PASADENA, CALIF. — Cosmic debris stripped away from
the wreck of colliding galaxies has been found by the Subaru telescope atop Mauna Kea, Hawaii.
The debris
fields could shed light on galaxy formation and starburst activity in the early
universe by allowing astronomers to retrace the paths of the colliding
galaxies before they merged.
"This
is equivalent to finally being able to trace the skid marks on the road when
investigating a car wreck," said team member Nick Scoville of the
California Institute of Technology.
Enormous
debris fields found
Astronomers
found the debris features in deep exposures of well-known colliding galaxies,
including "the Antennae" galaxies, 65 million light-years away in
the constellation Corvus, Arp 220 in the constellation Serpens (250 million
light-years away), Mrk 231 in the Big Dipper (590 million light-years away),
and 10 other objects. (A light year is the distance that light travels in a
year, about 6 trillion miles or 10 trillion kilometers.)
The extent
of the debris, some of which stretched over an area a few times larger than the
Milky Way, hadn't been seen in earlier images of these collisions, astronomers
said. A large extension of the Antennae was found to be twice the size
previously thought, and a new tidal tail was found trailing from Mrk 231.
"We
did not expect such enormous debris fields around these famous objects,"
said team member Jin Koda of Stony Brook University in New York.
The
discoveries were announced here today at the 214th meeting of the American
Astronomical Society.
Tidal
tails
Colliding
galaxies eventually merge and become a single galaxy. Our own Milky Way is fated
to collide and merge with the neighboring Andromeda galaxy in about 5
billion years.
The mutual
tug the galaxies exert on each other can pull pieces of each galaxy out in
different shapes.
One example
is so-called "tidal tails," which indicate a quick galactic merger.
When galaxies come together quickly, they could trigger starburst activity in
Ultra Luminous Infrared Galaxies (ULIRGs).
"Arp
220 is the most famous ULIRG," said team member Yoshiaki Taniguchi of Ehime University in Japan. "ULIRGs are very likely the dominant mode of cosmic star
formation in the early Universe, and Arp 220 is the key object to understand
starburst activities in ULIRGs."
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