X-Rays Emanate From Heated Material Falling Into Black Hole
Astronomers unveiled the deepest images from NASA's new Spitzer Space Telescope today, and announced the detection of distant objects — including several supermassive black holes — that are nearly invisible in even the deepest images from telescopes operating at other wavelengths.
Dr. Mark Dickinson, of the National Optical Astronomy Observatory, Tucson, Ariz., and principal investigator for the new observations, said, "With these ultra-deep Spitzer images, we are easily seeing objects throughout time and space, out to redshifts of 6 or more, where the most distant known galaxies lie. Moreover, we see some objects that are completely invisible, but whose existence was hinted at by previous observations from the Chandra and Hubble Observatories."
Seven of the objects detected by Spitzer may be part of the long-sought population of "missing" supermassive black holes that powered the bright cores of the earliest active galaxies. The discovery completes a full accounting of all the X-ray sources seen in one of the deepest surveys of the universe ever taken.
This detective story required the combined power of NASA's three orbiting Great Observatories — the Hubble Space Telescope, Chandra X-ray Observatory, and Spitzer Space Telescope. Each observatory works with different wavelengths of electromagnetic radiation, from high-energy X-rays with Chandra, through visible light with Hubble, and into the infrared with Spitzer. Together, these telescopes yield far more information than any single instrument.
All three telescopes peered out to distances of up to 13 billion light-years toward a small patch of the southern sky containing more than 10,000 galaxies, in a coordinated project called the Great Observatories Origins Deep Survey (GOODS). Chandra images detected more than 200 hundred X-ray sources believed to be supermassive black holes in the centers of young galaxies. The X-rays are produced by extremely hot interstellar gases falling into the black holes.
Hubble's Advanced Camera for surveys revealed optical galaxies around almost all the X-ray black holes. However, there remained seven mysterious X-ray sources for which there was no optical galaxy. Dr. Anton Koekemoer of the Space Telescope Science Institute, Baltimore, Md., who discovered these sources, presented three intriguing possibilities for their origin.
STIS Records a Black Hole's Signature
The colorful "zigzag" on the right is not the work of a flamboyant artist, but the signature of a supermassive black hole in the center of galaxy M84, discovered by Hubble Space Telescope's Space Telescope Imaging Spectrograph (STIS).
The image on the left, taken with Hubble's Wide Field Planetary and Camera 2 shows the core of the galaxy where the suspected black hole dwells. Astronomers mapped the motions of gas in the grip of the black hole's powerful gravitational pull by aligning the STIS's spectroscopic slit across the nucleus in a single exposure.
The STIS data on the right shows the rotational motion of stars and gas along the slit. The change in wavelength records whether an object is moving toward or away from the observer. The larger the excursion from the centerline — as seen as a green and yellow picture element (pixels) along the center strip, the greater the rotational velocity. If no black hole were present, the line would be nearly vertical across the scan.
Instead, STIS's detector found the S-shape at the center of this scan, indicating a rapidly swirling disk of trapped material encircling the black hole. Along the S-shape from top to bottom, velocities skyrocket as seen in the rapid, dramatic swing to the left (blueshifted or approaching gas), then the region in the center simultaneously records the enormous speeds of the gas both approaching and receding for orbits in the immediate vicinity of the black hole, and then an equivalent swing from the right, back to the center line.
STIS measures a velocity of 880,000 miles per hour (400 kilometers per second) within 26 light-years of the galaxy's center, where the black hole dwells. This motion allowed astronomers to calculate that the black hole contains at least 300 million solar masses. (Just as the mass of our Sun can be calculated from the orbital radii and speeds of the planets.)
This observation demonstrates a direct connection between a supermassive black hole and activity (such as radio emission) in the nucleus of an active galaxy. It also shows that STIS is ideally suited for efficiently conducting a survey of galaxies to determine the distribution of the black holes and their masses.
Ring Around a Suspected Black Hole in Galaxy NGC 4261
The gravitational pull of a suspected super-massive black hole forms a frisbee-like disk of cool gas, at the core of an energetic galaxy. Subsequent Hubble observations of yet another active galaxy (M87) confirmed the reality of monstrous black holes — gravitational "sink holes" that trap everything, even light.
