Astronomers believe they’ve found something never before detected in the universe: a black hole of intermediate size. And while that may not sound thrilling to the layman, researchers are thrilled by the discovery of the so-called “Hyper-Luminous X-ray Source 1,” which is poised at the edge of galaxy ESO 243-49. Astronomers are excited because they’ve seen plenty of small black holes and large black holes, but experts had questioned whether a medium-sized variety could exist. These middleweights, at about 500 times the mass of the sun, could represent a missing link between common stellar black holes, created by the death of a single star, and the supermassive variety that can pack the mass of millions or even billions of suns [SPACE.com].
Astronomers explain that small black holes, between three and 20 times the mass of the sun, are created when big stars collapse and leave behind a gravitational pull strong enough to block nearby light rays. Researchers have speculated that super-massive black holes result from the successive fusion of many smaller black holes. But without finding evidence of a medium-size hole, it was a tough theory to prove [Wired.com]. Supermassive black holes are of particular interest because they lurk at the hearts of most galaxies, and may play an important role in galaxy formation.
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In several labs around the world, sound waves are doing things they’ve never done before. Teams working in England and the Ukraine have made a sonic laser, or “saser,” which operates in the terahertz range, with sound waves oscillating more than a trillion times per second. Meanwhile, in an Israeli lab, researchers say they’ve created the first ever sonic black hole that traps sound waves and won’t let them escape.
The saser uses packets of sonic vibrations called “phonons” much like a regular laser uses photons. Specifically, the acoustic laser device consists of a sonic beam traveling through a “superlattice” constructed of 50 sheets of material each only atoms thick that are alternately made of gallium arsenide and aluminium arsenide, two materials found in semiconductor [CNET]. The phonons bounce back and forth inside the lattice, which causes more phonons to be released and amplifies the overall signal. The result is the formation of an intense series of synchronised phonons inside the stack, which leaves the device as a narrow saser beam of high-frequency ultrasound [New Scientist].
At the moment the terahertz saser, described in a paper published in the journal Physical Review B, is mainly a neat trick, but it may find practical applications down the line, says lead researcher Tony Kent. “Fifty years ago many eminent scientists said that light amplification by the stimulated emission of radiation [lasers] was no more than a scientific curiosity,” says Kent, but lasers are now used for everything from digital storage and cancer treatment to weaponry [New Scientist]. Kent says the new saser technology could lead to breakthroughs in imaging for tiny, nanoscale objects.
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Researchers have recalculated the mass of a gigantic black hole at the core of the M87 galaxy, and found that it’s about two times as massive as previously estimated: The new study says that M87′s black hole weighs the same as 6.4 billion suns. Researchers say the findings may indicate that many black holes have been underestimated, and also say that the results from this “local” galaxy only 50 million light-years away may solve a mystery regarding the extremely distant black holes known as quasars.
Astronomers had previously estimated M87′s total mass, calculating how much of that mass came from both the galaxy’s stars and its central black hole. But previous models didn’t have the supercomputing power to estimate the mass contributed by the galaxy’s “dark halo.” The dark halo is a spherical region surrounding the galaxy that extends beyond its main visible structure. It contains “dark matter”, an as yet unidentified material that cannot be directly detected by telescopes but which astronomers know is there from its gravitational interaction with everything else that can be seen [BBC News].
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When the universe was young, it somehow produced a giant space blob that has astronomers completely puzzled. Researchers have caught sight of an enormous patch of hot hydrogen gas officially known as a Lyman-alpha blob, named for a particular wavelength of light released when an electron loses energy in a hydrogen atom. It spans some 55,000 light years, about half the width of the Milky Way, and it sits some 12.9 billion light years from Earth. That means we are seeing it as it was 12.9 billion years ago, when the universe was just 800 million years old [New Scientist].
The blob poses a cosmological conundrum because astronomers didn’t think such a big cloud could form so early in the history of the universe. Current models hold that between 200 million and one billion years after the Big Bang, the first colossal stars formed, emitting radiation that stripped light elements of their electrons and turned the Universe into a soup of charged particles. Only after this “re-ionisation epoch” did matter as we now know it really start to clump together [BBC News]. Astronomers thought that objects as big as the newly discovered blob would take a great deal of time to gradually grow from the mergers of smaller chunks of matter.
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After yesterday’s alarming news that world-renowned physicist Stephen Hawking had been hospitalized and was “very ill” with a respiratory infection, reports from the hospital today come as a relief. According to Cambridge University, Hawking is now on the road to recovery. “He is comfortable and his family is looking forward to him making a full recovery,” the university, where Hawking is a professor of mathematics, said in a short statement [CNN].
