Chaos Plagued the Early Universe

A new theory proposes that the earliest Universe, which formed immediately after the Big Bang, expanded in the space around it in an extremely chaotic manner.

This is not by far a new idea. It was proposed for the first time more than seven years ago, by Adilson E. Motter, who is a physics expert at the Northwestern University.

At the time when the idea was first conjectured, the physicist did not have the tools needed to prove it.

Now, with the help of a colleague, Motter finally managed to present the world with the mathematical utensils needed to demonstrate the theory rigorously.

Details of the work appear in a paper entitled “(Non)Invariance of Dynamical Quantities for Orbit Equivalent Flows,” which is published in the latest issue of the top-rated Journal Communications in Mathematical Physics.

The mathematical tools work extremely well when applied to the most widely-accepted model of how the Universe came to be.

The main conundrum the physicist was trying to crack is whether chaos is absolute or relative inside systems that are in themselves governed by general relativity.

In these systems, time itself is relative. For the purpose of the work, chaos was determined at the phenomenon by which tiny events lead to very large changes in the time evolution of a system.

The Universe therefore becomes a prime example of a chaotic system. An absolute thing, for example, is the speed of light, which remains the same regardless of where an observer is placed in time and space.

“A competing interpretation has been that chaos could be a property of the observer rather than a property of the system being observed,” says Motter, who is an assistant professor of physics and astronomy at the Northwestern Weinberg College of Arts and Sciences.

“Our study shows that different physical observers will necessarily agree on the chaotic nature of the system,” adds the expert, who is also the author of the new journal entry.

“Technically, we have established the conditions under which the indicators of chaos are relativistic invariants. Our mathematical characterization also explains existing controversial result,” Motter goes on to say.

“They were generated by singularities induced by the choice of the time coordinate, which are not present for physically admissible observables,” he concludes.

NASA To Probe First Moments Of The Universe

This graphic shows the universe as it evolved from the big bang to now. Goddard scientists believe that the universe expanded from subatomic scales to the astronomical in a fraction of a second after its birth. They now building, along with their university partner, an instrument that searches for clues that the inflation did, in fact, occur. Credit: NASA/WMAP Science Team

Sophisticated new technologies created by NASA and university scientists are enabling them to build an instrument designed to probe the first moments of the universe's existence.

Former NASA scientist Chuck Bennett, now an astrophysicist at Johns Hopkins University (JHU) in Baltimore, Md., won a $5-million National Science Foundation grant to build a new ground-based instrument, the Cosmology Large Angular Scale Surveyor (CLASS). Bennett is building CLASS with his collaborators at the NASA Goddard Space Flight Center in Greenbelt, Md.

Goddard will provide most of the instrument's sophisticated detectors and other state-of-the-art technologies that will allow the scientists to test the "inflation theory" of the universe's origin.

Staggering Idea
Considered a staggering idea just 30 years ago, the inflation theory postulates that the universe expanded far faster than the speed of light and grew exponentially almost instantaneously after the big bang, the moment the universe sprang into existence 13.7 billion years ago.

In particular, the telescope will search for a unique polarization pattern in the cosmic background radiation - the remnant light from the first moment of the universe's creation that bathes the sky in all directions. Because of the size and expansion of the universe, scientists can study this ancient light only if their instruments are tuned to microwave frequencies.

If the cosmic growth spurt from inflation really happened, scientists say the event could have created gravitational waves, which are ripples in the fabric of space. The theory also predicts that these gravitational waves would have caused the background light to be polarized in a particular pattern. The telescope, therefore, will look for this signature pattern.

"Miraculously enough, it is within our ability to probe back into the first moments of the universe and learn what happened then," Bennett said.

The CLASS team, which also includes other partner institutions, will complete the instrument in 2014, equipping it with detectors sensitive to microwave light. The team then will ship the instrument to the Atacama Desert in northern Chile where it will observe large swaths of the microwave sky in search of the polarized signature.

Tantalizing Clues
Although scientists have yet to find the polarization pattern, they have uncovered tantalizing clues that inflation did, in fact, happen. Scientific results from the Goddard-developed Cosmic Background Explorer (COBE) found tiny temperature differences in the cosmic background radiation. These differences varied by only a few millionths of a degree and pointed to density differences that eventually gave rise to the stars and galaxies seen today.

COBE's successor, the Goddard-led Wilkinson Microwave Anisotropy Probe (WMAP), examined the tiny temperature differences in more detail and discovered new evidence for inflation. Among other things, WMAP showed that the geometry of the universe is close to flat - a physical dimension attributable to inflation. However, other theories explain these dynamics. What the scientific community needs is definitive proof of the primordial gravity waves - phenomena that could have been produced only by inflation.

Another Goddard Mission Complements CLASS
CLASS is not the only effort aimed at finding the same telltale evidence. Another Goddard team is now building a balloon-based instrument, the Primordial Inflation Polarization Exploration (PIPER) that Principal Investigator Al Kogut hopes to launch in 2012. "CLASS and PIPER are perfect partners," said Goddard scientist Ed Wollack, who is involved in the CLASS project. "They share many technologies while spanning a wide frequency range. They will do great science while demonstrating the technologies for a space mission."

Although both CLASS and PIPER are looking for the same polarization signature, they will approach the challenge using different detector technologies to study different microwave frequencies. Both detector technologies were developed at Goddard.

"The more frequencies you study, the better your chance of detecting the pattern of inflation," said David Chuss, a Goddard scientist working on CLASS.

The ultimate goal for the Goddard-JHU team is leveraging its expertise with CLASS and PIPER and winning a possible follow-on space observatory that would examine the primordial background light with even greater precision. "What we're doing is very much what we need to do to be competitive for an observatory if NASA decides to launch one," Chuss said.

Our Universe At Home Within A Larger Universe

Einstein-Rosen bridges like the one visualized above have never been observed in nature, but they provide theoretical physicists and cosmologists with solutions in general relativity by combining models of black holes and white holes.

Could our universe be located within the interior of a wormhole which itself is part of a black hole that lies within a much larger universe? Such a scenario in which the universe is born from inside a wormhole (also called an Einstein-Rosen Bridge) is suggested in a paper from Indiana University theoretical physicist Nikodem Poplawski in Physics Letters B. The final version of the paper was available online March 29 and will be published in the journal edition April 12.

Poplawski takes advantage of the Euclidean-based coordinate system called isotropic coordinates to describe the gravitational field of a black hole and to model the radial geodesic motion of a massive particle into a black hole.

In studying the radial motion through the event horizon (a black hole's boundary) of two different types of black holes - Schwarzschild and Einstein-Rosen, both of which are mathematically legitimate solutions of general relativity - Poplawski admits that only experiment or observation can reveal the motion of a particle falling into an actual black hole.

But he also notes that since observers can only see the outside of the black hole, the interior cannot be observed unless an observer enters or resides within.

"This condition would be satisfied if our universe were the interior of a black hole existing in a bigger universe," he said.

"Because Einstein's general theory of relativity does not choose a time orientation, if a black hole can form from the gravitational collapse of matter through an event horizon in the future then the reverse process is also possible. Such a process would describe an exploding white hole: matter emerging from an event horizon in the past, like the expanding universe."

A white hole is connected to a black hole by an Einstein-Rosen bridge (wormhole) and is hypothetically the time reversal of a black hole. Poplawski's paper suggests that all astrophysical black holes, not just Schwarzschild and Einstein-Rosen black holes, may have Einstein-Rosen bridges, each with a new universe inside that formed simultaneously with the black hole.

