Where is that cotton pickin curve?
(i.e.: Radius of Curvature of all Natural Law)
Illusions Delusions and Real
......................................................................................................................
Circumference speed of black hole ....................Light Speed
20,000 miles per sec ....................................... 186,282.40 miles per sec
1,200,000 miles per min ................................ 11,176,944 miles per min
72,000,000 miles per hr ................................. 670,616,629 miles per hr
20,000 miles per sec ....................................... 186,282.40 miles per sec
1,200,000 miles per min ................................ 11,176,944 miles per min
72,000,000 miles per hr ................................. 670,616,629 miles per hr
The approximate value of 3×108 m/s is commonly used in rough estimates. In imperial units, the speed of light is about 670,616,629.2 miles per hour or 983,571,056 feet per second, which is about 186,282.397 miles per second, or roughly one foot per nanosecond.
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..............................................................
A Race Round a Black Hole
So you think rockets are fast? Scientists have spotted something going much faster. Like state troopers on a highway, these scientists used a "speed gun" to clock clumps of hot iron gas whipping around a black hole at 20,000 miles per second. That's over 10 percent of light speed.At this speed, you could get to the moon in about 10 seconds. The black hole's extreme pull of gravity is causing the gas to move so quickly. Image to left: This animation depicts three hot blobs of matter orbiting a black hole. If placed in our Solar System, this black hole would appear like a dark abyss spread out nearly as wide as Mercury's orbit. And the three blobs (each as large as the Sun) would be as far out as Jupiter. They orbit the black hole in a lightning-quick 20,000 miles per second, over a tenth of the speed of light. Click on image to view animation. Click here for a high resolution still from the animation (9.8 MB) Credit: NASA/Dana Berry, SkyWorks DigitalDr. Jane Turner of NASA Goddard Space Flight Center led the observation. She used a satellite launched by the European Space Agency called XMM-Newton. She said that this kind of measurement has never been done before."For years we have seen only the general commotion caused by massive black holes, that is, a terrific outpouring of light," Dr. Turner said. "We could not track the specifics. Now we can filter through all that light and find patterns that reveal information about black holes never seen before in such clarity."This is big news for black hole hunters because the observation marks the first time scientists could trace individual blobs of shredded matter on a complete journey around a black hole. This provides a crucial measurement that has long been missing from black hole studies: an orbital period. Knowing this, scientists can measure black hole mass and other characteristics that have long eluded them.Black holes are regions in space so dense that gravity prevents all matter and light from escaping. What scientists see is not the black hole itself but rather the light emitted close to it as matter falls towards the black hole and heats to high temperatures.Image to right: This is a simplified illustration of two hot blobs orbiting a black hole, showing how scientists tracked the blobs by observing their Doppler shift. First, we see one blob. Note how the energy emitted from this orbiting material rises to about 6.5 kilo-electron volts (an energy unit) as it moves towards us, and then falls to about 5.8 kilo-electron volts as it moves away. This is the Doppler effect, the same phenomenon that law officers exploit to nab speeders on a highway. Matter goes round and round; energy goes up and down. About 14 seconds into the animation, the artist adds a second blob which also displays a rise and fall in energy during its orbit. Click on image to view animation. Click here for high resolution still from animation (3.0 MB). Credit: NASA/Dana Berry, SkyWorks DigitalIf this black hole were placed in our Solar System, it would appear like a dark abyss spread out nearly as wide as Mercury's orbit. And the clumps of matter detected would be as far out as Jupiter. The clumps orbit the black hole in a lightning-quick 27 hours (compared to the 12 years it takes Jupiter to orbit the Sun).But this black hole is far, far away. Dr. Turner's team observed it in a well-known galaxy named Markarian 766, about 170 million light years away in the constellation Coma Berenices (Bernice's Hair). The black hole in Markarian 766 is relatively small although highly active. Its mass is a few million times that of the Sun. Other central black hole systems are over 100 million solar masses.Matter funnels into this black hole like water swirling down a drain, forming what scientists call an accretion disk. Flares erupt on this disk most likely when magnetic field lines emanating from the central black hole interact with regions on the disk. Zap! These flares are very hot. They glow in X-ray light, which is thousands of times more energetic that the visible light our eyes can detect. XMM-Newton is a special kind of telescope that can detect X-ray light, but not visible light. The Hubble Space Telescope, on the other hand, detects visible and ultraviolet light, but not X rays."Calculating the speeds of the flares and the black hole mass was straightforward, based on Doppler shifting, the technique used by law officers to nab speeders." said Dr. Ian George of NASA Goddard. (Both Drs. Turner and George hold teaching positions at the University of Maryland, Baltimore County.) "Light appears to rise in energy as an object moves towards us and then fall in energy as it moves away. A similar phenomenon happens with the sound of a passing car on a highway, going 'eeeeeeyyoool.'"When the scientists made a graph of energy (on the y-axis) and time (on the x-axis), they saw near-perfect sinusoidal curves from each of the three clumps of matter they observed. Up and down, up and down. The width (or period) of the curves is proportional to black hole mass. The height (or amplitude) of the curves is related to the viewing angle of the accretion disk. With a known mass and orbital period, the scientists could determine velocity using the relatively simple and traditional physics of Isaac Newton. Scientists do these kinds of measurements in the Solar System all the time. For example, if the Sun were bigger or if the Earth were closer to the Sun, our orbit would be faster because the tug of gravity would be stronger. That is, mass, distance and gravity dictate the speed and shape of orbits. Knowing one set of information helps you determine the other.Two factors made the black hole measurement possible. The scientists observed particularly persistent flares during a long observation, nearly 27 hours. Also, no telescope before XMM-Newton has had the light-collecting power to allow for a comparison of energy over time.Dr. Turner said this observation confirms a preliminary XMM-Newton result announced by a European team in September -- that something as detailed as an orbital period could be detected with the current generation of X-ray telescopes. The combination of results indicates that scientists, given long observation times, are now able to make careful black hole measurements and even test general relativity in the domain of extreme gravity.And moving 20,000 miles per second, these blobs around the black hole are taking scientists on an exciting ride.For additional graphs and information about the story presented above, click here.For the press release that was issued by NASA on this, click here.