Resembling a gigantic hubcap in space, a 3,700-light-year-wide dust disk encircles a 300-million- solar-mass black hole in the center of the elliptical galaxy NGC 7052.
The disk, possibly a remnant of an ancient galaxy collision, will be swallowed up by the black hole in several billion years. The black-and-white image on the left, taken by a ground-based telescope, shows the complete galaxy. The Hubble picture on the right is a close-up view of the dust disk surrounding the black hole.
Hubble Uncovers Dust Disk around a Massive Black Hole
Resembling a gigantic hubcap in space, a 3,700-light-year-wide dust disk encircles a 300-million- solar-mass black hole in the center of the elliptical galaxy NGC 7052.
The disk, possibly a remnant of an ancient galaxy collision, will be swallowed up by the black hole in several billion years. The black-and-white image on the left, taken by a ground-based telescope, shows the complete galaxy. The Hubble picture on the right is a close-up view of the dust disk surrounding the black hole.
Hubble Discovers Black Holes in Unexpected Places
These two globular star clusters, M15 and G1, harbor hundreds of thousands of stars. But deep within their dense cores is an unexpected guest: a class of intermediate-sized black holes. Black holes are invisible, but the probing eye of NASA's Hubble Space Telescope found them by measuring the velocities of stars whirling around the crowded cores. Using spectral observations, astronomers discovered that the stars orbiting the cores of M15 and G1 moved at a much faster rate, which suggested the presence of unseen massive bodies. These previously undiscovered black holes provide an important link that sheds light on the way in which black holes grow.
The new findings promise a better understanding of how galaxies and globular clusters first formed billions of years ago. Globular star clusters contain the oldest stars in the universe. If these clusters have black holes now, then they most likely had black holes when they formed billions of years ago.
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.
The globular star cluster M15 resides 32,000 light-years away in the constellation Pegasus. M15 is one of nearly 150 known globular clusters that form a vast halo surrounding our Milky Way galaxy. G1, located 2.2 million light-years away in the neighboring Andromeda galaxy (also known as M31), has a total mass of 10 million suns, making it one of the most massive globular clusters known.
The Hubble telescope photograph of M15 was taken December 1998 by the Wide Field and Planetary Camera 2. Hubble's Wide Field and Planetary Camera 2 also snapped the image of G1, in July 1994.
The members of the G1 research team are Michael Rich (University of California, Los Angeles/UCLA), Karl Gebhardt (University of Texas at Austin), and Luis Ho (Carnegie Institute of Washington). The members of the M15 research team are Roeland Van Der Marel and Joris Gerssen (Space Telescope Science Institute), Karl Gebhardt, Puragra Guhathakurta and Ruth Peterson (UCO/Lick Observatory, University of California at Santa Cruz), and Carlton Pryor (Rutgers University).
Giant Disk of Cold Gas and Dust Fuels Possible Black Hole at Core of NGC 4261
Astronomers using NASA's Hubble Space Telescope (HST) have gotten their best look yet at the disk of material that surrounds and is being pulled into a suspected black hole.
The disk is at the core of a galaxy in the Virgo Cluster 45 million light-years from Earth. Dr. Walter Jaffe of Leiden Observatory in The Netherlands said the disk is tipped about 60 degrees — enough to provide astronomers with a clear view of the galaxy's bright hub.The nucleus is probably the home of a black hole with a mass 10 million times that of our Sun, Jaffe said. "This is our best view to date of the immediate surrounding of the nucleus of an active galaxy," the name given galaxies that emit especially strong radiation indicating that they harbor powerful energy sources.
This is the first case where we can follow the disk's gas in an orderly way down to the immediate environment of the black hole, said co-investigator Dr. Holland Ford of The Johns Hopkins University in Baltimore, Maryland.
The observations made with the Wide Field/Planetary Camera (WFIPC) in PC mode make a strong contribution to mounting evidence for the existence of black holes in the universe, the two astronomers said.
A black hole is a theoretical object which forms after a massive stars collapses. The star's matter is so densely compacted that it has a powerful gravitational pull that traps all matter that comes near it.
The observations made with the Wide Field/Planetary Camera (WFIPC) in PC mode make a strong contribution to mounting evidence for the existence of black holes in the universe, the two astronomers said.