"From that it follows that our universe could have itself formed from inside a black hole existing inside another universe," he said.

By continuing to study the gravitational collapse of a sphere of dust in isotropic coordinates, and by applying the current research to other types of black holes, views where the universe is born from the interior of an Einstein-Rosen black hole could avoid problems seen by scientists with the Big Bang theory and the black hole information loss problem which claims all information about matter is lost as it goes over the event horizon (in turn defying the laws of quantum physics).

This model in isotropic coordinates of the universe as a black hole could explain the origin of cosmic inflation, Poplawski theorizes.

Centaurus A Emits in Both Radio and Gamma-ray Wavelengths

In orbit only since June 2008, the Fermi Gamma-ray Space Telescope has already produced some remarkable science. One of the most remarkable findings it made so far was the fact that the closest active galaxy to the Milky Way, called Centaurus A, is capable of emitting both gamma-rays and radio radiation. In previous studies, it was proposed that a galaxy could either emit one or the other, but the new data seems to indicate that both types of emissions are possible at the same time.

An active galaxy is a space structure whose central region emits radiation across a very wide portion of the electromagnetic spectrum. Generally, the core is occupied by a supermassive black hole, which gobbles up matter, and then releases vast amounts of radiation in exchange. In the case of Centaurus A, which has for a long time been determined to be one of the most potent and bright sources of radio wavelengths in the sky, the core produced vast amounts of extremely high-energy gamma-rays as well, Space reports.

“This is something we've never seen before in gamma-rays,” explains of the new Fermi findings expert Teddy Cheung. He is a member of the team managing the observatory, and is based in Washington DC, at the Naval Research Laboratory (NRL). As far as physicists go, gamma-rays represent the most energetic form of light possible in the Universe. But, inside Centaurus A, these photons are ramped up to even higher energies than usual. The huge lobes of the active galaxy contain super-strong magnetic fields, in which a wide variety of particles get accelerated. The gamma-rays entering these highly-active regions also get a massive energy boost.

This results in what can perhaps be best described as the most energetic photons in the known Universe. Astrophysicists suspect that the situation is not unique and say that many of the active, massive galaxies out there may be producing the same amplification effect on their own gamma-ray sources. “Not only do we see the extended radio lobes, but their gamma-ray output is more than 10 times greater than their radio output,” Cheung adds. More details of the study appear in the April 2 issue of the esteemed publication Science.

How Dark Matter Behaves Around Black Holes

The standard explanation of how our Universe is set up states that roughly one quarter (23 percent) of everything is made out of dark matter, a form of matter that cannot be readily observed through conventional means. In fact, it has never been observed at all, although scientists tried out a wide variety of methods for detecting it. But now, two experts advance a new role for dark matter that proposes the stuff altered the amounts of galaxies in the Universe, and that it did so to a significant margin, AlphaGalileo reports.

Astronomers Dr Xavier Hernandez and Dr William Lee, both of whom are based at the National Autonomous University of Mexico (UNAM), say that their study was prompted by their curiosity in learning how dark matter would interact with the supermassive black holes that form at the cores of impressively-large galaxies. The team says that its models provided them with a new basis for calculating both these interactions and the rate at which dark matter would get sucked in through the event horizon.

The group determined the existence of a threshold in these rates. If the immediate surroundings of the black hole are laden with dark matter in amounts higher than 7 Sun masses per cubic light-year, then the initial black hole was found to be capable of growing at extremely fast rates. Their investigation also revealed that, if such a growth spur was activated, then the black hole would be fueled even further by dark matter, eventually consuming the galaxy around it. If the galaxy would survive this ordeal, the group says, then it would be altered beyond any possible recognition when compared to its original shape.

“Over the billions of years since galaxies formed, such runaway absorption of dark matter in black holes would have altered the population of galaxies away from what we actually observe,” Hernandez says. The greatest implication of their analysis is the fact that the amounts of dark matter present at the cores of galaxies needs must tend for a constant value, if the entire structure is to remain stable. An additional implication is that dark matter may be behaving in ways previously not thought-of. This means that current models aimed at explaining its behavior – and which therefore underline efforts to find the stuff – may have to be thought over.

Astronomers Get Sharpest View Ever of Star Factories in Distant Universe

Arp 220 is a nearby example of a merged starburst galaxy similar to SMM J2135-0102. Located 250 million light-years from Earth, Arp 220 is the aftermath of a collision between two spiral galaxies. The collision, which began about 700 million years ago, has sparked a crackling burst of star formation, resulting in about 200 huge star clusters in a packed, dusty region about 5,000 light-years across (about 5 percent of the Milky Way's diameter). The star clusters are the bluish-white bright knots visible in the Hubble image.

Credit: NASA, ESA, the Hubble Heritage-ESA/Hubble Collaboration, and A. Evans (UVa/NRAO/Stony Brook)

The distant galaxy SMM J2135-0102, shown here in 870-micron observations by the Submillimeter Array, has been gravitationally lensed by a foreground galaxy cluster. The galaxy's light is magnified and bent by gravity to produce mirror images of each of four star-forming regions (labeled A through D). If the galaxy were seen undistorted, it would appear like the inset at upper left. Regions A and D are separated by less than 6,000 light-years. The inset at lower right shows the resolution of the SMA image.

Credit: Mark Swinbank (Durham) and Steve Longmore (SAO)

Astronomers have combined a natural gravitational lens and a sophisticated telescope array to get the sharpest view ever of "star factories" in a galaxy over 10 billion light-years from Earth. They found that the distant galaxy, known as SMM J2135-0102, is making new stars 250 times faster than our Galaxy, the Milky Way. They also pinpointed four discrete star-forming regions within the galaxy, each over 100 times brighter than locations (like the Orion Nebula) where stars form in our Galaxy. This is the first time that astronomers have been able to study properties of individual star-forming regions within a galaxy so far from Earth.

"To a layperson, our images appear fuzzy, but to us, they show the exquisite detail of a Faberge egg," said Steven Longmore of the Harvard-Smithsonian Center for Astrophysics (CfA). Longmore is an author of the paper describing these findings, which was published in the March 21st Nature online.

Due to the time it takes light to travel to us, we see the galaxy as it existed just 3 billion years after the Big Bang. It was Milky Way-sized at the time. If we could see it today, 10 billion years later, it would have grown into a giant elliptical galaxy much more massive than our own.

"This galaxy is like a teenager going through a growth spurt," said Mark Swinbank of Durham University, lead author on the paper. "If you could see it today as an 'adult,' you'd find the galactic equivalent of Yao Ming the basketball player."

Sharpest View

From our point of view, SMM J2135-0102 is located behind a massive cluster of nearby galaxies. The cluster's gravity acts as a lens to magnify the more distant galaxy by a factor of 16 in both apparent size and brightness, bringing otherwise imperceptible details to light.

The galaxy, while heavily obscured by dust at visible wavelengths, emits prodigious amounts of light at submillimeter wavelengths (close to the radio region of the spectrum). Indeed, it is the brightest known submillimeter galaxy, making it a natural target for the Submillimeter Array (SMA).

The SMA is an 8-element interferometer operating in the wavelength range of 0.3 to 2 millimeters, located atop Mauna Kea in Hawaii. Combined with the natural magnification of the gravitational lens, the array provided extremely high resolution observations - equivalent to using a telescope in Boston to spot a dime in Washington DC. This yielded a level of detail for a galaxy 10 billion light-years away comparable to the best observations of nearby starburst galaxies (which also show high rates of star formation).