Dr. Jane TurnerImage to left: Dr. Jane TurnerJane Turner is an expert on active galactic nuclei, which concerns those galaxies such as quasars thought to contain an actively accreting supermassive black hole at their cores. She currently holds joint affiliations as a Research Associate Professor in the physics department at the University of Maryland, Baltimore County (UMBC), and as a research scientist at NASA Goddard Space Flight Center. At UMBC she teaches Extragalactic Astronomy and Cosmology and introductory astronomy. She first came to NASA Goddard in 1988 to study X-ray emission from active galaxies. Her work has entailed analysis of data from a large variety of X-ray instruments on U.S. satellites and from U.S. collaborative missions worldwide. Highlights include supporting the Broad Band X-ray Telescope (BBXRT) mission as timeline planner, when it flew on shuttle mission STS-35, and being awarded a five-year NASA research grant in 1997. With Dr. Kirpal Nandra she has constructed a large archive database of reduced spectra, images and light curves of ASCA observations of active galaxies, known as the TARTARUS project, freely available on the Internet at http://tartarus.gsfc.nasa.gov. Dr. Turner received her B.S. in Mathematics with Astronomy in 1984 and her Ph.D. in Astronomy in 1988, both from the University of Leicester in the United Kingdom.Dr. Lance MillerImage to left: Dr. Lance MillerLance Miller teaches physics and astrophysics at Oxford University. His research focuses on studying the largest-scale structures in the universe through the distribution of active galaxies and quasars, as well as the phenomenon of supermassive black hole accretion. Dr. Miller obtained his Ph.D. in astrophysics from Cambridge University in 1983 and also worked at the Royal Observatory Edinburgh and the University of Edinburgh before moving to Oxford in 1996.Christopher WanjekGoddard Space Flight Center
Find this article at:http://www.nasa.gov/centers/goddard/universe/blackhole_race.html
Astronomers Measure Mass Of Smallest Black Hole In A Galactic Nucleus
NGC 4395. (Photo credit: Allan Sandage, Carnegie Institution)
ScienceDaily (Mar. 2, 2005) — Washington, DC - A group led by astronomers from Ohio State University and the Technion-Israel Institute of Technology have measured the mass of a unique black hole, and determined that it is the smallest found so far.
Early results indicate that the black hole weighs in at less than a million times the mass of our sun -– which would make it as much as 100 times smaller than others of its type.
To get their measurement, astronomers used NASA’s Hubble Space Telescope and a technique similar to Doppler radar -- the method that meteorologists use to track weather systems.
The black hole lies 14 million light-years away, in the center of the galaxy NGC 4395. One light-year is the distance light travels in one year -- approximately six trillion miles.
Astronomers consider NGC 4395 to be an “active galaxy,” one with a very bright center, or nucleus. Current theory holds that black holes may literally be consuming active galactic nuclei (AGNs). Black holes in AGNs are supposed to be very massive.
NGC 4395 appears to be special, because the black hole in the center of the galaxy is much smaller than those found in other active galaxies, explained Ari Laor, professor of astronomy at the Technion, in Haifa, Israel, and Brad Peterson, professor of astronomy at Ohio State.
While astronomers have found much evidence of black holes that are larger than a million solar masses or smaller than a few tens of solar masses, they haven’t found as many midsize black holes -- ones on the scale of hundreds or thousands of solar masses.
Black holes such as the one in NGC 4395 provide a step in closing that gap.
Laor and Peterson and their colleagues used the Doppler radar-like technique to track the movement of gas around the center of NGC 4395. Whereas radar bounces a radio frequency signal off of an object, the astronomers observed light signals that naturally emanated from the center of the galaxy, and timed how long those signals took to reach the orbiting gas.
The method is called reverberation mapping, and Peterson’s team is among a small number of groups who are developing it as a reliable means of measuring black hole masses. The method works because gas orbits faster around massive black holes than it does around smaller ones.
Peterson reported the early results Saturday at the meeting of the American Association for the Advancement of Science in Washington, DC.