A black hole is a theoretical object which forms after a massive stars collapses. The star's matter is so densely compacted that it has a powerful gravitational pull that traps all matter that comes near it.
Black holes are to date theoretical because their gravitational pull is so great that not even light can escape. Therefore, they cannot be seen. Astronomers can only infer a black hole's existence by its gravitational influence on the motion of stars and other material near it.
The galaxy, designated NGC 4261, was selected for study because it is one of the brightest in the Virgo Cluster.
The galaxy is unremarkable in visible light, said Jaffe. "However, observations with radio telescopes show a pair of opposed jets emanating from the nucleus and spanning a distance of 88,000 light-years." Spectroscopic data (from the Observatory del Roque de los Muchachos in the Canary Islands) show ionized gas in the nucleus moving at speeds approaching several million miles an hour, or one percent of the speed of light.
The galaxy, designated NGC 4261, was selected for study because it is one of the brightest in the Virgo Cluster.
The galaxy is unremarkable in visible light, said Jaffe. "However, observations with radio telescopes show a pair of opposed jets emanating from the nucleus and spanning a distance of 88,000 light-years." Spectroscopic data (from the Observatory del Roque de los Muchachos in the Canary Islands) show ionized gas in the nucleus moving at speeds approaching several million miles an hour, or one percent of the speed of light.
Most astronomers believe both phenomena, which have been seen earlier in radio galaxies and quasars (active nuclei of remote galaxies), to be caused by material being swallowed by massive black holes hiding in the nuclei of large galaxies, said Ford.
Fireworks Near a Black Hole in the Core of Seyfert Galaxy NGC 4151
The Space Telescope Imaging Spectrograph (STIS) simultaneously records, in unprecedented detail, the velocities of hundreds of gas knots streaming at hundreds of thousands of miles per hour from the nucleus of NGC 4151, thought to house a supermassive black hole.
This is the first time the velocity structure in the heart of this object, or similar objects, has been mapped so vividly this close to its central black hole.
The twin cones of gas emission are powered by the energy released from the supermassive black hole believed to reside at the heart of this Seyfert galaxy. The STIS data clearly show that the gas knots illuminated by one of these cones is rapidly moving towards us, while the gas knots illuminated by the other cone are rapidly receding.
This is the first time the velocity structure in the heart of this object, or similar objects, has been mapped so vividly this close to its central black hole.
The twin cones of gas emission are powered by the energy released from the supermassive black hole believed to reside at the heart of this Seyfert galaxy. The STIS data clearly show that the gas knots illuminated by one of these cones is rapidly moving towards us, while the gas knots illuminated by the other cone are rapidly receding.
The images have been rotated to show the same orientation of NGC 4151. The figures show:
WFPC2 (upper left) — A Hubble Wide Field Planetary Camera 2 image of the oxygen emission (5007 Angstroms) from the gas at the heart of NGC 4151. Though the twin cone structure can be seen, the image does not provide any information about the motion of the oxygen gas.
STIS OPTICAL (upper right) — In this STIS spectral image of the oxygen gas, the velocities of the knots are determined by comparing the knots of gas in the stationary WFPC2 image to the horizontal location of the knots in the STIS image.
STIS OPTICAL (lower right) — In this false color image the two emission lines of oxygen gas (the weaker one at 4959 Angstroms and the stronger one at 5007 Angstroms) are clearly visible. The horizontal line passing through the image is from the light generated by the powerful black hole at the center of NGC 4151.
WFPC2 (upper left) — A Hubble Wide Field Planetary Camera 2 image of the oxygen emission (5007 Angstroms) from the gas at the heart of NGC 4151. Though the twin cone structure can be seen, the image does not provide any information about the motion of the oxygen gas.
STIS OPTICAL (upper right) — In this STIS spectral image of the oxygen gas, the velocities of the knots are determined by comparing the knots of gas in the stationary WFPC2 image to the horizontal location of the knots in the STIS image.
STIS OPTICAL (lower right) — In this false color image the two emission lines of oxygen gas (the weaker one at 4959 Angstroms and the stronger one at 5007 Angstroms) are clearly visible. The horizontal line passing through the image is from the light generated by the powerful black hole at the center of NGC 4151.
