There’s jumbo shrimp and accurate rumors; now there’s even a mini supermassive black hole. Astronomers have identified the smallest supermassive black hole ever observed, and while it’s considered a shrimp as far as supermassive black holes go, this guy is still pretty big: the mass of the black hole in galaxy NGC 4178 is estimated to be about 200,000 times the mass of our Sun. But it was a surprise that this galaxy had a black hole at all.
Astronomers using the Chandra X-Ray Observatory in conjunction with other observatories took a look at NGC 4178, a late-type spiral galaxy located about 55 million light years from Earth. It does not contain a bright central concentration, or bulge, of stars in its center, and so it was thought that perhaps this galaxy was one of the few that didn’t harbor a black hole.
With using Chandra’s X-Ray vision, as well as infrared data the NASA’s Spitzer Space Telescope and radio data from the Very Large Array, Nathan Secrest, from George Mason University and his team identified a weak X-ray source at the center of the galaxy, and also saw varying brightness at infrared wavelengths, suggesting that a black hole was actually in the center of NGC 4178 and was pulling in material from its surroundings. The same data also suggested that light generated by this infalling material is heavily absorbed by gas and dust and was therefore surrounding a black hole.
They were able to estimate the size of the black hole by using the known relationship between the mass of a black hole and the amount of X-rays and radio waves it generates.
While this is the lowest mass supermassive black holes ever observed, astronomers admit this is probably near the extreme low-mass end of being in the “supermassive” range. And as the team pointed out in their paper, there is increasing evidence that several late-type galaxies do host supermassive black holes, and that a classical bulge is not a requirement for a supermassive black hole to form and grow.
Artist's impression of the huge halo of hot gas surrounding the Milky Way Galaxy. Credit: NASA
Artist’s illustration of a hot gas halo enveloping the Milky Way and Magellanic Clouds (NASA/CXC/M.Weiss; NASA/CXC/Ohio State/A.Gupta et al.)
Our galaxy — and the nearby Large and Small Magellanic Clouds as well — appears to be surrounded by an enormous halo of hot gas, several hundred times hotter than the surface of the Sun and with an equivalent mass of up to 60 billion Suns, suggesting that other galaxies may be similarly encompassed and providing a clue to the mystery of the galaxy’s missing baryons.
In the artist’s rendering above our Milky Way galaxy is seen at the center of a cloud of hot gas. This cloud has been detected in measurements made with Chandra as well as with the European Space Agency’s XMM-Newton space observatory and Japan’s Suzaku satellite. The illustration shows it to extend outward over 300,000 light-years — and it may actually be even bigger than that.
While observing bright x-ray sources hundreds of millions of light-years distant, the researchers found that oxygen ions in the immediate vicinity of our galaxy were “selectively absorbing” some of the x-rays. They were then able to measure the temperature of the halo of gas responsible for the absorption.
The scientists determined the temperature of the halo is between 1 million and 2.5 million kelvins — a few hundred times hotter than the surface of the Sun.
But even with an estimated mass anywhere between 10 billion and 60 billion Suns, the density of the halo at that scale is still so low that any similar structure around other galaxies would escape detection. Still, the presence of such a large halo of hot gas, if confirmed, could reveal where the missing baryonic matter in our galaxy has been hiding — a mystery that’s been plaguing astronomers for over a decade.
Unrelated to dark matter or dark energy, the missing baryons issue was discovered when astronomers estimated the number of atoms and ions that would have been present in the Universe 10 billion years ago. But current measurements yield only about half as many as were present 10 billion years ago, meaning somehow nearly half the baryonic matter in the Universe has since disappeared.
Recent studies have proposed that the missing matter is tied up in the comic web — vast clouds and strands of gas and dust that surround and connect galaxies and galactic clusters. The findings announced today from Chandra support this, and suggest that the missing ions could be gathered around other galaxies in similarly hot halos.
Even though previous studies have indicated halos of warm gas existing around our galaxy as well as others, this new research shows a much hotter, much more massive halo than ever detected.
