Andrew Yee[_1_]
June 6th 07, 07:25 PM
Steve Roy
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-6535)
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
(Phone: 617/496-7998)
For Release: May 30, 2007
Galaxy Cluster Takes It to the Extreme
Evidence for an awesome upheaval in a massive galaxy cluster was discovered
in an image made by NASA's Chandra X-ray Observatory. The origin of a bright
arc of ferociously hot gas extending over two million light years requires
one of the most energetic events ever detected.
The cluster of galaxies is filled with tenuous gas at 170 million degree
Celsius that is bound by the mass equivalent of a quadrillion, or 1,000
trillion, suns. The temperature and mass make this cluster a giant among
giants.
"The huge feature detected in the cluster, combined with the high
temperature, points to an exceptionally dramatic event in the nearby
Universe," said Ralph Kraft of the Harvard-Smithsonian Center for
Astrophysics (CfA) in Cambridge, Mass., and leader of a team of astronomers
involved in this research. "While we're not sure what caused it, we've
narrowed it down to a couple of exciting possibilities."
The favored explanation for the bright X-ray arc is that two massive galaxy
clusters are undergoing a collision at about 4 million miles per hour. Shock
waves generated by the violent encounter of the clusters' hot gas clouds
could produce a sharp change in pressure along the boundary where the
collision is occurring, giving rise to the observed arc-shaped structure
which resembles a titanic weather front.
"Although this would be an extreme collision, one of the most powerful ever
seen, we think this may be what is going on," said team member Martin
Hardcastle, of the University of Hertfordshire, United Kingdom.
A problem with the collision theory is that only one peak in the X-ray
emission is seen, whereas two are expected. Longer observations with Chandra
and the XMM-Newton X-ray observatories should help determine how serious
this problem is for the collision hypothesis.
Another possible explanation is that the disturbance was caused by an
outburst generated by the infall of matter into a supermassive black hole
located in a central galaxy. The black hole inhales much of the matter but
expels some of it outward in a pair of high-speed jets, heating and pushing
aside the surrounding gas.
Such events are known to occur in this cluster. The galaxy 3C438 in the
central region of the cluster is known to be a powerful source of explosive
activity, which is presumably due to a central supermassive black hole. But
the energy in these outbursts is not nearly large enough to explain the
Chandra data.
"If this event was an outburst from a supermassive black hole, then it's by
far the most powerful one ever seen," said team member Bill Forman, also of
CfA.
The phenomenal amount of energy involved implies a very large amount of mass
would have been swallowed by the black hole, about 30 billion times the
Sun's mass over a period of 200 million years. The authors consider this
rate of black hole growth implausible.
"These values have never been seen before and, truthfully, are hard to
believe," said Kraft.
These results were presented at the American Astronomical Society meeting in
Honolulu, HI, and will appear in an upcoming issue of The Astrophysical
Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the
Chandra program for the agency's Science Mission Directorate. The
Smithsonian Astrophysical Observatory controls science and flight operations
from the Chandra X-ray Center in Cambridge, Mass.
Additional information and images are available at:
http://chandra.harvard.edu/photo/2007/3c438/
and
http://www.nasa.gov/mission_pages/chandra/multimedia/photos07-052.html
Marshall Space Flight Center, Huntsville, Ala.
(Phone: 256/544-6535)
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
(Phone: 617/496-7998)
For Release: May 30, 2007
Galaxy Cluster Takes It to the Extreme
Evidence for an awesome upheaval in a massive galaxy cluster was discovered
in an image made by NASA's Chandra X-ray Observatory. The origin of a bright
arc of ferociously hot gas extending over two million light years requires
one of the most energetic events ever detected.
The cluster of galaxies is filled with tenuous gas at 170 million degree
Celsius that is bound by the mass equivalent of a quadrillion, or 1,000
trillion, suns. The temperature and mass make this cluster a giant among
giants.
"The huge feature detected in the cluster, combined with the high
temperature, points to an exceptionally dramatic event in the nearby
Universe," said Ralph Kraft of the Harvard-Smithsonian Center for
Astrophysics (CfA) in Cambridge, Mass., and leader of a team of astronomers
involved in this research. "While we're not sure what caused it, we've
narrowed it down to a couple of exciting possibilities."
The favored explanation for the bright X-ray arc is that two massive galaxy
clusters are undergoing a collision at about 4 million miles per hour. Shock
waves generated by the violent encounter of the clusters' hot gas clouds
could produce a sharp change in pressure along the boundary where the
collision is occurring, giving rise to the observed arc-shaped structure
which resembles a titanic weather front.
"Although this would be an extreme collision, one of the most powerful ever
seen, we think this may be what is going on," said team member Martin
Hardcastle, of the University of Hertfordshire, United Kingdom.
A problem with the collision theory is that only one peak in the X-ray
emission is seen, whereas two are expected. Longer observations with Chandra
and the XMM-Newton X-ray observatories should help determine how serious
this problem is for the collision hypothesis.
Another possible explanation is that the disturbance was caused by an
outburst generated by the infall of matter into a supermassive black hole
located in a central galaxy. The black hole inhales much of the matter but
expels some of it outward in a pair of high-speed jets, heating and pushing
aside the surrounding gas.
Such events are known to occur in this cluster. The galaxy 3C438 in the
central region of the cluster is known to be a powerful source of explosive
activity, which is presumably due to a central supermassive black hole. But
the energy in these outbursts is not nearly large enough to explain the
Chandra data.
"If this event was an outburst from a supermassive black hole, then it's by
far the most powerful one ever seen," said team member Bill Forman, also of
CfA.
The phenomenal amount of energy involved implies a very large amount of mass
would have been swallowed by the black hole, about 30 billion times the
Sun's mass over a period of 200 million years. The authors consider this
rate of black hole growth implausible.
"These values have never been seen before and, truthfully, are hard to
believe," said Kraft.
These results were presented at the American Astronomical Society meeting in
Honolulu, HI, and will appear in an upcoming issue of The Astrophysical
Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the
Chandra program for the agency's Science Mission Directorate. The
Smithsonian Astrophysical Observatory controls science and flight operations
from the Chandra X-ray Center in Cambridge, Mass.
Additional information and images are available at:
http://chandra.harvard.edu/photo/2007/3c438/
and
http://www.nasa.gov/mission_pages/chandra/multimedia/photos07-052.html