Because of the obscuring dust, the galaxy's distance could not be determined by observations of visible light. For that task, the astronomers turned to a unique instrument, called the "Zpectrometer," on the National Science Foundation's Robert C. Byrd Green Bank Telescope. This instrument was able to determine the galaxy's distance by measuring radio emission from carbon monoxide molecules. The precise distance measurement allowed the scientists to determine "the exact effect that gravitational lensing would have on the galaxy, and therefore exactly how the galaxy would look in the absence of lensing," according to Andrew Baker, of Rutgers University.

Star Factories

The SMA data revealed four extremely bright star-forming regions. The large luminosities, 100 times greater than typical for nearby galaxies, imply a very high rate of star formation.

"We don't fully understand why the stars are forming so rapidly, but our result suggests that stars formed much more efficiently in the early universe than they do today," said Swinbank.

Their results provide new insight into a critical time during the Universe's history. SMM J2135-0102 is seen at the epoch when the majority of all stars were born, and therefore when many of the properties of nearby galaxies were defined. By studying it and other distant galaxies in the young Universe, astronomers hope to learn about the history of the Milky Way and other nearby galaxies.

Future surveys should identify more targets for study by the SMA and next-generation telescopes such as the Atacama Large Millimeter Array.

"That will allow us to test exactly how generic our results are: Is the star formation occurring within galaxies in the early Universe always so vigorous? Or are we catching this particular galaxy at a very special time?" said Longmore.

Source: Harvard-Smithsonian Center for Astrophysics

New Hubble treasury project to survey first third of cosmic time

The images above of galaxies in the Hubble Ultra Deep Field show the power of the new WFC3 camera (top row) versus the older ACS camera (bottom row, longer exposures). The historic HUDF image below, released in 2004, combines data from the ACS and NICMOS cameras. Image credits: NASA, ESA, S. Beckwith (STScI), and HUDF Team.

Astronomers will peer deep into the universe in five directions to document the early history of star formation and galaxy evolution in an ambitious new project requiring an unprecedented amount of time on the Hubble Space Telescope.

By imaging more than 250,000 distant galaxies, the project will provide the first comprehensive view of the structure and assembly of galaxies over the first third of cosmic time. It will also yield crucial data on the earliest stages in the formation of supermassive black holes and find distant supernovae important for understanding dark energy and the accelerating expansion of the universe.

Project leader Sandra Faber of the University of California, Santa Cruz, said the effort relies on Hubble's powerful new infrared camera, the Wide Field Camera 3 (WFC3), as well as the telescope's Advanced Camera for Surveys (ACS). The proposal, which brings together a large international team of collaborators, was awarded a record 902 orbits of observing time as one of three large-scale projects chosen for the Hubble Multi-Cycle Treasury Program. The observing time, totaling about three and a half months, will be spread out over the next two to three years.

"This is an effort to make the best use of Hubble while it is at the apex of its capabilities, providing major legacy data sets for the ages," said Faber, a University Professor and chair of astronomy and astrophysics at UCSC.

The committee that reviewed proposals for the Hubble Multi-Cycle Treasury Program asked Faber to combine her initial proposal with a similar one led by Henry Ferguson, an astronomer at the Space Telescope Science Institute (STScI), which operates the Hubble telescope. Faber and Ferguson will work together to manage the project, which involves more than 100 investigators from dozens of institutions around the world.

A powerful telescope like Hubble allows astronomers to see back in time as it gathers light that has traveled for billions of years across the universe. The new survey is designed to observe galaxies at distances that correspond to "look-back times" from nearly 13 billion years ago (about 600,000 years after the Big Bang) up to about 9 billion years ago. Astronomers express these distances in terms of redshift ("z"), a measure of how the expansion of the universe shifts the light from an object to longer wavelengths. The redshift increases with distance, and this study will look at objects at distances from about z=1.5 to z=8.

"We want to look very deep, very far back in time, and see what galaxies and black holes were doing back then," Faber said. "It's important to observe in different regions, because the universe is very clumpy, and to have a large enough sample to count things, so we can see how many of one kind of object versus another kind there were at different times."

One of Faber's colleagues at UCSC, Garth Illingworth, recently demonstrated the power of Hubble's new camera when his team described the most distant galaxies ever detected (see earlier story). Illingworth's team focused on one small patch of sky known as the Hubble Ultra Deep Field. Faber's team will look both "deep" and "wide" to collect observations of a large number of distant objects in different regions of the sky.

The new data will be used to answer many key questions about galaxy evolution and cosmology. By studying how galaxy masses, morphologies, and star formation rates changed over time, researchers can test theories of galaxy formation and evolution.

"The earliest galaxies we see are truly infant galaxies. We want to know when massive galaxies first appeared, and when they started to look like the beautiful spiral galaxies we see today," Faber said. "This study will allow us to chart for the first time the maturation process of galaxies."

Of all the stars that have formed in the universe, only about 1 percent had formed by the time of the most distant epoch included in the survey. "When you combine our data with closer Hubble surveys, the telescope now covers 99 percent of all star formation in the universe," Faber said. "All but the very first moments of galaxy evolution will be revealed."

The study focuses on several patches of sky where deep observations with other instruments are providing data in multiple wavelengths of light, including x-ray data from NASA's Chandra X-ray Observatory. X-ray emissions reveal the presence of a supermassive black hole at the core of a galaxy powering an "active galactic nucleus." Understanding the role of black holes in the evolution of galaxies is an important aspect of this project, Faber said.

"We don't know if the black holes form later or are a central feature of these galaxies from the very beginning. We hope to observe the earliest stages of black hole growth," she said.

Another important component of the project is the search for distant examples of a particular type of exploding star known as a Type Ia supernova. Astronomers have used the uniform brightness of these supernovae to measure cosmic distances, leading to the conclusion that a mysterious force called dark energy is accelerating the expansion of the universe. Observations of distant Type Ia supernovae will enable researchers to verify that their brightnesses are indeed uniform and to measure more accurately how the rate of expansion of the universe has changed over time.

Faber and her fellow astronomers expect the first data from their observations to be available by the end of the year. Data from this project will be made available to the entire astronomy community with no proprietary period for Faber's team to conduct their own analysis. The likely result will be a race among teams of scientists to publish the first results from this new treasure trove of data. But Faber said the project will yield such rich data it will keep astronomers busy for years to come.

"We're very excited, not only about the 900 orbits, but also about what this new camera can do. It's just amazing what it sees," Faber said. "This project is the biggest event in my career, the culmination of three decades of work using big telescopes to study galaxy evolution."

Additional information about the project is available on the Cosmology Survey Multi-Cycle Treasury Program web site.

A View of the Coldest Place in the Universe

Image comment: This image shows that the Boomerang Nebula should more accurately be called the Bowtie Nebula

Image credits: NASA / ESA

Scientists at the European Southern Observatory (ESO) discovered in 1995 what was at the time believed to be the coldest object in the Universe. Using the Chile-based ESO Submillimeter Telescope, the experts looked deep in space, and identified the Boomerang Nebula, which featured temperatures as low as minus 272 degrees Celsius. This means that the entire stellar nursery is no more than 1 degree Celsius warmed than absolute zero, Space Fellowship reports.

