Andrew Yee[_1_]
June 28th 07, 02:36 AM
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: June 27, 2007
Neutron Stars Join The Black Hole Jet Set
NASA's Chandra X-ray Observatory has revealed an X-ray jet blasting away
from a neutron star in a binary system. This discovery may help astronomers
understand how neutron stars as well as black holes can generate powerful
beams of relativistic particles.
The jet was found in Circinus X-1, a system where a neutron star is in orbit
around a star several times the mass of the Sun, about 20,000 light years
from Earth. A neutron star is an extremely dense remnant of an exploded star
consisting of tightly packed neutrons.
Many jets have been found originating near black holes -- both the
supermassive and stellar-mass variety -- but the Circinus X-1 jet is the
first extended X-ray jet associated with a neutron star in a binary system.
This detection shows that the unusual properties of black holes -- such as
presence of an event horizon and the lack of an actual surface -- may not be
required to form powerful jets.
The discovery of this jet with Chandra also reveals how efficient neutron
stars can be as cosmic power factories. Heinz and his colleagues estimate
that a surprisingly high percentage of the energy available from material
falling onto the neutron star is converted into powering the jet.
"In terms of energy efficiency across the Universe, this result shows that
neutron stars are near the top of the list," said Norbert Schulz, a coauthor
from the Massachusetts Institute of Technology in Cambridge. "This jet is
almost as efficient as one from a black hole."
The Chandra results also help to explain the origin of diffuse lobes of
radio emission previously detected around Circinus X-1. The team found the
X-ray jets of high-energy particles are powerful enough to create and
maintain these balloons of radio-emitting gas.
"We've seen enormous radio clouds around supermassive black holes at the
centers of galaxies," said Heinz. "What's unusual here is that this
pocket-sized version, relatively speaking, is being powered by a neutron
star, not a black hole."
The main evidence for the newly found jet comes in two extended features in
the Chandra data. These two fingers of X-ray emission are separated by about
30 degrees and may represent the outer walls of a wide jet. When overlapped
with radio images, these X-ray features, which are at least five light years
from the neutron star, closely trace the outline of the radio jet.
Another interpretation is that these two features represent two separate,
highly collimated jets produced at different times by a precessing neutron
star. That is, the neutron star wobbles like a top as it spins and the jet
fires at different angles at different times.
Jet precession is also consistent with radio observations taken at different
times, which show varying orientation angles of the jet. If the precession
scenario is correct, Circinus X-1 would possess one of the longest,
narrowest jets found in X-ray binary systems to date, representing yet
another way in which neutron stars can rival and even outdo their larger
black hole relatives.
These results will appear in an upcoming issue of The Astrophysical Journal
Letters. 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/cirx1/
and
http://www.nasa.gov/mission_pages/chandra/multimedia/photos07-077.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: June 27, 2007
Neutron Stars Join The Black Hole Jet Set
NASA's Chandra X-ray Observatory has revealed an X-ray jet blasting away
from a neutron star in a binary system. This discovery may help astronomers
understand how neutron stars as well as black holes can generate powerful
beams of relativistic particles.
The jet was found in Circinus X-1, a system where a neutron star is in orbit
around a star several times the mass of the Sun, about 20,000 light years
from Earth. A neutron star is an extremely dense remnant of an exploded star
consisting of tightly packed neutrons.
Many jets have been found originating near black holes -- both the
supermassive and stellar-mass variety -- but the Circinus X-1 jet is the
first extended X-ray jet associated with a neutron star in a binary system.
This detection shows that the unusual properties of black holes -- such as
presence of an event horizon and the lack of an actual surface -- may not be
required to form powerful jets.
The discovery of this jet with Chandra also reveals how efficient neutron
stars can be as cosmic power factories. Heinz and his colleagues estimate
that a surprisingly high percentage of the energy available from material
falling onto the neutron star is converted into powering the jet.
"In terms of energy efficiency across the Universe, this result shows that
neutron stars are near the top of the list," said Norbert Schulz, a coauthor
from the Massachusetts Institute of Technology in Cambridge. "This jet is
almost as efficient as one from a black hole."
The Chandra results also help to explain the origin of diffuse lobes of
radio emission previously detected around Circinus X-1. The team found the
X-ray jets of high-energy particles are powerful enough to create and
maintain these balloons of radio-emitting gas.
"We've seen enormous radio clouds around supermassive black holes at the
centers of galaxies," said Heinz. "What's unusual here is that this
pocket-sized version, relatively speaking, is being powered by a neutron
star, not a black hole."
The main evidence for the newly found jet comes in two extended features in
the Chandra data. These two fingers of X-ray emission are separated by about
30 degrees and may represent the outer walls of a wide jet. When overlapped
with radio images, these X-ray features, which are at least five light years
from the neutron star, closely trace the outline of the radio jet.
Another interpretation is that these two features represent two separate,
highly collimated jets produced at different times by a precessing neutron
star. That is, the neutron star wobbles like a top as it spins and the jet
fires at different angles at different times.
Jet precession is also consistent with radio observations taken at different
times, which show varying orientation angles of the jet. If the precession
scenario is correct, Circinus X-1 would possess one of the longest,
narrowest jets found in X-ray binary systems to date, representing yet
another way in which neutron stars can rival and even outdo their larger
black hole relatives.
These results will appear in an upcoming issue of The Astrophysical Journal
Letters. 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/cirx1/
and
http://www.nasa.gov/mission_pages/chandra/multimedia/photos07-077.html