Rogue black holes may roam the galaxy
- URL to an interesting article from Fox news
I really like the title. I wonder if there are tame black holes.
Reminds me of the story The Doomsday Effect by TK Wren
First few paragraphs
Hundreds of massive black holes left over from the early universe may
wander the Milky Way, according to new calculations.
These _rogue black holes_
(http://www.space.com/scienceastronomy/080109-aas-rogue-black-holes.html) are thought to have originally lurked at the
centers of tiny, low-mass galaxies. Over billions of years, those dwarf
galaxies smashed together to form full-sized galaxies like the Milky Way.
The idea of such wandering black holes _has been suggested before_
(http://www.space.com/scienceastronomy/astronomy/blackhole_010913.html) , but a new
computer simulation calculated that hundreds of them should be left over,
and predicted that they might now be shrouded by small star clusters.
"These black holes are relics of the Milky Way's past," said researcher
Avi Loeb of the Harvard-Smithsonian Center for Astrophysics. "You could say
that we are archaeologists studying those relics to learn about our galaxy's
history and the formation history of black holes in the early universe."
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It appears that Earth is safe. The closest rogue black hole should reside
thousands of light-years away.
Astronomers are eager to locate them for the clues they will provide about
the formation of the Milky Way, since they are thought to date from the
universe's galaxy-building days.
Back then, whenever two young galaxies with central black holes collided,
their black holes would _merge to form a single black hole_
(http://www.space.com/scienceastronomy/astronomy/blackhole_merges_020208.html) . In the
chaos of the merger, the black hole could be flung out toward the edges of the
galaxy, the new computer model shows.
It predicts that hundreds of such black holes would still be around today
in the _outer reaches of the Milky Way_
(http://www.space.com/scienceastronomy/070524_wandering_bhole.html) , each containing the mass of 1,000 to
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They would be difficult to spot on their own, though, because a black hole
is not visible. They can be detected, however, when matter they're about
to swallow is superheated as it accelerates inward.
Another telltale sign could mark a rogue black hole: a surrounding cluster
of stars yanked from the dwarf galaxy when the black hole escaped. Only
the stars closest to the black hole would be tugged along, so the cluster
would be very compact.
These clusters are so small that each looks like a single star from far
away. Thus, astronomers will have to use tricks to distinguish them, such as
separating the light from the clusters into its component colors to
discover the individual stars hiding inside.
"The surrounding star cluster acts much like a lighthouse that pinpoints a
dangerous reef," said Harvard-Smithsonian Center for Astrophysics' Ryan
O'Leary, who co-wrote the paper. "Without the shining stars to guide our way,
the black holes would be all but impossible to find."
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