“Our work shows that, for reasonable values of parameters and with reasonable assumptions, the Chandra observations imply a huge reservoir of hot gas around the Milky Way,” said study co-author Smita Mathur of Ohio State University in Columbus. “It may extend for a few hundred thousand light-years around the Milky Way or it may extend farther into the surrounding local group of galaxies. Either way, its mass appears to be very large.”
Read the full news release from NASA here, and learn more about the Chandra mission here. (The team’s paper can be found on arXiv.org.)
NOTE: the initial posting of this story mentioned that this halo could be dark matter. That was incorrect and not implied by the actual research, as dark matter is non-baryonic matter while the hot gas in the halo is baryonic — i.e., “normal” — matter. Edited. – JM
A pulsar may have been spotted racing through space at over 6 million miles per hour (9.65 million km/h), setting a new speed record for these curious cosmic objects. If observations are what they appear to be, astronomers will have to recalculate the incredible forces created by supernova explosions.
Seen in observations made with 3 different telescopes — NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, and the Parkes radio telescope in Australia — the x-ray-emitting object IGR J11014-6103 appears to be racing away from the remnants of a supernova in the constellation Carina, 30,000 light-years from Earth.
The comet-shaped object is thought to be a pulsar, the rapidly-spinning, superdense remains of a star. The facts that it’s dim in optical and infrared wavelengths and hasn’t changed in x-ray brightness between XMM-Newton observations in 2003 and Chandra measurements in 2011 support the claim.
IGR J11014’s comet-like shape may be the result of its breakneck speed through space as its pulsar wind nebula gets blown back by the high-energy bow shock created at the forefront of its passage.
Pulsar wind nebulae are the results of charged particles streaming out from the pulsar itself. The particles, traveling at nearly light-speed, are rapidly decelerated by the interstellar medium and create a visible shock wave. In the case of IGR J11014, the pulsar wind is formed into a “tail” by its bow shock — effectively a sonic boom in front of it.
Further observations will be needed to confirm that IGR J11014 is indeed a pulsar, especially considering that actual pulsations have not yet been detected. If it is a pulsar, and is really traveling at the record-breaking speeds it appears to be — between 5.4 and 6.5 million miles per hour, more than 12 times faster than the Sun travels around the center of the galaxy — a new model of supernova explosions may be required.
New evidence from NASA’s Chandra X-ray Observatory challenges prevailing ideas about how black holes grow in the centers of galaxies. Astronomers long have thought that a supermassive black hole and the bulge of stars at the center of its host galaxy grow at the same rate — the bigger the bulge, the bigger the black hole. However, a new study of Chandra data has revealed two nearby galaxies with supermassive black holes that are growing faster than the galaxies themselves.
The mass of a giant black hole at the center of a galaxy typically is a tiny fraction — about 0.2 percent — of the mass contained in the bulge, or region of densely packed stars, surrounding it. The targets of the latest Chandra study, galaxies NGC 4342 and NGC 4291, have black holes 10 times to 35 times more massive than they should be compared to their bulges. The new observations with Chandra show the halos, or massive envelopes of dark matter in which these galaxies reside, also are overweight.
This study suggests the two supermassive black holes and their evolution are tied to their dark matter halos and did not grow in tandem with the galactic bulges. In this view, the black holes and dark matter halos are not overweight, but the total mass in the galaxies is too low.
“This gives us more evidence of a link between two of the most mysterious and darkest phenomena in astrophysics — black holes and dark matter — in these galaxies,” said Akos Bogdan of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., who led the new study.
NGC 4342 and NGC 4291 are close to Earth in cosmic terms, at distances of 75 million and 85 million light years. Astronomers had known from previous observations that these galaxies host black holes with relatively large masses, but are not certain what is responsible for the disparity. Based on the new Chandra observations, however, they are able to rule out a phenomenon known as tidal stripping.
Tidal stripping occurs when some of a galaxy’s stars are stripped away by gravity during a close encounter with another galaxy. If such tidal stripping had taken place, the halos mostly would have been missing. Because dark matter extends farther away from the galaxies, it is more loosely tied to them than the stars and more likely to be pulled away.
