Andrew Yee
January 13th 06, 05:10 AM
Public Affairs Office
Harvard-Smithsonian Center for Astrophysics
Cambridge, Massachusetts
For more information, contact:
David A. Aguilar, Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462
Christine Pulliam, Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
Phone: 617-495-7463, Fax: 617-495-7016
Release No.: 06-07
For Release: EMBARGOED until 9:20 a.m. EST, Thursday, January 12, 2006
New Maser Measurements Trace Detail in Active Galactic Core
Washington, DC -- The roiling cores of many active galaxies are difficult
to see in detail because of surrounding gas and interstellar dust.
Smithsonian astronomers announced today, however, a first-time measurement
that may help to better trace the structure of these unusual regions.
Elizabeth M. L. Humphreys and other Harvard-Smithsonian Center for
Astrophysics (CfA) research team members presented the first detection at
millimeter and submillimeter wavelengths of extragalactic water maser
emission in the core of active galaxy NGC 3079 in their paper at the 207th
meeting of the American Astronomical Society in Washington, D. C.
"Detections of water masers at these wavelengths will provide a unique new
means of determining the physical conditions near the center of active
galactic nuclei (AGN), where supermassive black holes are believed to
lie," said Humphreys.
The team measured radiation from compact radio sources known as H2O
(water) masers using the Smithsonian Astrophysical Observatory's
Submillimeter Array and the James Clerk Maxwell Telescope, both on Mauna
Kea, Hawaii. Masers amplify and beam radio-wave emission similar to the
way lasers emit light. Masers can occur in nature in interstellar space.
In our own galaxy, water molecules near hot, newly formed stars can absorb
energy and then emit radio waves with centimeter wavelengths, creating the
brightest spectral lines in the radio universe. In active galaxies, it is
processes related to black holes rather than stars that heat the
molecules.
Over millions of years, an immense hourglass-like bubble of hot gas has
emerged from the core of NGC 3079, a spiral galaxy 50 million light-years
away in the direction of the constellation Ursa Major. Astronomers have
vigorously debated whether the bubble is being shaped by radiation and
streams of particles released during a central burst of star formation or
processes directly related to the many-million solar-mass black hole at
the neck of the hourglass.
"If these masers are present in NGC 3079, they are doubtless present in
other active galaxies. Discovery of millimeter and submillimeter water
maser emission in an active galactic nucleus, in addition to the
long-known centimeter signal, opens new opportunities to map the location
of molecular gas in accretion disks and outflows perhaps just a few
light-years from a massive black hole," said Lincoln J. Greenhill of CfA.
Previously, Dr. Greenhill and student Paul Kondratko led a team that
mapped molecular material that lies in a roughly five-light-year diameter
disk around the black hole in NGC 3079, using just the centimeter
wavelength maser emission generated by this gas. Detailed comparison of
images from the Hubble Space Telescope, Chandra X-ray Observatory, and
Very Long Baseline Array of the National Radio Astronomy Observatory
demonstrated that the accretion disk and black hole lie at the neck of the
hourglass outflow.
"Although we do not yet have the angular resolution to tell if the
millimeter water emission originates from the disk or outflow or both, we
find that the peak in the emission is quite close to the centimeter
emission, and overlap in velocity is key," said Humphreys. It reinforces
the suggestion that individual maser components at different wavelengths
may exist in overlapping physical regions.
"If we can find H2O masers at different wavelengths in the same volumes of
gas as those emitting at centimeter wavelengths, then we can define
conditions there such as gas temperature and density much better," said
Mark J. Reid of CfA. "If we find them in different volumes as well, then
we can trace uncharted regions of the active galactic nucleus, including
those closer to the central black hole. This could shed new light on the
AGN accretion process that leads to formation of supermassive black
holes."
While centimeter emission is the signature for H2O, it has long been known
that H2O masers emit strongly at least 10 other wavelengths. These are
less well studied because relatively few telescopes can detect the
radiation, much of which is blocked by the atmosphere.
"We made the observation using the first imaging interferometer working at
submillimeter wavelengths ever, the Submillimeter Array of the Smithsonian
Astrophysical Observatory," said James M. Moran of CfA. (The SMA is an
8-element radio interferometer located atop Mauna Kea in Hawaii that also
operates at millimeter wavelengths.) "The SMA's imaging capability showed
that the millimeter water emission is associated with the central region
of NGC 3079, as is the warm dust emission that we also detected."
The Submillimeter Array is a joint venture of the Smithsonian
Astrophysical Observatory and the Academia Sinica Institute of Astronomy
and Astrophysics.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics (CfA) is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists, organized into six research divisions, study the origin,
evolution and ultimate fate of the universe.
