early in the Universe's history and later shrunk into a conventional singularity. He also looks at multi black rings--Olympic-style--and describes how these coalesce.
This and other work marks an interesting new branch of theory for black hole specialists. But cosmologists have yet to address the most important questions of all. If these objects do exist or have existed in the past, what would they look like and how might we spot them?
Dynamical Black Rings with a Positive Cosmological Constant
arxiv.org/PS_cache/arxi...904.4311v2.pdf
(Dated: May 2, 2009)
Abstract
We construct dynamical black ring solutions in the five dimensional Einstein-Maxwell system
with a positive cosmological constant and investigate the geometrical structure. The solutions
describe the physical process such that a thin black ring at early time shrinks and changes into
a single black hole as time increase. We also discuss the multi-black rings and the coalescence of
them.
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