To rule out tidal stripping, astronomers used Chandra to look for evidence of hot, X-ray-emitting gas around the two galaxies. Because the pressure of hot gas — estimated from X-ray images — balances the gravitational pull of all the matter in the galaxy, the new Chandra data can provide information about the dark matter halos. The hot gas was found to be distributed widely around NGC 4342 and NGC 4291, implying that each galaxy has an unusually massive dark matter halo and that tidal stripping is unlikely.
“This is the clearest evidence we have, in the nearby universe, for black holes growing faster than their host galaxy,” said co-author Bill Forman, also of CfA. “It’s not that the galaxies have been compromised by close encounters, but instead they had some sort of arrested development.”
How can the mass of a black hole grow faster than the stellar mass of its host galaxy? The study’s authors suggest a large concentration of gas spinning slowly in the galactic center is what the black hole consumes very early in its history. It grows quickly, and as it grows, the amount of gas it can accrete, or swallow, increases along with the energy output from the accretion. After the black hole reaches a critical mass, outbursts powered by the continued consumption of gas prevent cooling and limit the production of new stars.
“It’s possible that the supermassive black hole reached a hefty size before there were many stars at all in the galaxy,” said Bogdan. “That is a significant change in our way of thinking about how galaxies and black holes evolve together.”
The results were presented June 11 at the 220th meeting of the American Astronomical Society in Anchorage, Alaska. The study also has been accepted for publication in The Astrophysical Journal.
A composite image of galaxy CID-4 shows evidence the black hole is being ejected. Credit: X-ray: NASA/CXC/SAO/F.Civano et al; Optical: NASA/STScI; Optical (wide field): CFHT, NASA/STScI
Talk about a tough neighborhood! Even black holes aren’t welcome in galaxy CID-42, located about 4 billion light-years away from Earth. Astronomers using the Chandra X-Ray Observatory have found strong evidence that a massive black hole is being ejected from this galaxy, moving out at a speed of several million kilometers per hour. This phenomenon, known as a recoiled black hole, happens due to a gravitational wave “kick” from the merger of two black holes.
Artist's impression of a binary system containing a stellar-mass black hole called IGR J17091-3624
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Astronomers using NASA’s Chandra X-ray Observatory have reported record-breaking wind speeds coming from a stellar-mass black hole.
The “wind”, a high-speed stream of material that’s being drawn off a star orbiting the black hole and ejected back out into space, has been clocked at a staggering 20 million miles per hour — 3% the speed of light! That’s ten times faster than any such wind ever measured from a black hole of its size!
The black hole, dubbed IGR J17091-3624 (IGR J17091 for short), is located about 28,000 light-years away in the constellation Scorpius. It is part of a binary system, with a Sun-like star in orbit around it.
“This is like the cosmic equivalent of winds from a category five hurricane,” said Ashley King from the University of Michigan, lead author of the study. “We weren’t expecting to see such powerful winds from a black hole like this.”
IGR J17091 exhibits wind speeds akin to black holes many times its mass… such winds have only ever been measured coming from black holes millions or even billions of times more massive.
“It’s a surprise this small black hole is able to muster the wind speeds we typically only see in the giant black holes,” said co-author Jon M. Miller, also from the University of Michigan.
Illustration of Cygnus X-1, another stellar-mass black hole located 6070 ly away. (NASA/CXC/M.Weiss)
Stellar-mass black holes are formed from the gravitational collapse of stars about 20 to 25 times the mass of our Sun.
“This black hole is performing well above its weight class,” Miller added.
IGR J17091 is also surprising in that it seems to be expelling much more material from its accretion disk than it is capturing. Up to 95% of the disk material is being blown out into space by the high-speed wind which, unlike polar jets associated with black holes, blows in many different directions.
While jets of material have been previously observed in IGR J17091, they have not been seen at the same time as the high-speed winds. This supports the idea that winds can suppress the formation of jets.
Chandra observations made two months ago did not show evidence of the winds, meaning they can apparently turn on and off. The winds are thought to be powered by constant variations in the powerful magnetic fields surrounding the black hole.
The study was published in the Feb. 20 issue of The Astrophysical Journal Letters.