Two of the team members -- Luis Ho of the Observatories of the Carnegie Institution of Washington, and Alex Fillippenko of the University of California, Berkeley -- were the first to suspect that the black hole mass was very small. Filippenko and Wallace L.W. Sargent of the California Institute of Technology first discovered the black hole in 1989.
This is the first time astronomers have been able to measure the mass of the black hole in NGC 4395, and confirm that it is indeed smaller than others of its kind.
Peterson and Laor emphasized that the results are very preliminary, but the black hole seems to be at least a hundred times smaller than any other black hole ever detected inside an AGN.
The astronomers want to refine that estimate before they address the next most logical question: why is the black hole so small?
“Is it the runt of the litter, or did it just happen to form under special circumstances? We don’t know yet,” Peterson said.
NGC 4395 doesn’t appear to have a dense spherical nucleus, called a galactic bulge, at its center; it could be that the black hole “ate” all the stars in the bulge, and doesn’t have any more food within reach. That would keep the black hole from growing.
Team members are most interested in what the black hole measurement can tell astronomers about AGNs in general. Any new information could help astronomers better understand the role that black holes play in making galaxies like our own form and evolve. To that end, the team is also studying related data from NASA’s Chandra X-ray Observatory and ground-based telescopes.
“It’s these extreme types of objects that really allow you to test your theories,” Peterson said.
Adapted from materials provided by Ohio State University.
===========================================================
Black Hole Food
So you think rockets are fast? Scientists have spotted something going much faster. Like state troopers on a highway, these scientists used a "speed gun" to clock clumps of hot iron gas whipping around a black hole at 20,000 miles per second. That's over 10 percent of light speed.At this speed, you could get to the moon in about 10 seconds. The black hole's extreme pull of gravity is causing the gas to move so quickly. Image to left: This animation depicts three hot blobs of matter orbiting a black hole. If placed in our Solar System, this black hole would appear like a dark abyss spread out nearly as wide as Mercury's orbit. And the three blobs (each as large as the Sun) would be as far out as Jupiter. They orbit the black hole in a lightning-quick 20,000 miles per second, over a tenth of the speed of light. Click on image to view animation. Click here for a high resolution still from the animation (9.8 MB) Credit: NASA/Dana Berry, SkyWorks DigitalDr. Jane Turner of NASA Goddard Space Flight Center led the observation. She used a satellite launched by the European Space Agency called XMM-Newton. She said that this kind of measurement has never been done before."For years we have seen only the general commotion caused by massive black holes, that is, a terrific outpouring of light," Dr. Turner said. "We could not track the specifics. Now we can filter through all that light and find patterns that reveal information about black holes never seen before in such clarity."This is big news for black hole hunters because the observation marks the first time scientists could trace individual blobs of shredded matter on a complete journey around a black hole. This provides a crucial measurement that has long been missing from black hole studies: an orbital period. Knowing this, scientists can measure black hole mass and other characteristics that have long eluded them.Black holes are regions in space so dense that gravity prevents all matter and light from escaping. What scientists see is not the black hole itself but rather the light emitted close to it as matter falls towards the black hole and heats to high temperatures.Image to right: This is a simplified illustration of two hot blobs orbiting a black hole, showing how scientists tracked the blobs by observing their Doppler shift. First, we see one blob. Note how the energy emitted from this orbiting material rises to about 6.5 kilo-electron volts (an energy unit) as it moves towards us, and then falls to about 5.8 kilo-electron volts as it moves away. This is the Doppler effect, the same phenomenon that law officers exploit to nab speeders on a highway. Matter goes round and round; energy goes up and down. About 14 seconds into the animation, the artist adds a second blob which also displays a rise and fall in energy during its orbit. Click on image to view animation. Click here for high resolution still from animation (3.0 MB). Credit: NASA/Dana Berry, SkyWorks DigitalIf this black hole were placed in our Solar System, it would appear like a dark abyss spread out nearly as wide as Mercury's orbit. And the clumps of matter detected would be as far out as Jupiter. The clumps orbit the black hole in a lightning-quick 27 hours (compared to the 12 years it takes Jupiter to orbit the Sun).But this black hole is far, far away. Dr. Turner's team observed it in a well-known galaxy named Markarian 766, about 170 million light years away in the constellation Coma Berenices (Bernice's Hair). The black hole in Markarian 766 is relatively small although highly active. Its mass is a few million times that of the Sun. Other central black hole systems are over 100 million solar masses.Matter funnels into this black hole like water swirling down a drain, forming what scientists call an accretion disk. Flares erupt on this disk most likely when magnetic field lines emanating from the central black hole interact with regions on the disk. Zap! These flares are very hot. They glow in X-ray light, which is thousands of times more energetic that the visible light our eyes can detect. XMM-Newton is a special kind of telescope that can detect X-ray light, but not visible light. The Hubble Space Telescope, on the other hand, detects visible and ultraviolet light, but not X rays."Calculating the speeds of the flares and the black hole mass was straightforward, based on Doppler shifting, the technique used by law officers to nab speeders." said Dr. Ian George of NASA Goddard. (Both Drs. Turner and George hold teaching positions at the University of Maryland, Baltimore County.) "Light appears to rise in energy as an object moves towards us and then fall in energy as it moves away. A similar phenomenon happens with the sound of a passing car on a highway, going 'eeeeeeyyoool.'"When the scientists made a graph of energy (on the y-axis) and time (on the x-axis), they saw near-perfect sinusoidal curves from each of the three clumps of matter they observed. Up and down, up and down. The width (or period) of the curves is proportional to black hole mass. The height (or amplitude) of the curves is related to the viewing angle of the accretion disk. With a known mass and orbital period, the scientists could determine velocity using the relatively simple and traditional physics of Isaac Newton. Scientists do these kinds of measurements in the Solar System all the time. For example, if the Sun were bigger or if the Earth were closer to the Sun, our orbit would be faster because the tug of gravity would be stronger. That is, mass, distance and gravity dictate the speed and shape of orbits. Knowing one set of information helps you determine the other.Two factors made the black hole measurement possible. The scientists observed particularly persistent flares during a long observation, nearly 27 hours. Also, no telescope before XMM-Newton has had the light-collecting power to allow for a comparison of energy over time.Dr. Turner said this observation confirms a preliminary XMM-Newton result announced by a European team in September -- that something as detailed as an orbital period could be detected with the current generation of X-ray telescopes. The combination of results indicates that scientists, given long observation times, are now able to make careful black hole measurements and even test general relativity in the domain of extreme gravity.And moving 20,000 miles per second, these blobs around the black hole are taking scientists on an exciting ride.For additional graphs and information about the story presented above, click here.For the press release that was issued by NASA on this, click here.
