Andrew Yee[_1_]
June 19th 08, 10:05 PM
Jennifer Morcone
Marshall Space Flight Center, Huntsville, Ala. June 18, 2008
256-544-7199
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
News release: 08-071
Black Holes Have Simple Feeding Habits
The biggest black holes may feed just like the smallest ones, according to
data from NASA's Chandra X-ray Observatory and ground-based telescopes. This
discovery supports the implication of Einstein's relativity theory that
black holes of all sizes have similar properties, and will be useful for
predicting the properties of a conjectured new class of black holes.
The conclusion comes from a large observing campaign of the spiral galaxy
M81, which is about 12 million light years from Earth. In the center of M81
is a black hole that is about 70 million times more massive than the Sun,
and generates energy and radiation as it pulls gas in the central region of
the galaxy inwards at high speed.
In contrast, so-called stellar mass black holes, which have about 10 times
more mass than the Sun, have a different source of food. These smaller black
holes acquire new material by pulling gas from an orbiting companion star.
Because the bigger and smaller black holes are found in different
environments with different sources of material to feed from, a question has
remained about whether they feed in the same way.
Using these new observations and a detailed theoretical model, a research
team compared the properties of M81's black hole with those of stellar mass
black holes. The results show that either big or little, black holes indeed
appear to eat similarly to each other, and produce a similar distribution of
X-rays, optical and radio light.
One of the implications of Einstein's theory of General Relativity is that
black holes are simple objects and only their masses and spins determine
their effect on space-time. The latest research indicates that this
simplicity manifests itself in spite of complicated environmental effects.
"This confirms that the feeding patterns for black holes of different sizes
can be very similar," said Sera Markoff of the Astronomical Institute,
University of Amsterdam in the Netherlands, who led the study. "We thought
this was the case, but up until now we haven't been able to nail it."
The model that Markoff and her colleagues used to study the black holes
includes a faint disk of material spinning around the black hole. This
structure would mainly produce X-rays and optical light. A region of hot gas
around the black hole would be seen largely in ultraviolet and X-ray light.
A large contribution to both the radio and X-ray light comes from jets
generated by the black hole. Multi-wavelength data is needed to disentangle
these overlapping sources of light.
"When we look at the data, it turns out that our model works just as well
for the giant black hole in M81 as it does for the smaller guys," said
Michael Nowak, a coauthor from the Massachusetts Institute of Technology.
"Everything around this huge black hole looks just the same except it's
almost 10 million times bigger."
Among actively feeding black holes the one in M81 is one of the dimmest,
presumably because it is "underfed". It is, however, one of the brightest as
seen from Earth because of its relative proximity, allowing high quality
observations to be made.
"It seems like the underfed black holes are the simplest in practice,
perhaps because we can see closer to the black hole," said Andrew Young of
the University of Bristol in England. "They don't seem to care too much
where they get their food from."
This work should be useful for predicting the properties of a third,
unconfirmed class called intermediate mass black holes, with masses lying
between those of stellar and supermassive black holes. Some possible members
of this class have been identified, but the evidence is controversial, so
specific predictions for the properties of these black holes should be very
helpful.
In addition to Chandra, three radio arrays (the Giant Meterwave Radio
Telescope, the Very Large Array and the Very Long Baseline Array), two
millimeter telescopes (the Plateau de Bure Interferometer and the
Submillimeter Array), and Lick Observatory in the optical were used to
monitor M81. These observations were made simultaneously to ensure that
brightness variations because of changes in feeding rates did not confuse
the results. Chandra is the only X-ray satellite able to isolate the faint
X-rays of the black hole from the emission of the rest of the galaxy.
This result confirms less detailed earlier work by Andrea Merloni from the
Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany
and colleagues that suggested that the basic properties of larger black
holes are similar to the smaller ones. Their study, however, was not based
on simultaneous, multi-wavelength observations nor the application of a
detailed physical model.