This particular structure is not your average star-forming nebula. Usually the term applies to stellar nurseries, massive clouds of hydrogen gas and new stars. Inside, constant stirring by stellar winds and interacting gravitational forces collapse large gas clouds into freshly-formed blue stars, which go on to repeat the cycle of their predecessors. But the Boomerang is a planetary nebula, which is basically an emission nebula that features an expanding glowing shell of ionized gas and plasma. Its name was derived from the first observations of such a structure, conducted in the 18th century. Through the small optical telescopes available at the time, these formations looked like giant planets.

In this new image of the Boomerang Nebula, we are treated to new details about the structure. This particular photo was snapped by the Hubble Space Telescope, and is another testament to the amazing resolve power the scientific instruments aboard the famous observatory have. The Nebula itself is located some 5,000 light-years away, in the direction of the Centaurus Constellation. What is tremendously interesting about it is that it's even colder than the cosmic microwave background (CMB), the afterglow left behind from the time when the Big Band exploded the Universe into being.

In this 1980 image, we see that the lobes of the nebula have yet to develop the bubble-like appearance that other similar structures have, which would appear to indicate that it is very young. In addition, a central star is also visible here, most likely in its dying throes. Stellar winds traveling at speeds in excess of 500,000 kilometers per hour are most likely responsible for the general shape of the Boomerang Nebula, researchers hypothesize. The star is believed to be losing mass for at least 1,500 years, and astrophysicists say that the equivalent of one thousandth of a solar mass is being emitted each year. This allows for the nebula to expand very rapidly, and become incredibly cool.

Mysterious cosmic 'dark flow' tracked deeper into universe

The colored dots are clusters within one of four distance ranges, with redder colors indicating greater distance. Colored ellipses show the direction of bulk motion for the clusters of the corresponding color. Images of representative galaxy clusters in each distance slice are also shown.

Distant galaxy clusters mysteriously stream at a million miles per hour along a path roughly centered on the southern constellations Centaurus and Hydra. A new study led by Alexander Kashlinsky at NASA's Goddard Space Flight Center in Greenbelt, Md., tracks this collective motion -- dubbed the "dark flow" -- to twice the distance originally reported. "This is not something we set out to find, but we cannot make it go away," Kashlinsky said. "Now we see that it persists to much greater distances -- as far as 2.5 billion light-years away." The new study appears in the March 20 issue of The Astrophysical Journal Letters.

The clusters appear to be moving along a line extending from our solar system toward Centaurus/Hydra, but the direction of this motion is less certain. Evidence indicates that the clusters are headed outward along this path, away from Earth, but the team cannot yet rule out the opposite flow. "We detect motion along this axis, but right now our data cannot state as strongly as we'd like whether the clusters are coming or going," Kashlinsky said.

The dark flow is controversial because the distribution of matter in the observed universe cannot account for it. Its existence suggests that some structure beyond the visible universe -- outside our "horizon" -- is pulling on matter in our vicinity.

Cosmologists regard the microwave background -- a flash of light emitted 380,000 years after the universe formed -- as the ultimate cosmic reference frame. Relative to it, all large-scale motion should show no preferred direction.

The hot X-ray-emitting gas within a galaxy cluster scatters photons from the cosmic microwave background (CMB). Because galaxy clusters don't precisely follow the expansion of space, the wavelengths of scattered photons change in a way that reflects each cluster's individual motion.

This results in a minute shift of the microwave background's temperature in the cluster's direction. The change, which astronomers call the kinematic Sunyaev-Zel'dovich (KSZ) effect, is so small that it has never been observed in a single galaxy cluster.

But in 2000, Kashlinsky, working with Fernando Atrio-Barandela at the University of Salamanca, Spain, demonstrated that it was possible to tease the subtle signal out of the measurement noise by studying large numbers of clusters.

In 2008, armed with a catalog of 700 clusters assembled by Harald Ebeling at the University of Hawaii and Dale Kocevski, now at the University of California, Santa Cruz, the researchers applied the technique to the three-year WMAP data release. That's when the mystery motion first came to light.

The new study builds on the previous one by using the five-year results from WMAP and by doubling the number of galaxy clusters.

"It takes, on average, about an hour of telescope time to measure the distance to each cluster we work with, not to mention the years required to find these systems in the first place," Ebeling said. "This is a project requiring considerable followthrough."

According to Atrio-Barandela, who has focused on understanding the possible errors in the team's analysis, the new study provides much stronger evidence that the dark flow is real. For example, the brightest clusters at X-ray wavelengths hold the greatest amount of hot gas to distort CMB photons. "When processed, these same clusters also display the strongest KSZ signature -- unlikely if the dark flow were merely a statistical fluke," he said.

In addition, the team, which now also includes Alastair Edge at the University of Durham, England, sorted the cluster catalog into four "slices" representing different distance ranges. They then examined the preferred flow direction for the clusters within each slice. While the size and exact position of this direction display some variation, the overall trends among the slices exhibit remarkable agreement.

The researchers are currently working to expand their cluster catalog in order to track the dark flow to about twice the current distance. Improved modeling of hot gas within the galaxy clusters will help refine the speed, axis, and direction of motion.

Future plans call for testing the findings against newer data released from the WMAP project and the European Space Agency's Planck mission, which is also currently mapping the microwave background.

Source: NASA/Goddard Space Flight Center

Vela Pulsar And Dozens Of Others Get Probed

Two studies published in Science Express show the analysis of gamma-rays from two dozen pulsars, including 16 discovered by NASA's Fermi Gamma-ray Space Telescope. Fermi is the first spacecraft able to identify pulsars by their gamma-ray emissions alone.

A pulsar is the rapidly spinning and highly magnetized core left behind when a massive star explodes. Most of the currently cataloged pulsars, some 1800 of them, were found through their periodic radio emissions; pulses caused by narrow, lighthouse-like radio beams emanating from the pulsar's magnetic poles, according to current theory.

The Vela pulsar, which spins 11 times a second, is the brightest persistent source of gamma rays in the sky. Yet gamma rays -- the most energetic form of light -- are few and far between. Even Fermi's Large Area Telescope sees only about one gamma-ray photon from Vela every two minutes.

"That's about one photon for every thousand Vela rotations," said Marcus Ziegler, a member of the team reporting on the new pulsars at the University of California, Santa Cruz. "From the faintest pulsar we studied, we see only two gamma-ray photons a day."

Radio telescopes on Earth can detect a pulsar easily only if one of the narrow radio beams happens to swing our way. If not, the pulsar can remain hidden.

A pulsar's radio beams represent only a few parts per million of its total power, whereas its gamma rays account for 10 percent or more. Somehow, pulsars are able to accelerate particles to speeds near that of light. These particles emit a broad beam of gamma rays as they arc along curved magnetic field lines.

The new pulsars were discovered as part of a comprehensive search for periodic gamma-ray fluctuations using five months of Fermi Large Area Telescope data and new computational techniques.

"Before launch, some predicted Fermi might uncover a handful of new pulsars during its mission," Ziegler added. "To discover 16 in its first five months of operation is really beyond our wildest dreams."

Like spinning tops, pulsars slow down as they lose energy. Eventually, they spin too slowly to power their characteristic emissions and become undetectable.

This all-sky map shows the positions and names of 16 new pulsars (yellow) and eight millisecond pulsars (magenta) studied using Fermi's LAT. The famous Vela, Crab, and Geminga pulsars (right) are the brightest ones Fermi sees. The pulsars Taz, Eel, and Rabbit have taken the nicknames of nebulae they are now known to power. The Gamma Cygni pulsar resides within a supernova remnant of the same name. Credit: NASA/DOE/Fermi LAT Collaboration

But pair a slowed dormant pulsar with a normal star, and a stream of stellar matter from the companion can spill onto the pulsar and increase its spin. At rotation periods between 100 and 1,000 times a second, ancient pulsars can resume the activity of their youth. In the second study, Fermi scientists examined gamma rays from eight of these "born-again" pulsars, all of which were previously discovered at radio wavelengths.