Dr. Jane TurnerImage to left: Dr. Jane TurnerJane Turner is an expert on active galactic nuclei, which concerns those galaxies such as quasars thought to contain an actively accreting supermassive black hole at their cores. She currently holds joint affiliations as a Research Associate Professor in the physics department at the University of Maryland, Baltimore County (UMBC), and as a research scientist at NASA Goddard Space Flight Center. At UMBC she teaches Extragalactic Astronomy and Cosmology and introductory astronomy. She first came to NASA Goddard in 1988 to study X-ray emission from active galaxies. Her work has entailed analysis of data from a large variety of X-ray instruments on U.S. satellites and from U.S. collaborative missions worldwide. Highlights include supporting the Broad Band X-ray Telescope (BBXRT) mission as timeline planner, when it flew on shuttle mission STS-35, and being awarded a five-year NASA research grant in 1997. With Dr. Kirpal Nandra she has constructed a large archive database of reduced spectra, images and light curves of ASCA observations of active galaxies, known as the TARTARUS project, freely available on the Internet at http://tartarus.gsfc.nasa.gov. Dr. Turner received her B.S. in Mathematics with Astronomy in 1984 and her Ph.D. in Astronomy in 1988, both from the University of Leicester in the United Kingdom.Dr. Lance MillerImage to left: Dr. Lance MillerLance Miller teaches physics and astrophysics at Oxford University. His research focuses on studying the largest-scale structures in the universe through the distribution of active galaxies and quasars, as well as the phenomenon of supermassive black hole accretion. Dr. Miller obtained his Ph.D. in astrophysics from Cambridge University in 1983 and also worked at the Royal Observatory Edinburgh and the University of Edinburgh before moving to Oxford in 1996.Christopher WanjekGoddard Space Flight Center
Find this article at:http://www.nasa.gov/centers/goddard/universe/blackhole_race.html
Astronomers Measure Mass Of Smallest Black Hole In A Galactic Nucleus
NGC 4395. (Photo credit: Allan Sandage, Carnegie Institution)
ScienceDaily (Mar. 2, 2005) — Washington, DC - A group led by astronomers from Ohio State University and the Technion-Israel Institute of Technology have measured the mass of a unique black hole, and determined that it is the smallest found so far.
Early results indicate that the black hole weighs in at less than a million times the mass of our sun -– which would make it as much as 100 times smaller than others of its type.
To get their measurement, astronomers used NASA’s Hubble Space Telescope and a technique similar to Doppler radar -- the method that meteorologists use to track weather systems.
The black hole lies 14 million light-years away, in the center of the galaxy NGC 4395. One light-year is the distance light travels in one year -- approximately six trillion miles.
Astronomers consider NGC 4395 to be an “active galaxy,” one with a very bright center, or nucleus. Current theory holds that black holes may literally be consuming active galactic nuclei (AGNs). Black holes in AGNs are supposed to be very massive.
NGC 4395 appears to be special, because the black hole in the center of the galaxy is much smaller than those found in other active galaxies, explained Ari Laor, professor of astronomy at the Technion, in Haifa, Israel, and Brad Peterson, professor of astronomy at Ohio State.
While astronomers have found much evidence of black holes that are larger than a million solar masses or smaller than a few tens of solar masses, they haven’t found as many midsize black holes -- ones on the scale of hundreds or thousands of solar masses.
Black holes such as the one in NGC 4395 provide a step in closing that gap.
Laor and Peterson and their colleagues used the Doppler radar-like technique to track the movement of gas around the center of NGC 4395. Whereas radar bounces a radio frequency signal off of an object, the astronomers observed light signals that naturally emanated from the center of the galaxy, and timed how long those signals took to reach the orbiting gas.