These results 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/2008/m81/
and
http://chandra.nasa.gov
Marshall Space Flight Center, Huntsville, Ala. June 18, 2008
256-544-7199
Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
News release: 08-071
Black Holes Have Simple Feeding Habits
The biggest black holes may feed just like the smallest ones, according to
data from NASA's Chandra X-ray Observatory and ground-based telescopes. This
discovery supports the implication of Einstein's relativity theory that
black holes of all sizes have similar properties, and will be useful for
predicting the properties of a conjectured new class of black holes.
The conclusion comes from a large observing campaign of the spiral galaxy
M81, which is about 12 million light years from Earth. In the center of M81
is a black hole that is about 70 million times more massive than the Sun,
and generates energy and radiation as it pulls gas in the central region of
the galaxy inwards at high speed.
In contrast, so-called stellar mass black holes, which have about 10 times
more mass than the Sun, have a different source of food. These smaller black
holes acquire new material by pulling gas from an orbiting companion star.
Because the bigger and smaller black holes are found in different
environments with different sources of material to feed from, a question has
remained about whether they feed in the same way.
Using these new observations and a detailed theoretical model, a research
team compared the properties of M81's black hole with those of stellar mass
black holes. The results show that either big or little, black holes indeed
appear to eat similarly to each other, and produce a similar distribution of
X-rays, optical and radio light.
One of the implications of Einstein's theory of General Relativity is that
black holes are simple objects and only their masses and spins determine
their effect on space-time. The latest research indicates that this
simplicity manifests itself in spite of complicated environmental effects.
"This confirms that the feeding patterns for black holes of different sizes
can be very similar," said Sera Markoff of the Astronomical Institute,
University of Amsterdam in the Netherlands, who led the study. "We thought
this was the case, but up until now we haven't been able to nail it."
The model that Markoff and her colleagues used to study the black holes
includes a faint disk of material spinning around the black hole. This
structure would mainly produce X-rays and optical light. A region of hot gas
around the black hole would be seen largely in ultraviolet and X-ray light.
A large contribution to both the radio and X-ray light comes from jets
generated by the black hole. Multi-wavelength data is needed to disentangle
these overlapping sources of light.
"When we look at the data, it turns out that our model works just as well
for the giant black hole in M81 as it does for the smaller guys," said
Michael Nowak, a coauthor from the Massachusetts Institute of Technology.
"Everything around this huge black hole looks just the same except it's
almost 10 million times bigger."
Among actively feeding black holes the one in M81 is one of the dimmest,
presumably because it is "underfed". It is, however, one of the brightest as
seen from Earth because of its relative proximity, allowing high quality
observations to be made.
"It seems like the underfed black holes are the simplest in practice,
perhaps because we can see closer to the black hole," said Andrew Young of
the University of Bristol in England. "They don't seem to care too much
where they get their food from."
This work should be useful for predicting the properties of a third,
unconfirmed class called intermediate mass black holes, with masses lying
between those of stellar and supermassive black holes. Some possible members
of this class have been identified, but the evidence is controversial, so
specific predictions for the properties of these black holes should be very
helpful.
In addition to Chandra, three radio arrays (the Giant Meterwave Radio
Telescope, the Very Large Array and the Very Long Baseline Array), two
millimeter telescopes (the Plateau de Bure Interferometer and the
Submillimeter Array), and Lick Observatory in the optical were used to
monitor M81. These observations were made simultaneously to ensure that
brightness variations because of changes in feeding rates did not confuse
the results. Chandra is the only X-ray satellite able to isolate the faint
X-rays of the black hole from the emission of the rest of the galaxy.
This result confirms less detailed earlier work by Andrea Merloni from the
Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany
and colleagues that suggested that the basic properties of larger black
holes are similar to the smaller ones. Their study, however, was not based
on simultaneous, multi-wavelength observations nor the application of a
detailed physical model.
These results 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/2008/m81/
and
http://chandra.nasa.gov