"Before Fermi launched, it wasn't clear that pulsars with millisecond periods could emit gamma rays at all," said Lucas Guillemot at the Center for Nuclear Studies in Gradignan, near Bordeaux, France. "Now we know they do. It's also clear that, despite their differences, both normal and millisecond pulsars share similar mechanisms for emitting gamma rays."

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the U.S.

A galaxy as particle accelerator

The giant radio galaxy Messier 87 is located in our immediate "cosmic vicinity", only about 55 million light years away. In the bright outflow of matter from the center of Messier 87, particles are accelerated to near the speed of light. Scientists were now able to show, combining observations from the lowest and highest end of the electromagnetic spectrum, that particle acceleration to the highest energies takes place very close the center of Messier 87.

This time series of radio difference images (with respect to the temporal average image) of the innermost part of M87 shows a substantial brightening of the innermost core region in spring 2008, which coincides with the period of increased very high energy gamma-ray emission.

It is one of the largest among the giants: With two to three billion times the mass of our sun, the galaxy Messier 87 dominates the Virgo cluster. A supermassive black hole exists in the centre of this galaxy. So called jets (gigantic plasma flows) shoot out from the vicinity of the black hole at close to light speed. Scientists - among others from the Max Planck Institutes for Nuclear Physics and Physics - have observed, simultaneously in gamma and radio frequencies, this active galactic core region. Thereby they discovered that the elementary particles are accelerated to extremely high energy levels in closest proximity to the black hole (Science Express, July 2, 2009). Messier 87 is a giant elliptical radio galaxy in our immediate cosmic vicinity, just 55 million light years away. In its centre, it hosts a super-massive black hole, about six thousand million times more massive than our own Sun. In a "jet", a giant outflow from the central engine of this galaxy, charged particles (electrons and protons) may be accelerated to velocities close to the speed of light. Inevitable witnesses and messengers of these acceleration processes are very-high-energy gamma rays, photons a thousand billion times more energetic than optical light. They are produced when the accelerated particles interact with their environment.

High-energy gamma rays constitute the highest energy electromagnetic radiation observable, and are generated by the most violent cosmic objects such as supernovae, active galactic nuclei, and gamma ray bursts. They allow us to study a realm of extreme physical conditions, far beyond what can be studied in laboratories here on Earth.

First indications for very-high energy gamma radiation from Messier 87 were found as early as 1998 with the HEGRA telescopes, which was the predecessor experiment of H.E.S.S. and MAGIC. This detection could be confirmed with the H.E.S.S. telescopes in 2006. These observations also revealed a fast variability of the gamma-ray flux within few days, as seen again in the 2008 campaign. This implies that the extension of the gamma-ray source must be exceptionally compact, and is located presumably in the immediate vicinity of the supermassive black hole in Messier 87.

In early 2008, the three world-leading instruments sensitive to gamma rays in this energy domain, H.E.S.S., MAGIC and VERITAS, jointly observed Messier 87 from January to May 2008, collecting 120 hours' worth of data. During this campaign, Messier 87 underwent two major outbursts of gamma-ray emission. Simultaneous high resolution radio observations of the activity of Messier 87 using the VLBA, a system of ratio telescopes spanning the United States, indicate a persistent increase of the radio flux from the innermost "core" of Messier 87, which is associated with the immediate vicinity of the central black hole. The collaboration of observatories sensitive to the lowest (radio) and highest (gamma-ray) parts of the electromagnetic spectrum made it possible for the first time to pin down the location of activity during the gamma-ray outbursts and thus the site of the particle accelerator in Messier 87.

Source: Max-Planck-Gesellschaft

University of Hawaii at Manoa astronomers discover pair of solar systems in the making

Left: This is a Submillimeter Array image of 253-1536 taken at a wavelength of 880 microns. The mass of the disk on the left is 70 times the mass of Jupiter, while the one on the right is 20 Jupiter masses. Right: The optical image taken by the Hubble Space Telescope shows the shadow of the large disk, but the smaller disk is obscured in the glare of the brighter star.

Two University of Hawai'i at Mānoa astronomers have found a binary star-disk system in which each star is surrounded by the kind of dust disk that is frequently the precursor of a planetary system. Doctoral student Rita Mann and Dr. Jonathan Williams used the Submillimeter Array on Mauna Kea, Hawaii to make the observations. A binary star system consists of two stars bound together by gravity that orbit a common center of gravity. Most stars form as binaries, and if both stars are hospitable to planet formation, it increases the likelihood that scientists will discover Earth-like planets.

This binary system, 253-1536, stands out as the first known example of two optically visible stars, each surrounded by a disk with enough mass to form a planetary system like our own. It lies 1,300 light-years from Earth, in the famous Orion Nebula, the kind of rich cluster of stars that is a common birth environment for most stars in our Milky Way galaxy, including our sun.

One of the disks was discovered in an image taken with the Hubble Space Telescope, but the other disk was hidden in the glare of the star. Hubble saw only the disk shadow, so the amount of material and its capability for planet formation was unknown until the UH team made the SMA observations. "The SMA was able to image the binary system at almost the same level of detail as the Hubble Space Telescope, but in the extreme infrared, where we can see the glow from the dust, rather than its shadow," explained Mann.

The two stars are 400 times farther from each other than Earth is from the sun. They would take 4,500 years, or about the length of human recorded history, to complete one orbit around their common center. Both stars are only about a third the mass of our sun and are much cooler and redder in color. Viewed from a potential future planet, the stellar neighbor would appear as an intense point in the night sky, about one thousand times brighter than the brightest star in our night sky, Sirius. Planets around the other star would be visible only through telescopes, but they would be within reach of spacecraft from a civilization with the same level of technology as ours.

The larger disk in 253-1536 is also the most massive found in the Orion Nebula so far. The discovery of this massive disk and the binary disk system improve our understanding of how common planet formation is in our Galaxy and place our Solar System in context.

Source: University of Hawaii at Manoa

Intense heat killed the Universe's would-be galaxies, researchers say

Our Milky Way galaxy only survived because it was already immersed in a large clump of dark matter which trapped gases inside it, scientists led by Durham University's Institute for Computational Cosmology (ICC) found. The research, to be presented at an international conference today (Wednesday, July 1), also forms a core part of a new ICC movie charting the evolution of the Milky Way to be shown at the Royal Society.

The researchers said that the early Milky Way, which had begun forming stars, held on to the raw gaseous material from which further stars would be made. This material would otherwise have been evaporated by the high temperatures generated by the "ignition" of the Universe about half-a-billion years after the Big Bang.

Tiny galaxies, inside small clumps of dark matter, were blasted away by the heat which reached approximate temperatures of between 20,000 and 100,000 degrees centigrade, the scientists, including experts at Japan's University of Tsukuba, said.

Dark matter is thought to make up 85 per cent of the Universe's mass and is believed to be one of the building blocks of galaxy formation.

Using computer simulations carried out by the international Virgo Consortium (which is led by Durham) the scientists examined why galaxies like the Milky Way have so few companion galaxies or satellites.