The method is called reverberation mapping, and Peterson’s team is among a small number of groups who are developing it as a reliable means of measuring black hole masses. The method works because gas orbits faster around massive black holes than it does around smaller ones.
Peterson reported the early results Saturday at the meeting of the American Association for the Advancement of Science in Washington, DC.
Two of the team members -- Luis Ho of the Observatories of the Carnegie Institution of Washington, and Alex Fillippenko of the University of California, Berkeley -- were the first to suspect that the black hole mass was very small. Filippenko and Wallace L.W. Sargent of the California Institute of Technology first discovered the black hole in 1989.
This is the first time astronomers have been able to measure the mass of the black hole in NGC 4395, and confirm that it is indeed smaller than others of its kind.
Peterson and Laor emphasized that the results are very preliminary, but the black hole seems to be at least a hundred times smaller than any other black hole ever detected inside an AGN.
The astronomers want to refine that estimate before they address the next most logical question: why is the black hole so small?
“Is it the runt of the litter, or did it just happen to form under special circumstances? We don’t know yet,” Peterson said.
NGC 4395 doesn’t appear to have a dense spherical nucleus, called a galactic bulge, at its center; it could be that the black hole “ate” all the stars in the bulge, and doesn’t have any more food within reach. That would keep the black hole from growing.
Team members are most interested in what the black hole measurement can tell astronomers about AGNs in general. Any new information could help astronomers better understand the role that black holes play in making galaxies like our own form and evolve. To that end, the team is also studying related data from NASA’s Chandra X-ray Observatory and ground-based telescopes.
“It’s these extreme types of objects that really allow you to test your theories,” Peterson said.
Adapted from materials provided by Ohio State University.
===========================================================
Black Hole Food
http://science.hq.nasa.gov/universe/science/black_holes.html
What Happens at the Edge of a Black Hole?
Overview Galaxies Stars Black Holes Astrobio Big Bang Dark Energy Fate
Don't let the name fool you: A black hole is anything but empty space. Rather, it is a great amount of matter packed into a very small area - think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City. The result is a gravitational field so strong that nothing, not even light, can escape. In recent years, NASA instruments have painted a new picture of these strange objects that are, to many, the most fascinating objects in space.
This star-studded infrared image from NASA's Spitzer Space Telescope shows the Milky Way's churning center. In this false-color image, old, cool stars appear blue, and the dust near hot, massive stars is red. Astronomers believe there is a supermassive black hole in the galaxy's core, visible here as a bright white spot. Credit: NASA/JPL-Caltech/S. Stolovy (SSC/Caltech). [+ more]
Although the term was not coined until 1967 by Princeton physicist John Wheeler, the idea of an object in space so massive and dense that light could not escape it has been around for centuries. Most famously, black holes were predicted by Einstein's theory of general relativity, which showed that when a massive star dies, it leaves behind a small, dense remnant core. If the core's mass is more than about three times the mass of the Sun, the equations showed, the force of gravity overwhelms all other forces and produces a black hole.
When a massive star runs out of fuel, as this animation shows, the core collapses and forms a black hole. Scientists long thought that the explosion would be followed by an afterglow of dying embers, but new evidence from the Swift telescope indicates that a newborn black hole somehow re-energizes the explosion again and again, creating multiple bursts of energy in a few minutes. Credit: NASA/GSFC/Dana Berry. [+ more]
Scientists can't directly observe black holes with telescopes that detect X-rays, light, or other forms of electromagnetic radiation. We can, however, infer the presence of black holes and study their effects on surrounding space with telescopes such as NASA's space-based Chandra X-ray Observatory. If a black hole passes through a cloud of interstellar matter, or is near a star, it will draw matter inward in a process known as accretion. As the attracted matter accelerates and heats up, it emits X-rays that radiate into space.
Recent discoveries offer some tantalizing evidence that black holes have a dramatic influence on surrounding space -- emitting powerful gamma ray bursts, devouring nearby stars, spurring the growth of new stars in some areas and stalling it in others.
One Star's End is a Black Hole's Beginning
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.) If the total mass of the star is large enough (about 3 times the mass of the sun), then it may be proven theoretically that no force can keep the star from collapsing under the influence of gravity. However, as the star collapses, a strange thing occurs. As the surface of the stars nears an imaginary surface called the "event horizon", time on the star slows down relative to the time kept by observers far away. When the surface reaches the event horizon, time stands still and the star may collapse no more. It is a frozen collapsing object.
Even bigger black holes can result from stellar collisions. Soon after its launch in December 2004, NASA's Swift telescope observed the powerful, fleeting flashes of light known as gamma ray bursts. Chandra and NASA's Hubble Space Telescope later collected data from the event's "afterglow," and together the observations led astronomers to conclude that the powerful explosions can result when a black hole and a neutron star collide, producing another black hole.
Babies and Giants
Although the basic formation process is understood, one perennial mystery in the science of black holes is that they appear to exist on two radically different size scales. On one end, there are the countless black holes that are the remnants of massive stars. Peppered throughout the universe, these "stellar mass" black holes are generally 10 to 20 times as massive as the Sun. Astronomers spot them when another star draws near enough for some of the matter surrounding it to be snared by the black hole's gravity, churning out X-rays in the process. Most stellar black holes, however, lead isolated lives and are impossible to detect. Judging from the number of stars large enough to produce such black holes, however, scientists estimate that there are as many as ten million to a billion such black holes in the Milky Way alone.