Note to editors: Images to accompany this release are online at
http://www.cfa.harvard.edu/press/pr0607image.html
Harvard-Smithsonian Center for Astrophysics
Cambridge, Massachusetts
For more information, contact:
David A. Aguilar, Director of Public Affairs
Harvard-Smithsonian Center for Astrophysics
617-495-7462
Christine Pulliam, Public Affairs Specialist
Harvard-Smithsonian Center for Astrophysics
Phone: 617-495-7463, Fax: 617-495-7016
Release No.: 06-07
For Release: EMBARGOED until 9:20 a.m. EST, Thursday, January 12, 2006
New Maser Measurements Trace Detail in Active Galactic Core
Washington, DC -- The roiling cores of many active galaxies are difficult
to see in detail because of surrounding gas and interstellar dust.
Smithsonian astronomers announced today, however, a first-time measurement
that may help to better trace the structure of these unusual regions.
Elizabeth M. L. Humphreys and other Harvard-Smithsonian Center for
Astrophysics (CfA) research team members presented the first detection at
millimeter and submillimeter wavelengths of extragalactic water maser
emission in the core of active galaxy NGC 3079 in their paper at the 207th
meeting of the American Astronomical Society in Washington, D. C.
"Detections of water masers at these wavelengths will provide a unique new
means of determining the physical conditions near the center of active
galactic nuclei (AGN), where supermassive black holes are believed to
lie," said Humphreys.
The team measured radiation from compact radio sources known as H2O
(water) masers using the Smithsonian Astrophysical Observatory's
Submillimeter Array and the James Clerk Maxwell Telescope, both on Mauna
Kea, Hawaii. Masers amplify and beam radio-wave emission similar to the
way lasers emit light. Masers can occur in nature in interstellar space.
In our own galaxy, water molecules near hot, newly formed stars can absorb
energy and then emit radio waves with centimeter wavelengths, creating the
brightest spectral lines in the radio universe. In active galaxies, it is
processes related to black holes rather than stars that heat the
molecules.
Over millions of years, an immense hourglass-like bubble of hot gas has
emerged from the core of NGC 3079, a spiral galaxy 50 million light-years
away in the direction of the constellation Ursa Major. Astronomers have
vigorously debated whether the bubble is being shaped by radiation and
streams of particles released during a central burst of star formation or
processes directly related to the many-million solar-mass black hole at
the neck of the hourglass.
"If these masers are present in NGC 3079, they are doubtless present in
other active galaxies. Discovery of millimeter and submillimeter water
maser emission in an active galactic nucleus, in addition to the
long-known centimeter signal, opens new opportunities to map the location
of molecular gas in accretion disks and outflows perhaps just a few
light-years from a massive black hole," said Lincoln J. Greenhill of CfA.
Previously, Dr. Greenhill and student Paul Kondratko led a team that
mapped molecular material that lies in a roughly five-light-year diameter
disk around the black hole in NGC 3079, using just the centimeter
wavelength maser emission generated by this gas. Detailed comparison of
images from the Hubble Space Telescope, Chandra X-ray Observatory, and
Very Long Baseline Array of the National Radio Astronomy Observatory
demonstrated that the accretion disk and black hole lie at the neck of the
hourglass outflow.
"Although we do not yet have the angular resolution to tell if the
millimeter water emission originates from the disk or outflow or both, we
find that the peak in the emission is quite close to the centimeter
emission, and overlap in velocity is key," said Humphreys. It reinforces
the suggestion that individual maser components at different wavelengths
may exist in overlapping physical regions.
"If we can find H2O masers at different wavelengths in the same volumes of
gas as those emitting at centimeter wavelengths, then we can define
conditions there such as gas temperature and density much better," said
Mark J. Reid of CfA. "If we find them in different volumes as well, then
we can trace uncharted regions of the active galactic nucleus, including
those closer to the central black hole. This could shed new light on the
AGN accretion process that leads to formation of supermassive black
holes."
While centimeter emission is the signature for H2O, it has long been known
that H2O masers emit strongly at least 10 other wavelengths. These are
less well studied because relatively few telescopes can detect the
radiation, much of which is blocked by the atmosphere.
"We made the observation using the first imaging interferometer working at
submillimeter wavelengths ever, the Submillimeter Array of the Smithsonian
Astrophysical Observatory," said James M. Moran of CfA. (The SMA is an
8-element radio interferometer located atop Mauna Kea in Hawaii that also
operates at millimeter wavelengths.) "The SMA's imaging capability showed
that the millimeter water emission is associated with the central region
of NGC 3079, as is the warm dust emission that we also detected."
The Submillimeter Array is a joint venture of the Smithsonian
Astrophysical Observatory and the Academia Sinica Institute of Astronomy
and Astrophysics.
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics (CfA) is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists, organized into six research divisions, study the origin,
evolution and ultimate fate of the universe.
Note to editors: Images to accompany this release are online at
http://www.cfa.harvard.edu/press/pr0607image.html