Mysterious X-ray flares caught by Chandra may be asteroids falling into the Milky Way's giant black hole. Credit: X-ray: NASA/CXC/MIT/F. Baganoff et al.; Illustrations: NASA/CXC/M.Weiss
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For the past several years, the Chandra telescope has detected X-ray flares occurring about once a day from the supermassive black hole at the center of the Milky Way Galaxy. These flares last a few hours with brightness ranging from a few times to nearly one hundred times that of the black hole’s regular output. What could be causing these unusual, mysterious flares? Scientists have determined that the black hole could be feasting hungrily on asteroids that come too close and vaporizing them, creating the flares. Basically, the black hole is eating asteroids and then belching out X-ray gas.
If confirmed, this result would mean that there is a huge, bustling cloud around the black hole containing hundreds of trillions of asteroids and comets.
“People have had doubts about whether asteroids could form at all in the harsh environment near a supermassive black hole,” said Kastytis Zubovas of the University of Leicester in the United Kingdom, and lead author of a new paper. “It’s exciting because our study suggests that a huge number of them are needed to produce these flares.”
The scientists say this really isn’t as far-fetched as it may sound, as it mirrors an event that regularly takes place in our Solar System: About every three days a comet is destroyed when it flies into the hot atmosphere of the Sun. Despite the significant differences in the two environments, the destruction rate of comets and asteroids by the Sun and the black hole at the center of our galaxy, called Sagittarius A*, or “Sgr A*” for short, may be similar.
These asteroids and comets have likely been ripped from their parent stars, and to create the flare the asteroids or comets have to be fairly large, at least 19 km (12 miles) wide.
The astronomers propose this scenario: An asteroid undergoes a close encounter with another object, such as a star or planet, and is thrown into an orbit headed towards Sgr A*. If the asteroid passes within about 100 million miles of the black hole, roughly the distance between the Earth and the Sun, it would be torn into pieces by the tidal forces from the black hole. These fragments then would be vaporized by friction as they pass through the hot, thin gas flowing onto Sgr A*, similar to a meteor heating up and glowing as it falls through Earth’s atmosphere. A flare is produced and the remains of the asteroid are swallowed eventually by the black hole.
“An asteroid’s orbit can change if it ventures too close to a star or planet near Sgr A*,” said co-author Sergei Nayakshin, also of the University of Leicester. “If it’s thrown toward the black hole, it’s doomed.”
The team says these results reasonably agree with models estimating of how many asteroids are likely to be in this region, assuming that the number around stars near Earth is similar to the number surrounding stars near the center of the Milky Way.
“As a reality check, we worked out that a few trillion asteroids should have been removed by the black hole over the 10-billion-year lifetime of the galaxy,” said co-author Sera Markoff of the University of Amsterdam in the Netherlands. “Only a small fraction of the total would have been consumed, so the supply of asteroids would hardly be depleted.”
This scenario would not be limited to asteroids and comets, however. Planets thrown into orbits too close to Sgr A* also could also be disrupted by tidal forces, although planets in the region are less common. And of course, if a planet was consumed, it would create an even larger flare; and this may have occurred about a century ago when Sgr A* brightened by about a factor of a million. Chandra and other X-ray missions have seen evidence of an X-ray “light echo” reflecting off nearby clouds, providing a measure of the brightness and timing of the flare.
“This would be a sudden end to the planet’s life, a much more dramatic fate than the planets in our solar system ever will experience,” Zubovas said.
Very long observations of Sgr A* will be made with Chandra later in 2012 that will give valuable new information about the frequency and brightness of flares and should help to test the model proposed here to explain them. The team said this work could improve understanding about the formation of asteroids and planets in the harsh environment of Sgr A*.