On the other side of the size spectrum are the beastly giants known as "supermassive" black holes, which are millions, if not billions, of times as massive as the Sun. Astronomers believe that supermassive black holes lie at the center of many large galaxies, even our own Milky Way. Astronomers can detect them by watching for the telltale ways they affect nearby stars and gas.
For decades, most researchers have believed that black holes came in two sizes: the mass of a few stars, or the mass of a million stars or more. These two previously undiscovered black holes provide an important link that sheds light on the way in which black holes grow. The black hole in M15 (left) is 4,000 times more massive than our Sun. G1 (right), a much larger globular cluster, harbors a heftier black hole, about 20,000 times more massive than our Sun. [+ more]
In 1997, the Hubble Space Telescope's was equipped with an instrument that separates visible light into various wavelengths, the Space Telescope Imaging Spectrograph (STIS). Measurements by STIS can reveal the speed and other properties of gas as it swirls into a black hole, which in turn reveals certain characteristics about the black hole itself - its mass, for example, and how fast it is spinning. It is these observations from Hubble that show that most, possibly all, large galaxies are home to a churning black hole. One black hole, 50 million light-years away in the constellation Virgo, has been calculated to have a mass equal to about three billion Suns.
The matter surrounding a stellar black hole - known as the accretion disk - is made of gas and dust. Around a supermassive black hole in the middle of a galaxy, this disk can include stars as well. In 2004, data from Chandra offered scientists their first-ever glimpse of a black hole shredding a nearby star.
This illustration shows two merging galaxies, an event that triggers a burst of star formation and provides fuel for the supermassive black holes in each galaxy's center. The inset shows a Chandra image of two central black holes -- about 70,000 light years apart - in merging galaxies. The varying colors represent differences in X-ray absorption by gas and dust around the black holes. Credit: CXC/M.Weiss. [+ more]
Later that year, Chandra spotted two supermassive black holes orbiting in the same galaxy - and therefore doomed to collide. And in October 2005, Chandra revealed a series of stars thought to have been spawned by the supermassive black hole at the center of the Milky Way.
The Future of Black Hole Science
So far, there has been no direct evidence for mid-sized black holes. The question is, why not? Historically, scientists have believed simply that no such black holes exist, but recent observations have led some astronomers to think otherwise. The question of whether black holes of intermediate mass exist is a subject of much current research.
The current generation of space-based telescopes do not possess the resolution to directly image mass falling into a black hole, but NASA hopes that future instruments will. The Black Hole Imager mission will detect high-frequency radio waves and X-rays emitted during accretion - the process by which a black hole sucks matter inward - to measure the properties of gas as it swirls into black holes. Astronomers hope to test some of the more exotic predictions of general relativity theory by comparing to these direct measurements of accretion.
The Black Hole Imager is part of NASA's ambitious "Beyond Einstein" program, which will take a census of black holes in the Universe and provide detailed pictures of what happens in the surrounding regions of space. In tandem with the Black Hole Imager, four X-ray telescopes comprising the Constellation-X observatory be 100 times more sensitive than any previous X-ray satellite mission. As a result, scientists will collect unprecedented amounts of data in a fraction of the time it would take with current X-ray telescopes such as Chandra.
Another key mission, LISA, will look for black holes in a completely different way. In a sense, looking at the accretion disk around a black hole is not really seeing the black hole itself. A black hole is the mass it contains plus the intense gravitational field around it. When two black holes orbit each other, their accelerated masses directly create gravitational waves that stream away through space and carry information about the masses and strong fields that created them. Gravitational waves are waves of space curvature and may be detected by missions such as LISA through the way they affect the geometry of space at the location of the detector. LISA will "see" black holes.
Are there intermediate-mass black holes? Do the supermassive black holes at galactic nuclei grow by accretion? Do nuclear black holes precede and act as seeds for the formation of galaxies or are they formed after the galaxy as it collapses toward its dynamical center? Do all galaxies contain black holes? Do the mergers of galaxies and the subsequent coalescence of their black holes contribute to galactic evolution? These questions and more will be answered by the Beyond Einstein Mission suite. But there is also one thing you may be sure of when you open up a new window on the Universe. There will be surprises and more questions to ask.
Greedy Supermassive Black Holes Dislike Dark Matter
What Happens at the Edge of a Black Hole?
Overview Galaxies Stars Black Holes Astrobio Big Bang Dark Energy Fate
Don't let the name fool you: A black hole is anything but empty space. Rather, it is a great amount of matter packed into a very small area - think of a star ten times more massive than the Sun squeezed into a sphere approximately the diameter of New York City. The result is a gravitational field so strong that nothing, not even light, can escape. In recent years, NASA instruments have painted a new picture of these strange objects that are, to many, the most fascinating objects in space.