Astronomers have found a few dozen small satellites around the Milky Way, but the simulations revealed that hundreds of thousands of small clumps of dark matter should be orbiting our galaxy.

The scientists said the heat from the early stars and black holes rendered this dark matter barren and unable to support the development of satellite star systems.

The findings will be presented to The Unity of the Universe conference to be held at the Institute of Cosmology and Gravitation, at the University of Portsmouth on Wednesday, July 1. The work has been funded by the Science and Technology Facilities Council (STFC) and the Japanese Society for the Promotion of Science.

The simulations also form part of a new ICC movie – called Our Cosmic Origins – which combines ground-breaking simulations with observations of galaxies to track the evolution of the Milky Way over the 13-billion-year history of the Universe.

The movie is part of the ICC's exhibit at The Royal Society's annual Summer Science Exhibition which runs until this Saturday (July 4).

Joint lead investigator Professor Carlos Frenk, Director of the Institute for Computational Cosmology, at Durham University, said: "The validity of the standard model of our Universe hinges on finding a satisfactory explanation for why galaxies like the Milky Way have so few companions.

"The simulations show that hundreds of thousands of small dark matter clumps should be orbiting the Milky Way, but they didn't form galaxies.

"We can demonstrate that it was almost impossible for these potential galaxies to survive the extreme heat generated by the first stars and black holes.

"The heat evaporated gas from the small dark matter clumps, rendering them barren. Only a few dozen front-runners which had a head start on making stars before the Universe ignited managed to survive."

By providing a natural explanation for the origin of galaxies, the simulations support the view that cold dark matter is the best candidate for the mysterious material believed to make up the majority of our Universe, the scientists added.

It is now up to experimental physicists to either find this dark matter directly or to make it in a particle accelerator such as the Large Hadron Collider at CERN.

Professor Frenk, added: "Identifying the dark matter is not only one of the most pressing problems in science today, but also the key to understanding the formation of galaxies."

Joint lead investigator Dr Takashi Okamoto from the University of Tsukuba said: "These are still early days in trying to make realistic galaxies in a computer, but our results are very encouraging."

Source: Durham University

Astronomer's new guide to the galaxy: largest map of cold dust revealed

Colour-composite annotated image of part of the Galactic Plane seen by the ATLASGAL survey, divided into sections. In this image, the ATLASGAL submillimetre-wavelength data are shown in red, overlaid on a view of the region in infrared light, from the Midcourse Space Experiment (MSX) in green and blue. The total size of the image is approximately 42 degrees by 1.75 degrees.

Some of the most prominent features visible in the image are (from left to right, top to bottom):

• Messier 20 (the Trifid Nebula): A nebula containing an open cluster of stars as well as a stellar nursery. The name “Trifid” refers to the way that dense dust appears to divide it into three lobes at visible wavelengths.
• Sagittarius B2 (Sgr B2): One of the largest clouds of molecular gas in the Milky Way, this dense region lies close to the Galactic Centre and is rich in many different interstellar molecules.
• Galactic Centre: The centre of the Milky Way, home to a supermassive black hole more than four million times the mass of our Sun. It is about 25 000 light-years from Earth.
• NGC 6357: A diffuse nebula containing the open cluster Pismis 24, home to several very massive stars.
• NGC 6334: An emission nebula also known as the “Cat’s Paw Nebula”.
• RCW 120: A region where an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps that are the birthplaces of new stars.
• The Norma Arm: The region of somewhat brighter emission extending over about 10 degrees on the right-hand side of the image corresponds to the position of the Norma Arm, one of the spiral arms of the Milky Way.

This image in full-resolution (TIF format, 46 MB) is available on this link.

Astronomers have unveiled an unprecedented new atlas of the inner regions of the Milky Way, our home galaxy, peppered with thousands of previously undiscovered dense knots of cold cosmic dust — the potential birthplaces of new stars. Made using observations from the APEX telescope in Chile, this survey is the largest map of cold dust so far, and will prove an invaluable map for observations made with the forthcoming ALMA telescope, as well as the recently launched ESA Herschel space telescope.

This new guide for astronomers, known as the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) shows the Milky Way in submillimetre-wavelength light (between infrared light and radio waves [1]). Images of the cosmos at these wavelengths are vital for studying the birthplaces of new stars and the structure of the crowded galactic core.

“ATLASGAL gives us a new look at the Milky Way. Not only will it help us investigate how massive stars form, but it will also give us an overview of the larger-scale structure of our galaxy”, said Frederic Schuller from the Max Planck Institute for Radio Astronomy, leader of the ATLASGAL team.

The area of the new submillimetre map is approximately 95 square degrees, covering a very long and narrow strip along the galactic plane two degrees wide (four times the width of the full Moon) and over 40 degrees long. The 16 000 pixel-long map was made with the LABOCA submillimetre-wave camera on the ESO-operated APEX telescope. APEX is located at an altitude of 5100 m on the arid plateau of Chajnantor in the Chilean Andes — a site that allows optimal viewing in the submillimetre range. The Universe is relatively unexplored at submillimetre wavelengths, as extremely dry atmospheric conditions and advanced detector technology are required for such observations.

The interstellar medium — the material between the stars — is composed of gas and grains of cosmic dust, rather like fine sand or soot. However, the gas is mostly hydrogen and relatively difficult to detect, so astronomers often search for these dense regions by looking for the faint heat glow of the cosmic dust grains.

Submillimetre light allows astronomers to see these dust clouds shining, even though they obscure our view of the Universe at visible light wavelengths. Accordingly, the ATLASGAL map includes the denser central regions of our galaxy, in the direction of the constellation of Sagittarius — home to a supermassive black hole (ESO 46/08) — that are otherwise hidden behind a dark shroud of dust clouds.

The newly released map also reveals thousands of dense dust clumps, many never seen before, which mark the future birthplaces of massive stars. The clumps are typically a couple of light-years in size, and have masses of between ten and a few thousand times the mass of our Sun. In addition, ATLASGAL has captured images of beautiful filamentary structures and bubbles in the interstellar medium, blown by supernovae and the winds of bright stars.

Some striking highlights of the map include the centre of the Milky Way, the nearby massive and dense cloud of molecular gas called Sagittarius B2, and a bubble of expanding gas called RCW120, where the interstellar medium around the bubble is collapsing and forming new stars (see ESO 40/08).

“It’s exciting to get our first look at ATLASGAL, and we will be increasing the size of the map over the next year to cover all of the galactic plane visible from the APEX site on Chajnantor, as well as combining it with infrared observations to be made by the ESA Herschel Space Observatory. We look forward to new discoveries made with these maps, which will also serve as a guide for future observations with ALMA”, said Leonardo Testi from ESO, who is a member of the ATLASGAL team and the European Project Scientist for the ALMA project.

Note

[1] The map was constructed from individual APEX observations in radiation at 870 µm (0.87 mm) wavelength.

More information:

The ATLASGAL observations are presented in a paper by Frederic Schuller et al., ATLASGAL — The APEX Telescope Large Area Survey of the Galaxy at 870 µm, published in Astronomy & Astrophysics. ATLASGAL is a collaboration between the Max Planck Institute for Radio Astronomy, the Max Planck Institute for Astronomy, ESO, and the University of Chile.

LABOCA (Large APEX Bolometer Camera), one of APEX’s major instruments, is the world’s largest bolometer camera (a "thermometer camera", or thermal camera that measures and maps the tiny changes in temperature that occur when sub-millimetre wavelength light falls on its absorbing surface; see ESO 35/07). LABOCA’s large field of view and high sensitivity make it an invaluable tool for imaging the “cold Universe”. LABOCA was built by the Max Planck Institute for Radio Astronomy.

