Jet From Supermassive Black Hole Seen Blasting Neighboring Galaxy

By Marc Kaufman
Washington Post Staff Writer
Tuesday, December 18, 2007; A03



A jet of highly charged radiation from a supermassive black hole at
the center of a distant galaxy is blasting another galaxy nearby -- an
act of galactic violence that astronomers said yesterday they have
never seen before.

Using images from the orbiting Chandra X-Ray Observatory and other
sources, scientists said the extremely intense jet from the larger
galaxy can be seen shooting across 20,000 light-years of space and
plowing into the outer gas and dust of the smaller one.

The smaller galaxy is being transformed by the radiation and the jet
is being bent before shooting millions of light-years farther in a new
direction.

"What we've identified is an act of violence by a black hole, with an
unfortunate nearby galaxy in the line of fire," said Dan Evans, the
study leader at the Harvard-Smithsonian Center for Astrophysics in
Cambridge. He said any planets orbiting the stars of the smaller
galaxy would be dramatically affected, and any life forms would likely
die as the jet's radiation transformed the planets' atmosphere.

Black holes are generally thought of as mysterious cosmic phenomena
that swallow matter, but the supermassive ones that occur at the
center of many -- possibly all -- galaxies also set loose tremendous
bursts of energy as matter swirls around the disk of material that
circles the black hole but does not make it in.

That energy, often in the form of highly charged gamma rays and X-
rays, shoots out in powerful jets that can be millions of light-years
long and 1,000 light-years wide.

Scientists are just beginning to understand these jets, which not only
transform matter in their path but also help produce "stellar
nurseries," where new stars are formed.

Evans's collaborator, Martin Hardcastle of the University of
Hertfordshire in England, said the collision they have identified
began no more than 1 million years ago and could continue for 10
million to 100 million more years. Hardcastle called the collision a
great opportunity to learn more about the jets.

"We see jets all over the universe, but we're still struggling to
understand some of their basic properties," he said. "This
system . . . gives us a chance to learn how they're affected when they
slam into something -- like a galaxy -- and what they do after that."

The two galaxies are more than 1.4 billion light-years away from the
Milky Way galaxy (a light-year equals about 6 trillion miles). But
they are close to each other in cosmic terms -- about as far as the
distance from Earth to the center of the Milky Way. That the two
appear to be moving toward a merger may have played a role in creating
such a powerful jet from the larger galaxy's central black hole.

The researchers said that the collision would have no effect on Earth,
but the process is one that could play out in our galaxy a billion
years into the future.

The galaxy Andromeda is the closest to the Milky Way, and the two are
gradually coming closer to each other. In time, astronomers say, the
two will merge, and the process may cause the dormant central black
holes in either the Milky Way or Andromeda to become active and begin
sending out similarly powerful jets.

If a jet were to hit Earth, Evans said, it would destroy the ozone
layer and collapse the magnetosphere that blankets the planet and
protects it from harmful solar particles. Without the ozone layer and
magnetosphere, he said, much of life on Earth would end.

"This jet could be causing all sorts of problems for the smaller
galaxy it is pummeling," Evans said.

Neil deGrasse Tyson, an astrophysicist from the American Museum of
Natural History in New York, said the discovery illustrates how
researchers can now observe astronomical phenomena using many
different tools and understand how they behave at many different
points along the electromagnetic spectrum. Only when scientists
measure a galaxy at all different wavelengths, he said, "can you
really understand what's going on."

In making their discovery, the researchers used data from three
orbiting instruments -- the Chandra X-ray Observatory, the Hubble
Space Telescope and Spitzer Space Telescope -- as well as ground-based
observatories including the Very Large Array telescope in New Mexico
and Britain's Multi-Element Radio Linked Interferometer Network. The
Astrophysical Journal will publish the results next year.

(c) 2007 The Washington Post Company