This star-studded infrared image from NASA's Spitzer Space Telescope shows the Milky Way's churning center. In this false-color image, old, cool stars appear blue, and the dust near hot, massive stars is red. Astronomers believe there is a supermassive black hole in the galaxy's core, visible here as a bright white spot. Credit: NASA/JPL-Caltech/S. Stolovy (SSC/Caltech). [+ more]
Although the term was not coined until 1967 by Princeton physicist John Wheeler, the idea of an object in space so massive and dense that light could not escape it has been around for centuries. Most famously, black holes were predicted by Einstein's theory of general relativity, which showed that when a massive star dies, it leaves behind a small, dense remnant core. If the core's mass is more than about three times the mass of the Sun, the equations showed, the force of gravity overwhelms all other forces and produces a black hole.
When a massive star runs out of fuel, as this animation shows, the core collapses and forms a black hole. Scientists long thought that the explosion would be followed by an afterglow of dying embers, but new evidence from the Swift telescope indicates that a newborn black hole somehow re-energizes the explosion again and again, creating multiple bursts of energy in a few minutes. Credit: NASA/GSFC/Dana Berry. [+ more]
Scientists can't directly observe black holes with telescopes that detect X-rays, light, or other forms of electromagnetic radiation. We can, however, infer the presence of black holes and study their effects on surrounding space with telescopes such as NASA's space-based Chandra X-ray Observatory. If a black hole passes through a cloud of interstellar matter, or is near a star, it will draw matter inward in a process known as accretion. As the attracted matter accelerates and heats up, it emits X-rays that radiate into space.
Recent discoveries offer some tantalizing evidence that black holes have a dramatic influence on surrounding space -- emitting powerful gamma ray bursts, devouring nearby stars, spurring the growth of new stars in some areas and stalling it in others.
One Star's End is a Black Hole's Beginning
Most black holes form from the remnants of a large star that dies in a supernova explosion. (Smaller stars become dense neutron stars, which are not massive enough to trap light.) If the total mass of the star is large enough (about 3 times the mass of the sun), then it may be proven theoretically that no force can keep the star from collapsing under the influence of gravity. However, as the star collapses, a strange thing occurs. As the surface of the stars nears an imaginary surface called the "event horizon", time on the star slows down relative to the time kept by observers far away. When the surface reaches the event horizon, time stands still and the star may collapse no more. It is a frozen collapsing object.
Even bigger black holes can result from stellar collisions. Soon after its launch in December 2004, NASA's Swift telescope observed the powerful, fleeting flashes of light known as gamma ray bursts. Chandra and NASA's Hubble Space Telescope later collected data from the event's "afterglow," and together the observations led astronomers to conclude that the powerful explosions can result when a black hole and a neutron star collide, producing another black hole.
Babies and Giants
Although the basic formation process is understood, one perennial mystery in the science of black holes is that they appear to exist on two radically different size scales. On one end, there are the countless black holes that are the remnants of massive stars. Peppered throughout the universe, these "stellar mass" black holes are generally 10 to 20 times as massive as the Sun. Astronomers spot them when another star draws near enough for some of the matter surrounding it to be snared by the black hole's gravity, churning out X-rays in the process. Most stellar black holes, however, lead isolated lives and are impossible to detect. Judging from the number of stars large enough to produce such black holes, however, scientists estimate that there are as many as ten million to a billion such black holes in the Milky Way alone.
On the other side of the size spectrum are the beastly giants known as "supermassive" black holes, which are millions, if not billions, of times as massive as the Sun. Astronomers believe that supermassive black holes lie at the center of many large galaxies, even our own Milky Way. Astronomers can detect them by watching for the telltale ways they affect nearby stars and gas.
For decades, most researchers have believed that black holes came in two sizes: the mass of a few stars, or the mass of a million stars or more. These two previously undiscovered black holes provide an important link that sheds light on the way in which black holes grow. The black hole in M15 (left) is 4,000 times more massive than our Sun. G1 (right), a much larger globular cluster, harbors a heftier black hole, about 20,000 times more massive than our Sun. [+ more]
In 1997, the Hubble Space Telescope's was equipped with an instrument that separates visible light into various wavelengths, the Space Telescope Imaging Spectrograph (STIS). Measurements by STIS can reveal the speed and other properties of gas as it swirls into a black hole, which in turn reveals certain characteristics about the black hole itself - its mass, for example, and how fast it is spinning. It is these observations from Hubble that show that most, possibly all, large galaxies are home to a churning black hole. One black hole, 50 million light-years away in the constellation Virgo, has been calculated to have a mass equal to about three billion Suns.
The matter surrounding a stellar black hole - known as the accretion disk - is made of gas and dust. Around a supermassive black hole in the middle of a galaxy, this disk can include stars as well. In 2004, data from Chandra offered scientists their first-ever glimpse of a black hole shredding a nearby star.
This illustration shows two merging galaxies, an event that triggers a burst of star formation and provides fuel for the supermassive black holes in each galaxy's center. The inset shows a Chandra image of two central black holes -- about 70,000 light years apart - in merging galaxies. The varying colors represent differences in X-ray absorption by gas and dust around the black holes. Credit: CXC/M.Weiss. [+ more]
Later that year, Chandra spotted two supermassive black holes orbiting in the same galaxy - and therefore doomed to collide. And in October 2005, Chandra revealed a series of stars thought to have been spawned by the supermassive black hole at the center of the Milky Way.