The Atacama Pathfinder Experiment (APEX) telescope is a 12-metre telescope, located at 5100 m altitude on the arid plateau of Chajnantor in the Chilean Andes. APEX operates at millimetre and submillimetre wavelengths. This wavelength range is a relatively unexplored frontier in astronomy, requiring advanced detectors and an extremely high and dry observatory site, such as Chajnantor. APEX, the largest submillimetre-wave telescope operating in the southern hemisphere, is a collaboration between the Max Planck Institute for Radio Astronomy, the Onsala Space Observatory and ESO. Operation of APEX at Chajnantor is entrusted to ESO. APEX is a “pathfinder” for ALMA — it is based on a prototype antenna constructed for the ALMA project, it is located on the same plateau and will find many targets that ALMA will be able to study in extreme detail.

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ESO is the European partner in ALMA. ALMA, the largest astronomical project in existence, is a revolutionary telescope, comprising an array of 66 giant 12-metre and 7-metre diameter antennas observing at millimetre and submillimetre wavelengths. ALMA will start scientific observations in 2011.

ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links

• The ATLASGAL paper referred to is available online at : http://www.aanda.org/10.1051/0004-6361/200811568/pdf
• More about APEX: http://www.eso.org/apex
• APEX handout: http://www.eso.org/public/outreach/products/publ/handouts/pdf/apex-lr.pdf
• Max-Planck Press Release in German: http://www.mpifr-bonn.mpg.de/public/pr/pr-atlasgal-dt.html

Source: ESO

Cosmic Protons Gone Wild

Supernova remnants act as giant, superefficient particle accelerators.

Credit: ESO/Eveline Helder et al./NASA/Chandra CXC

Shock waves launched into space by a supernova--the explosive death of a giant star--produce cosmic-ray particles carrying tremendous amounts of energy, astronomers have confirmed. The findings, reported today in Science, will give astronomers and physicists a better understanding of some of the universe's more bizarre phenomena.

Astronomers have suspected for more than a decade that supernova shock waves can act like giant particle accelerators. The basic idea is this: As the remnant of a dead star hurtles through space at up to 30 million kilometers per hour, it creates a shock wave as it interacts with the so-called interstellar medium (ISM). Protons in the shock wave get trapped by the magnetic field of the ISM, which bounces the protons back toward the remnant. But the remnant has its own magnetic field, which repels the protons.

Each bounce adds more energy, and eventually the magnetic tennis match accelerates the protons to nearly the speed of light. Knocked free of the remnant and out into deep space, some of the protons finally hit Earth's atmosphere. The particles are so energetic that astronauts have reported seeing flashes of light--caused by single protons striking their retinas--even when their eyes are closed.

Now an international team of astronomers has finally observed the acceleration of protons within a shock wave. Using the Very Large Telescope in Paranal, Chile, and NASA's Chandra spacecraft, they measured the visible light and x-ray emissions of the remnant of a supernova about 8200 light-years away in the direction of the constellation Circinus. These measurements, taken over several years, allowed them to calculate the energies of the protons behind and in front of the shock wave.

The results suggest that the remnant's energy accelerates protons as much as researchers had thought, says physicist and lead author Eveline Helder of Utrecht University in The Netherlands. "We did not expect such a high shock velocity," she says, referring to the speed of the protons in the shock wave. Based on that velocity, the team concludes that more than 50% of the energy of the shock wave must be going to accelerating the protons instead of generating heat.

It's an important paper, says physicist Donald Ellison of North Carolina State University in Raleigh. "It confirms predictions that shocks can be extremely efficient proton accelerators," he says, and it's going to improve understanding "of the physics of the universe's more exotic phenomenon," such as gamma-ray bursts and quasars, which also produce strong shock waves, as well as supernovae.

Read the whole article on Science NOW

Galaxies coming of age in cosmic blobs

Credit: Left panel: X-ray (NASA/CXC/Durham Univ./D.Alexander et al.); Optical (NASA/ESA/STScI/IoA/S.Chapman et al.); Lyman-alpha Optical (NAOJ/Subaru/Tohoku Univ./T.Hayashino et al.); Infrared (NASA/JPL-Caltech/Durham Univ./J.Geach et al.); Right, Illustration: NASA/CXC/M.Weiss

The "coming of age" of galaxies and black holes has been pinpointed, thanks to new data from NASA's Chandra X-ray Observatory and other telescopes. This discovery helps resolve the true nature of gigantic blobs of gas observed around very young galaxies. About a decade ago, astronomers discovered immense reservoirs of hydrogen gas -- which they named "blobs" – while conducting surveys of young distant galaxies. The blobs are glowing brightly in optical light, but the source of immense energy required to power this glow and the nature of these objects were unclear.

A long observation from Chandra has identified the source of this energy for the first time. The X-ray data show that a significant source of power within these colossal structures is from growing supermassive black holes partially obscured by dense layers of dust and gas. The fireworks of star formation in galaxies are also seen to play an important role, thanks to Spitzer Space Telescope and ground-based observations.

"For ten years the secrets of the blobs had been buried from view, but now we've uncovered their power source," said James Geach of Durham University in the United Kingdom, who led the study. "Now we can settle some important arguments about what role they played in the original construction of galaxies and black holes."

Galaxies are believed to form when gas flows inwards under the pull of gravity and cools by emitting radiation. This process should stop when the gas is heated by radiation and outflows from galaxies and their black holes. Blobs could be a sign of this first stage, or of the second.

Based on the new data and theoretical arguments, Geach and his colleagues show that heating of gas by growing supermassive black holes and bursts of star formation, rather than cooling of gas, most likely powers the blobs. The implication is that blobs represent a stage when the galaxies and black holes are just starting to switch off their rapid growth because of these heating processes. This is a crucial stage of the evolution of galaxies and black holes - known as "feedback" - and one that astronomers have long been trying to understand.

"We're seeing signs that the galaxies and black holes inside these blobs are coming of age and are now pushing back on the infalling gas to prevent further growth," said coauthor Bret Lehmer, also of Durham. "Massive galaxies must go through a stage like this or they would form too many stars and so end up ridiculously large by the present day."

Chandra and a collection of other telescopes including Spitzer have observed 29 blobs in one large field in the sky dubbed "SSA22." These blobs, which are several hundred thousand light years across, are seen when the Universe is only about two billion years old, or roughly 15% of its current age.

In five of these blobs, the Chandra data revealed the telltale signature of growing supermassive black holes - a point-like source with luminous X-ray emission. These giant black holes are thought to reside at the centers of most galaxies today, including our own. Another three of the blobs in this field show possible evidence for such black holes. Based on further observations, including Spitzer data, the research team was able to determine that several of these galaxies are also dominated by remarkable levels of star formation.

The radiation and powerful outflows from these black holes and bursts of star formation are, according to calculations, powerful enough to light up the hydrogen gas in the blobs they inhabit. In the cases where the signatures of these black holes were not detected, the blobs are generally fainter. The authors show that black holes bright enough to power these blobs would be too dim to be detected given the length of the Chandra observations.

Besides explaining the power source of the blobs, these results help explain their future. Under the heating scenario, the gas in the blobs will not cool down to form stars but will add to the hot gas found between galaxies. SSA22 itself could evolve into a massive galaxy cluster.