Vital clues about the devastating ends to the lives of massive stars can be found by studying the aftermath of their explosions. In its more than twelve years of science operations, NASA's Chandra X-ray Observatory has studied many of these supernova remnants sprinkled across the Galaxy. Credit: X-ray: NASA/CXC/SAO/I.Lovchinsky et al, IR: NASA/JPL-Caltech
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Located some 14,700 light years from the Earth toward the center of our galaxy, a newly photographed supernova remnant cataloged as G350.1+0.3 is making astronomers scratch their heads. The star which created this unusual visage is suspected to have blown its top some 600 to 1,200 years ago. Although it would have been as bright as the event which created the “Crab”, chances are no one saw it due to the massive amounts of gas and dust at the Milky Way’s heart. Now NASA’s Chandra X-ray Observatory and the ESA’s XMM-Newton telescope has drawn back the curtain and we’re able to marvel at what happens when a supernova imparts a powerful X-ray “kick” to a neutron star!
Credit: X-ray: NASA/CXC/SAO/I.Lovchinsky et al, IR: NASA/JPL-CaltechPhotographic proof from Chandra and XMM-Newton are full of clues which give rise to the possibility that a compact object located in the influence of G350.1+0.3 may be the core region of a shattered star. Since it is off-centered from the X-ray emissions, it must have received a powerful blast of energy during the supernova event and has been moving along at a speed of 3 million miles per hour ever since. This information agrees with an “exceptionally high speed derived for the neutron star in Puppis A and provides new evidence that extremely powerful ‘kicks’ can be imparted to neutron stars from supernova explosions.”
As you look at the photo, you’ll notice one thing in particular… the irregular shape. The Chandra data in this image appears as gold while the infrared data from NASA’s Spitzer Space Telescope is colored light blue. According to the research team, this unusual configuration may have been caused by the stellar debris field imparting itself into the surrounding cold molecular gas.
These results appeared in the April 10, 2011 issue of The Astrophysical Journal. The scientists on this paper were Igor Lovchinsky and Patrick Slane (Harvard-Smithsonian Center for Astrophysics), Bryan Gaensler (University of Sydney, Australia), Jack Hughes (Rutgers University), Stephen Ng (McGill University), Jasmina Lazendic (Monash University Clayton, Australia), Joseph Gelfand (New York University, Abu Dhabi), and Crystal Brogan (National Radio Astronomy Observatory).
A pulsar within a supernova remnant in the Small Magellanic Cloud. X-rays are blue; optical data is red and green. (NASA/CXC/Univ.Potsdam/L.Oskinova et al.)
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For the first time astronomers have located a pulsar – the super-dense, spinning remains of a star – nestled within the remnants of a supernova in the Small Magellanic Cloud. The image above, a composite of x-ray and optical light data acquired by NASA’s Chandra Observatory and ESA’s XMM-Newton, shows the pulsar shining brightly on the right surrounded by the ejected outer layers of its former stellar life.
The optically-bright area on the left is a large star-forming region of dust and gas nearby SXP 1062.
A pulsar is a neutron star that emits high-energy beams of radiation from its magnetic poles. These poles are not always aligned with its axis of rotation, and so the beams swing through space as the neutron star spins. If the Earth happens to be in direct line with the beams at some point along their path, we see them as rapidly flashing radiation sources… sort of like a cosmic lighthouse on overdrive.
What’s unusual about this pulsar – called SXP 1062 – is its slow rate of rotation. Its beams spin around at a rate of about once every 18 minutes, which is downright poky for a pulsar, most of which spin several times a second.
X-ray image of SXP 1062
This makes SXP 1062 one of the slowest known pulsars discovered within the Small Magellanic Cloud, a dwarf galaxy cruising alongside our own Milky Way about 200,000 light-years distant.
The supernova that presumably created the pulsar and its surrounding remnant wrapping is estimated to have taken place between 10,000 and 40,000 years ago – relatively recently, by cosmic standards. To see a young pulsar spinning so slowly is extra unusual since younger pulsars have typically been observed to have rapid rotation rates. Understanding the cause of its leisurely pace will be the next goal for SXP 1062 researchers.
This unique photo mosaic utilizes a selection of images arranged in a pattern to resemble the Chandra spacecraft. (Credit: NASA/CXC/M.Weiss)
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Here’s a nifty mosaic from the folks at Chandra: a representation of the Chandra spacecraft made from images taken by the spacecraft itself. It was put together by Chandra illustrator Melissa Weiss. You can download larger and really huge versions of this image at the Chandra website.