The Future of Black Hole Science
So far, there has been no direct evidence for mid-sized black holes. The question is, why not? Historically, scientists have believed simply that no such black holes exist, but recent observations have led some astronomers to think otherwise. The question of whether black holes of intermediate mass exist is a subject of much current research.
The current generation of space-based telescopes do not possess the resolution to directly image mass falling into a black hole, but NASA hopes that future instruments will. The Black Hole Imager mission will detect high-frequency radio waves and X-rays emitted during accretion - the process by which a black hole sucks matter inward - to measure the properties of gas as it swirls into black holes. Astronomers hope to test some of the more exotic predictions of general relativity theory by comparing to these direct measurements of accretion.
The Black Hole Imager is part of NASA's ambitious "Beyond Einstein" program, which will take a census of black holes in the Universe and provide detailed pictures of what happens in the surrounding regions of space. In tandem with the Black Hole Imager, four X-ray telescopes comprising the Constellation-X observatory be 100 times more sensitive than any previous X-ray satellite mission. As a result, scientists will collect unprecedented amounts of data in a fraction of the time it would take with current X-ray telescopes such as Chandra.
Another key mission, LISA, will look for black holes in a completely different way. In a sense, looking at the accretion disk around a black hole is not really seeing the black hole itself. A black hole is the mass it contains plus the intense gravitational field around it. When two black holes orbit each other, their accelerated masses directly create gravitational waves that stream away through space and carry information about the masses and strong fields that created them. Gravitational waves are waves of space curvature and may be detected by missions such as LISA through the way they affect the geometry of space at the location of the detector. LISA will "see" black holes.
Are there intermediate-mass black holes? Do the supermassive black holes at galactic nuclei grow by accretion? Do nuclear black holes precede and act as seeds for the formation of galaxies or are they formed after the galaxy as it collapses toward its dynamical center? Do all galaxies contain black holes? Do the mergers of galaxies and the subsequent coalescence of their black holes contribute to galactic evolution? These questions and more will be answered by the Beyond Einstein Mission suite. But there is also one thing you may be sure of when you open up a new window on the Universe. There will be surprises and more questions to ask.
Greedy Supermassive Black Holes Dislike Dark Matter
Written by Ian O'Neill
It is widely accepted that supermassive black holes (SMBHs) sit in the centre of elliptical galaxies or bulges of spiral galaxies. They suck in as much matter as possible, generating blasts of radiation. Stars, gas and everything else nearby forms a compact "halo" and then falls to a gravitationally enforced death spiral. The greedy nature and the sheer size of these black holes have led to the idea that dark matter may supply (or may have supplied) the SMBH with some mass during its evolution. But could it be that dark matter may not be significantly involved after all? This might be one cosmic phenomenon dark matter can't be blamed for.Black hole accretion disks are compact halos created as dust, gas and other debris are pulled toward a black hole event horizon. Accretion disks radiate electromagnetic radiation, and the frequency of which depends on the mass of the black hole. The more massive it is, the higher the energy of radiation emitted into space. In the case of a SMBH, the huge mass causes very bright emission as the matter from the accretion disk falls into the event horizon (the point at which gravity becomes so strong that even light cannot escape). As accretion disk matter falls toward the event horizon, approximately 10% of the mass is converted into energy and ejected as X-rays. This is a far more efficient energy conversion rate than the most efficient nuclear fusion reaction (approximately 0.5%). This X-ray emission can then be observed, creating a quasar, signifying a SMBH is driving the active galaxy.Interestingly, an SMBH is not thought to be formed from single dead massive star. They are thought to have been created from a "seed" and then grown over billions of years. The source of the mass feeding the growing SMBH comes from its accretion disk, but it is uncertain what form the matter comes in and at what rate it "feeds" the black hole. There are several possibilities as to how the largest black holes were seeded, but two are the most widely accepted:a.. Intermediate black holes (with masses of several thousand Suns) are created by vast clouds which collapse to a single point. Black holes form and accretion disks grow. b.. Massive primordial stars (the first stars, formed only 200 million years after the Big Bang) of a few hundred Sun masses may have collapsed to create smaller black holes, again forming accretion disks and growing over billions of years. The mechanisms affecting the rate of accretion disk growth are not so clear-cut. Some theories suggest that huge quantities (most of the black hole mass) comes from dark matter. However, as dark matter is "non-baryonic" (i.e. the opposite to baryonic matter - the matter we know, love and observe in our universe) it will emit very little radiation as it falls into the black hole event horizon. If this is the case, SMBHs would grow disproportionately when compared with radiation emitted from galactic centres (only baryonic particles will emit X-rays).New research headed by Sebastien Peirani (at the Institut d'Astrophysique de Paris, France) suggests only a very small fraction of a SMBH is composed from dark matter as it evolved. Dark matter is predicted to be collisionless and will be scattered very easily by baryonic gas clouds and stars. It seems unlikely that dark matter will be able to stay inside the black hole's accretion disk for very long before it is repelled by all the "normal" matter being pulled toward the event horizon.
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