Hawking’s ex-wife, Jane Hawking, also reassured the public. “I have been to see him and he’s fine – he’s doing well. I don’t think his condition is life-threatening” [Telegraph], she said. Others expressed their admiration for the man who hasn’t let his paralysis from Lou Gehrig’s disease slow him down. “He is amazingly resilient,” said Andrew Fabian, the head of the Royal Astronomical Society and a professor of astronomy at Cambridge. “He goes around the world — he does more traveling than most of us. … And he just seems unstoppable. It’s truly amazing” [AP].
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Stephen Hawking, the world-renowned physicist and author, is reportedly “very ill” and being treated at the hospital. Says University of Cambridge spokesman Greg Hayman: “Professor Hawking is very ill…. He has been suffering from a chest infection for a number of weeks which has meant he has had to cancel a number of appointments.” Hawking was flown back to the U.K. from the U.S. at the weekend, Hayman said. He was taken to hospital at lunch time today [Bloomberg].
Hawking has remained active despite being diagnosed at 21 with ALS, (amyotrophic lateral sclerosis), an incurable degenerative disorder also known as Lou Gehrig’s disease. For some years, Hawking has been almost entirely paralyzed, and he communicates through an electronic voice synthesizer activated by his fingers [AP].
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The sound of scientific discovery isn’t the clichéd “Eureka!” It’s much more like this recent exclamation from NASA astrophysicist Alan Kogut: “What the heck is this?” Dr. Kogut remembered exclaiming when he first saw the data. “This shouldn’t be here” [The New York Times].
Kogut was looking at a measurement of cosmic radio signals detected by sensitive antennas borne aloft in a balloon, which floated 21 miles above Texas for several hours. While scanning the sky, the instruments found a booming, uniformly distributed radio noise six times louder than anyone had predicted…. The researchers calculate that the radio noise is much too large to be accounted for by the combined emissions of all the galaxies in the universe that emit radio waves [Science News].
When researchers started to contemplate where that signal may have come from, things began to get interesting. It’s possible, says Kogut, that the radio waves may have been emitted during the death of the universe’s first stars. Those stellar pioneers were brutish monsters, so the story believed by most astronomers goes, lumbering clouds of hydrogen and helium hundreds of times more massive than the Sun. They lived fast and bright and died hard, exploding or collapsing into massive black holes less than a billion years after the Big Bang, never to be seen again [The New York Times]. When they collapsed into black holes, they may have spewed forth jets of charged particles that emitted these radio waves.
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Astronomers know that at the heart of every supermassive galaxy is a giant black hole. But new data suggests that the two did not necessarily form in tandem. Instead, black holes may have formed earlier, or at least much more quickly, than their surrounding galaxies. Previous studies had revealed a striking link between black holes and the amount of gas and stars contained in [their] galaxies’ bulges — the regions that lie within a few thousand light-years of the galaxies’ cores. Regardless of their size, the bulges always turned out to be 700 times as massive as the giant black holes at the galaxies’ hubs [Science News]. New measurements of much more distant galaxies, which appear much younger, defy the expected mass ratio. In these younger pairings, the relative mass of the black holes is much greater, hinting that the black holes came first.
Researchers used the Very Large Array radio telescope in New Mexico and the Plateau de Bure Interferometer in France to measure the mass of four distant galaxies as they appeared less than two billions years after the Big Bang. From the motions of the molecular gas, which concentrates in the central part of the galaxies, the team calculated the total amount of mass in the bulges and compared that number to the mass of the central black holes [Science News]. The galactic bulges were only about 30 times more massive than their central black holes. At the American Astronomical Society‘s meeting, where the work was presented, astronomer Chris Carilli said, “The simplest conclusion is that the black holes come first and they somehow grow the galaxy around them” [Wired News].
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In the violent heart of our Milky Way galaxy lies a supermassive black hole with a mass equivalent to four million suns. But although the gravitational maw gobbles up anything that gets too close, it can also set up conditions that allow for the birth of new stars just a few light years away, according to a new study. Lead researcher Elizabeth Humphreys says the results, which uncovered what appear to be two young stars as close as seven light-years from the galactic center, were surprising, as that is “one of the last places … you would expect to find stars forming” [Scientific American].
Gas clouds that approach a black hole are usually ripped apart by the intense gravitational forces, but the new finding suggests that the molecular gas at the center of the Milky Way from which the stars form is denser than previously thought. The higher density gas makes it easier for the self-gravity of the condensing cloud to overcome the strong pull of the black hole and to collapse to form new stars [SPACE.com].
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In a galaxy far, far away—11.1 billion light-years away, to be exact—researchers have discovered the telltale signature of water. The water molecules seem to be located in the galaxy’s center, where a supermassive black hole called a quasar is spewing out tons of radiation as material falls into it. The water molecules lie in clouds of dust and gas that feed the black hole, and appear to be amplifying radio waves at a specific frequency, forming what’s called a maser, or the radio equivalent of a laser [Wired News].