"In the beginning the blobs would have fed their galaxies, but what we see now are more like leftovers," said Geach. "This means we'll have to look even further back in time to catch galaxies and black holes in the act of forming from blobs."

Source: Chandra X-ray Center

Carbon couldn't light universe

The oldest carbon isn't in large enough
amounts to have been able to light up the
Universe, according to the researchers.

An international team of astronomers has discovered the oldest and most distant carbon in the Universe, but there's not enough of it to support standard theories of how the Universe lit up, a member from Swinburne University of Technology has calculated.

In the early Universe a dark pervasive fog of neutral hydrogen gas lurked everywhere. Astronomers think that this fog cleared when the first stars formed and emitted light.

There is a close connection between the amount of light and carbon produced in stars. But adding up all the 13-billion-year-old carbon detected, Dr Emma Ryan-Weber and her collaborators came to the conclusion the amount of carbon, and therefore the number of massive stars, was insufficient to lift the fog.

"So light must come from somewhere else, perhaps an unknown population of quasars, or stars that lock-up more of their carbon, or carbon hidden in unobserved states."

When the Universe began with the Big Bang only hydrogen and helium existed. After the first massive stars exploded as supernovae they sprinkled their products of carbon and other elements-of which you, I, and the Earth are comprised-all over the cosmos.

The researchers know the carbon they have discovered is old because it was detected in the infra-red wavelength rather than in the ultra-violet as on Earth. The Universe has expanded so much since the Big Bang, that the wavelength of the light from carbon atoms has stretched from 155 to 1085 nanometres by the time it reaches the Earth.

Even though astronomers have been observing intergalactic carbon for many years, no-one had tried to detect it in the early Universe, because this involved looking in the near-infra-red. Observations in the near-infra-red are challenging because of the interference of intense 'airglow' lines in the night sky.

The details surrounding the end of the dark Universe, a process know as 're-ionisation', are among the last mysteries of modern cosmology. Astronomers have yet to discover when the starlight from the first galaxies lit up the Universe, ionising the surrounding neutral hydrogen gas. And they don't know how massive these galaxies were, or whether they contained the same types of stars as we see today.

Even measurements suggesting the greatest number of galaxies in the early Universe could only lead to just enough light to lift the fog if the conditions are tweaked in the right way. Emma's survey of intergalactic carbon in the early Universe provides a completely independent measure of the amount of starlight.

"A lot more starlight is needed to lift the fog. It's like going from a visibility of a metre to being able to see a kilometre down the road."

Emma and her collaborators are planning further observations to search for carbon in a different state to see if it can make up the shortfall of starlight.

The observations of early carbon took place in collaboration with Prof. Piero Madau from the University of California at Santa Cruz, and Prof. Max Pettini and PhD student Berkeley Zych at Cambridge University in the UK. They used the European Southern Observatory's eight-metre Very Large Telescope in Chile as well as the 10-metre W.M. Keck Telescope in Hawaii. The results have recently been published in the Monthly Notices of the Royal Astronomical Society.

Betelgeuse, Red Supergiant In Constellation Orion, Has Shrunk By 15 Percent In 15 Years

ScienceDaily (June 16, 2009) — The red supergiant star Betelgeuse, the bright reddish star in the constellation Orion, has steadily shrunk over the past 15 years, according to University of California, Berkeley, researchers.

Long-term monitoring by UC Berkeley's Infrared Spatial Interferometer (ISI) on the top of Mt. Wilson in Southern California shows that Betelgeuse (bet' el juz), which is so big that in our solar system it would reach to the orbit of Jupiter, has shrunk in diameter by more than 15 percent since 1993.

Since Betelgeuse's radius is about five astronomical units, or five times the radius of Earth's orbit, that means the star's radius has shrunk by a distance equal to the orbit of Venus.

"To see this change is very striking," said Charles Townes, a UC Berkeley professor emeritus of physics who won the 1964 Nobel Prize in Physics for inventing the laser and the maser, a microwave laser. "We will be watching it carefully over the next few years to see if it will keep contracting or will go back up in size."

Townes and his colleague, Edward Wishnow, a research physicist at UC Berkeley's Space Sciences Laboratory, will discuss their findings at a 12:40 p.m. PDT press conference on Tuesday, June 9, during the Pasadena meeting of the American Astronomical Society (AAS). The results were published June 1 in The Astrophysical Journal Letters.

Despite Betelgeuse's diminished size, Wishnow pointed out that its visible brightness, or magnitude, which is monitored regularly by members of the American Association of Variable Star Observers, has shown no significant dimming over the past 15 years.

The ISI has been focusing on Betelgeuse for more than 15 years in an attempt to learn more about these giant massive stars and to discern features on the star's surface, Wishnow said. He speculated that the measurements may be affected by giant convection cells on the star's surface that are like convection granules on the sun, but so large that they bulge out of the surface. Townes and former graduate student Ken Tatebe observed a bright spot on the surface of Betelgeuse in recent years, although at the moment, the star appears spherically symmetrical.

"But we do not know why the star is shrinking," Wishnow said. "Considering all that we know about galaxies and the distant universe, there are still lots of things we don't know about stars, including what happens as red giants near the ends of their lives."

Betelgeuse was the first star ever to have its size measured, and even today is one of only a handful of stars that appears through the Hubble Space Telescope as a disk rather than a point of light. In1921, Francis G. Pease and Albert Michelson used optical interferometry to estimate its diameter was equivalent to the orbit of Mars. Last year, new measurements of the distance to Betelgeuse raised it from 430 light years to 640, which increased the star's diameter from about 3.7 to about 5.5 AU.

"Since the 1921 measurement, its size has been re-measured by many different interferometer systems over a range of wavelengths where the diameter measured varies by about 30 percent," Wishnow said. "At a given wavelength, however, the star has not varied in size much beyond the measurement uncertainties."

The measurements cannot be compared anyway, because the star's size depends on the wavelength of light used to measure it, Townes said. This is because the tenuous gas in the outer regions of the star emits light as well as absorbs it, which makes it difficult to determine the edge of the star.

The ISI that Townes and his colleagues first built in the early 1990s sidesteps these confounding emission and absorption lines by observing in the mid-infrared with a narrow bandwidth that can be tuned between spectral lines. The ISI consists of three 5.4-foot (1.65-meter) diameter mirrors separated by distances that vary from 12 to 230 feet (4-70 meters), said Townes. Using a laser as a common frequency standard, the ISI interferometer combines signals from telescope pairs in order to determine path length differences between light that originates at the star's center and light that originates at the star's edge. The technique of stellar interferometry is highlighted in the June 2009 issue of Physics Today magazine.

"We observe around 11 microns, the mid-infrared, where this long wavelength penetrates the dust and the narrow bandwidth avoids any spectral lines, and so we see the star relatively undistorted," said Townes. "We have also had the good fortune to have an instrument that has operated in a very similar manner for some 15 years, providing a long and consistent series of measurements that no one else has. The first measurements showed a size quite close to Michelson's result, but over 15 years, it has decreased in size about 15 percent, changing smoothly, but faster as the years progressed."

Townes, who turns 94 in July, plans to continue monitoring Betelgeuse in hopes of finding a pattern in the changing diameter, and to improve the ISI's capabilities by adding a spectrometer to the interferometer.

"Whenever you look at things with more precision, you are going to find some surprises and uncover very fundamental and important new things," he said.

The ISI is supported by grants from the National Science Foundation, the Gordon and Betty Moore Foundation and the Office of Naval Research.