This
story was updated at 1:42 p.m. ET.
For the
first time astronomers have witnessed a supermassive black hole blasting its
galactic neighbor with a deadly beam of energy.
The
"death star galaxy," as NASA astronomers called it, could obliterate
the atmospheres of planets but also trigger the birth of stars in the wake of
its destructive beam. Fortunately, the
cosmic violence is a safe distance from our own neck of the cosmos.
"We've
seen many jets produced by black holes, but this is the first time we've seen
one punch into another galaxy like we're
seeing here," said Dan Evans, astronomer at the Harvard-Smithsonian
Center for Astrophysics in Cambridge, Mass. "This jet could be causing all
sorts of problems for the smaller galaxy it is pummeling."
Evans and
his colleagues detail their findings in an upcoming issue of the Astrophysical
Journal.
Cosmic
death
The deadly
galaxy — the largest of two in a system known as 3C321 — is aiming the
high-energy jet from its center at a smaller galaxy 20,000 light-years away
from it, or roughly the distance from Earth to the Milky Way's core. Both
galaxies are situated about 1.4 billion light-years away from Earth.
A bright
spot in a NASA composite image reveals that the beam is striking
the edge of the smaller galaxy, deflecting the spindle of energy into
intergalactic space. While not a direct hit, astronomers said the consequences
are frightening.
"This
is a fascinating result, and we can be glad that we're seeing it from a safe
distance," said Neil deGrasse Tyson, an astrophysicist at the American Museum of Natural History in New York who did not contribute to the study.
"Knowing how lethal the radiation from the jet could be, I wouldn't want
to be anywhere near its line of fire."
Jets from supermassive
black holes produce tremendous radiation in the form of X-rays, gamma rays
and electrons traveling close to the speed of light. Evans said, however, that
the X-ray and gamma-ray photons would ultimately do the most damage to planets.
"The
photons can have a really dramatic, profound effect on a planetary
atmosphere," he said. "It's likely the ozone layer on an Earth-like
planet would be destroyed within months."
Without an
ozone layer to protect a planet from deadly space radiation, Tyson said
creatures on a planet's surface would perish quickly.
"You
would basically render extinct all surface forms of life," Tyson said. "But
it may be that subterranean life is ... immune to this kind of violence in the
universe."
Recent
attack
The
offending galaxy probably began assaulting
its companion about 1 million years ago, which is relatively recent on a
cosmic time scale. Evans said the unusual event makes 3C321 an important object
for learning more about the universe.
"We've
seen jets do pretty weird things to their environments, but a head-on collision
is really rare and generates a [large] amount of information about physics that
we can understand and use," Evans said. "For that galaxy to be
looking right down ... the barrel of the gun of that jet is incredibly rare, so
this makes it a really exciting discovery."
Turns out
that the "death ray" may not be all bad news for the victimized
galaxy, at least theoretically, as such a massive influx of energy and
radiation could help form new stars and solar systems by compressing gases.
"In
the end [3C321] may be the source of new life in that distant galaxy,"
said Martin Hardcastle, an astronomer at the University of Hertfordshire, in the United Kingdom. Hardcastle explained that the jet will continue to pour
out of its parent supermassive black hole for about 10 to 100 million longer —
plenty of time to squeeze otherwise inert gas together into new star systems.
"Jets
can be highly disruptive ... but [create] stellar nurseries," Tyson said. "It's
a fascinating sort of duality about how these high-energy phenomena influence
the environments in which they're embedded."
To fully
view the galactic violence and rebirth, astronomers used NASA's Chandra X-ray
observatory, Hubble and Spitzer space telescopes, and the Very Large Array and
MERLIN radio telescopes on Earth.
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