The quasar, called MG J0414+0534, is so far away that the light researchers are observing originated when the universe was only 2.5 billion years old. “We now know water is out there,” says Violette Impellizzeri from the Max Planck Institute (MPI) for Radio Astronomy in Bonn, Germany. “Because water masers arise close to the cores of galaxies, our result opens new interesting possibilities for studying supermassive black holes [at the galactic cores] at a time when galaxies were forming” [New Scientist].
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Astronomers have determined beyond all reasonable doubt that the heart of the Milky Way is a supermassive black hole, two research teams say. Astronomers have inferred the existence of a gravitational monster in the center of our galaxy for years, but the new results are “the best empirical evidence that super-massive black holes do really exist” [CNN], said researcher Reinhard Genzel.
Similar supermassive black holes are thought to form the center of many spiral and elliptical galaxies, and astronomer Robert Massey says the results suggest that galaxies form around giant black holes in the way that a pearl forms around grit. Dr Massey said: “Although we think of black holes as somehow threatening, in the sense that if you get too close to one you are in trouble, they may have had a role in helping galaxies to form – not just our own, but all galaxies” [BBC News]. Massey explains that if a black holes brings enough matter together in a dense cluster, it creates ripe conditions for the formations of stars and galaxies.
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A massive burst of gamma rays from a star that exploded billions of years ago reached Earth on March 19, and clocked in as the brightest burst of gamma rays ever observed, astronomers say. The blast, dubbed GRB 080319B, came from 7.5 billion light years away, more than halfway across the universe. Despite the immense distance, it would have been visible with the naked eye at dark sites on Earth for 40 seconds [New Scientist]. Researchers say they burst was so bright because the jet of matter and energy was pointed directly at Earth.
Gamma ray bursts, the universe’s most luminous explosions, occur when massive stars, perhaps 20 to 30 times the mass of the sun, burn out their nuclear fuel. As a star’s core collapses, it creates a black hole that drives powerful gas jets outward [Reuters]. The collisions of particles within those jets create high-energy gamma rays, which heat up surrounding gas and produce visible light. Nobody knows whether anyone looked up at the right spot in the sky at the right moment on March 19 to see the pulse of light, but NASA’s robotic Swift observatory did what it’s supposed to when it detects a gamma-ray burst, and swung into action [Ars Technica].
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Researchers have gotten the closest look yet at the supermassive black hole that is believed to lurk in the center of the Milky Way, using radio telescopes to peer through the cosmic dust. Lead astronomer Sheperd Doeleman says: “One of the problems with looking at this particular source is that we have to look through our galaxy. It’s a blessing that it’s this close, but it’s a curse because it’s obscured by gas and dust” [SPACE.com].
Black holes can’t be directly observed, because their gravitational pull is so strong that nothing, not even visible light, can escape. To study our local gravitational monster, researchers homed in on Sagittarius A*, the bright radio-emitting body thought to mark the position of the black hole. Because Sagittarius A* is likely fueled by the black hole’s activity, a better look at the radio-emitting body can provide more details about the black hole [Science News].
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Yesterday, NASA released the first set of images from its newest space telescope, the Gamma-Ray Large Area Space Telescope, which has now been renamed Fermi in honor of the particle physicist Enrico Fermi. After less than three months of collecting data, the Fermi telescope produced a map of the sky showing the sources of powerful gamma rays as bright spots of light.
“I like to call it our extreme machine,” said Jon Morse, the director of astrophysics for NASA. “It will help us crack the mysteries of these enormously powerful emissions.” Gamma rays are powerful light rays invisible to the naked eye [Washington Post]. As the Earth’s atmosphere absorbs gamma rays, they can only be studied from an orbiting telescope.
The $700 million telescope will observe gamma rays emitted by black holes, neutron stars, and other cosmic eccentrics, and will also scan the skies for the mysterious gamma ray bursts that are of special interest to astronomers because they are among the brightest events ever observed. The intense flashes of gamma rays can release within seconds the same amount of energy that the sun will put out over its entire ten-billion-year lifetime—but no one is sure what causes them. The going theory is that the bursts are tied to the explosive deaths of massive stars, but exactly what types of stars and how the explosions are triggered remains a mystery [National Geographic News]. Already, the Fermi telescope has detected gamma ray bursts at a rate of about one a day.
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In the heart of the Perseus galaxy cluster lies a remarkable galaxy known as NGC 1275, which has long “filaments”of glowing gas that snake out from its center. Astronomers have tried to explain how these beautiful structures can have survived for so long, given that the filaments reach out from their home galaxy into the Perseus cluster, which is a hostile, high-energy environment with a strong, tidal pull of gravity.These combined forces should have ripped apart the filaments in a very short time, causing them to collapse into stars [The Independent].
Now, thanks to images from the Hubble Space Telescope, astronomers say they understand how the filaments have held their shape for over 100 million years: Magnetic fields are keeping the filaments together, they say. The magnetic fields … hold onto the filaments because they wield influence over charged particles – such as protons and electrons – in the filaments’ gas [New Scientist].
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