STIS ULTRAVIOLET (lower left) — This STIS spectral image shows the velocity distribution of the carbon emission from the gas in the core of NGC 4151. It requires more energy to make the carbon gas glow (CIV at 1549 Angstroms) than it does to ionize the oxygen gas seen in the other images. This means we expect that the carbon emitting gas is closer to the heart of the energy source.
Feasting Black Hole Blows Bubbles
A monstrous black hole's rude table manners include blowing huge bubbles of hot gas into space. At least, that's the gustatory practice followed by the supermassive black hole residing in the hub of the nearby galaxy NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC 4438 is in the Virgo Cluster, 50 million light-years from Earth.
These NASA Hubble Space Telescope images of the galaxy's central region clearly show one of the bubbles rising from a dark band of dust. The other bubble, emanating from below the dust band, is barely visible, appearing as dim red blobs in the close-up picture of the galaxy's hub (the colorful picture at right). The background image represents a wider view of the galaxy, with the central region defined by the white box.
These extremely hot bubbles are caused by the black hole's voracious eating habits. The eating machine is engorging itself with a banquet of material swirling around it in an accretion disk (the white region below the bright bubble). Some of this material is spewed from the disk in opposite directions. Acting like high-powered garden hoses, these twin jets of matter sweep out material in their paths. The jets eventually slam into a wall of dense, slow-moving gas, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The bubbles will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this bubble-blowing phase is a short-lived event.
These NASA Hubble Space Telescope images of the galaxy's central region clearly show one of the bubbles rising from a dark band of dust. The other bubble, emanating from below the dust band, is barely visible, appearing as dim red blobs in the close-up picture of the galaxy's hub (the colorful picture at right). The background image represents a wider view of the galaxy, with the central region defined by the white box.
These extremely hot bubbles are caused by the black hole's voracious eating habits. The eating machine is engorging itself with a banquet of material swirling around it in an accretion disk (the white region below the bright bubble). Some of this material is spewed from the disk in opposite directions. Acting like high-powered garden hoses, these twin jets of matter sweep out material in their paths. The jets eventually slam into a wall of dense, slow-moving gas, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The bubbles will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this bubble-blowing phase is a short-lived event.
The bubble is much brighter on one side of the galaxy's center because the jet smashed into a denser amount of gas. The brighter bubble is 800 light-years tall and 800 light-years across.
The observations are being presented June 5 at the American Astronomical Society meeting in Rochester, N.Y. Both pictures were taken March 24, 1999 with the Wide Field and Planetary Camera 2. False colors were used to enhance the details of the bubbles. The red regions in the picture denote the hot gas.
Black Hole's Disk is Flooded With Ultraviolet Light
NASA's Hubble Space Telescope has provided a never-before-seen view of a warped disk flooded with a torrent of ultraviolet light from hot gas trapped around a suspected massive black hole.
[Right]
This composite image of the core of the galaxy was constructed by combining a visible light image taken with Hubble's Wide Field Planetary Camera 2 (WFPC2), with a separate image taken in ultraviolet light with the Faint Object Camera (FOC). While the visible light image shows a dark dust disk, the ultraviolet image (color-coded blue) shows a bright feature along one side of the disk. Because Hubble sees ultraviolet light reflected from only one side of the disk, astronomers conclude the disk must be warped like the brim of a hat. The bright white spot at the image's center is light from the vicinity of the black hole which is illuminating the disk.
[Right]
This composite image of the core of the galaxy was constructed by combining a visible light image taken with Hubble's Wide Field Planetary Camera 2 (WFPC2), with a separate image taken in ultraviolet light with the Faint Object Camera (FOC). While the visible light image shows a dark dust disk, the ultraviolet image (color-coded blue) shows a bright feature along one side of the disk. Because Hubble sees ultraviolet light reflected from only one side of the disk, astronomers conclude the disk must be warped like the brim of a hat. The bright white spot at the image's center is light from the vicinity of the black hole which is illuminating the disk.
[Left]
A ground-based telescopic view of the core of the elliptical galaxy NGC 6251. The inset box shows Hubble Space Telescope's field of view. The galaxy is 300 million light-years away in the constellation Ursa Minor.
A ground-based telescopic view of the core of the elliptical galaxy NGC 6251. The inset box shows Hubble Space Telescope's field of view. The galaxy is 300 million light-years away in the constellation Ursa Minor.
