Louisiana's coastline is changing — and changing fast, as you can see in the above map which shows the coastal land lost between 1922 and today. And the losses are only getting faster.
Sunday 31 August 2014
Friday 29 August 2014
"Detecting Alien Planet Particles Smaller than a Human Hair" --New SETI Breakthrough
It may sound like science fiction, but astronomers have worked out a scheme that will allow them to detect and measure particles ten times smaller than the width of a human hair, even at many light-years distance. They can do this by observing a blue tint in the light from far-off objects caused by the way in which small particles, no more than a micron in size (one-thousandth of a millimeter) scatter light.
In a recent study conducted by Adrian Brown of the SETI Institute, the broad outlines of this process have been worked out. “The effect is related to a familiar phenomenon known as Rayleigh scattering,” says Brown. “And that’s something everyone has seen: it makes the sky blue.”
By analyzing spectroscopic data from the Cassini orbiter, the Mars Reconnaissance Orbiter, and ground-based telescopes, Brown has managed to document this blue enhancement in many nearby objects, including the rings of Saturn, its moons Dione and Epimetheus, Mars, the moon, and the tail of Comet 17P/Holmes.
Brown’s theoretical study of the phenomenon showed that the spectral bluing occurs any time sufficiently small objects are in our field of view. In his studies, he considered particles between 0.1 and 1.0 microns in size. A human hair is roughly 17 microns in diameter.
So why isn’t the ground beneath our feet blue? Brown's research suggests that the effect is quickly damped by other objects that, despite being of the same type, have different size distributions. The effect depends on having many particles within a narrow range of size. In addition, too many tiny particles might turn objects white. As an example of the latter, a glass of milk appears white because of multiple scattering from fat globules, and clouds appear white due to multiple scattering from water aerosols (droplets).
Consequently, the bluing effect requires some process that forms lots of particles of almost identical size. Simply establishing that such a process is present can give researchers clues to the history and conditions on extraterrestrial bodies.
“This technique would, in principle, allow us to find extremely tiny particles in the atmospheres or on the surfaces of exoplanets that are tens or thousands of light-years away,” Brown says.
The research was published in the September 1 issue of Icarus.
Image at the top of the page shows exoplanet Gliese 832 c, around five times bigger than Earth [ PHL @ UPR Arecibo], and the closest one to Earth — a prime object for follow-up observations. Some experts think the Gliese 832c might be like the planet of Venus. Robert Wittenmyer of the University of New South Wales, who first spotted the planet, said: “Given the large mass of the planet, it seems likely that it would possess a massive atmosphere, which may well render the planet inhospitable. "Indeed, it is perhaps more likely that Gliese 832c is a 'super-Venus', featuring significant greenhouse forcing."
Supernova's Giant Thermonuclear Explosion Reveals Rare Isotope
Astrophysicists obtained for the first time spectra of radiating cobalt registered at the supernova SN2014J, shown above, located 11 million light-years from Earth. Isotope 56Co has a half-life of just 77 days, and does not exist in normal conditions. However, during a giant thermonuclear explosion of a supernova, this short-lived radioactive isotope is produced in large quantities. The reason was the rarity of explosions at such a distance – 11 million light-years is a large value on the galactic scale (the diameter of a galaxy is about 100,000 light-years, the distance between stars is a few light-years), but on an intergalactic scale it is a relatively short distance. There are several hundreds of galaxies within a radius of ten million light-years; supernovae produce explosions like this (type Ia explosions) once every few centuries in a galaxy, including a type Ia supernova that exploded in the Milky Way in 1606.
Yevgeny Churazov (Space Research Institute of the Russian Academy of Sciences), together with his co-authors, including Sergei Sazonov of the Space Research Institute and MIPT, reported the results of their analysis of data collected with the INTEGRAL gamma-ray orbital telescope, which they used to detect the radioactive isotope cobalt-56(56Co).
A radioactive decay chain and the spectrum obtained by the INTEGRAL observatory. Note the scale of the vertical axis – about one gamma quantum an hour per 1cm2! Image courtesy of the press service of the Nuclear Research Institute.
SN2014J was registered on January 21, 2014 by astronomer Steve Fossey and a group of students from University College London in the galaxy M82. Fossey reported the discovery, and several observatories, including INTEGRAL, started observations immediately. Russian researchers spent a million seconds of their quota for the use of the INTEGRAL telescope to study the supernova. In addition to the spectra, they obtained data on how the brightness of radiation changes over time.
According to a theory that was developed earlier, during an explosion of the Ia type, the remnants of a star barely radiate in the gamma range the first dozens of days. The star’s shell is opaque in this region of the spectrum; a supernova begins to produce gamma radiation only after the outer layer becomes sufficiently rarefied. By that time, radioactive nickel-56 with a half-life of 10 days, synthesized during the explosion, transforms into radioactive cobalt-56, the lines of which were detected by the researchers.
The essence of spectral analysis remains unchanged whatever the nature of radiation. For light, X-rays and even radio waves, scientists first plot a graph of a spectrum, or the relationship of intensity and frequency (or, equivalently, wavelength: wavelength is inversely proportional to frequency).
The graph’s shape indicates the nature of the source of radiation and through what environment the radiation has passed. Spectral lines, or sharp peaks on such graphs, correspond to certain events like the emission or absorption of quanta by atoms during transition from one energy level to another.
During formation, cobalt-56 had a surplus of energy, exhausted in the form of gamma rays with energies of 847 keV and 1237keV; other isotopes produced radiation with quanta of different energies and thus could not be confused with cobalt-56.
The data collected by the INTEGRAL telescope also allowed the researchers to assess how much radioactive cobalt was emitted during the explosion – the equivalent of about 60% of the Sun’s mass. Over time, cobalt-56 turns into the most common isotope of iron, 56Fe.56Fe is the most common isotope because it can be obtained from nickel emitted during supernovae explosions (nickel turns into cobalt, and cobalt turns into iron).
The new results back up simulations of supernovae explosions and also confirm that our planet consists of matter that has gone through thermonuclear explosions of an astronomical scale.
The Daily Galaxy via http://mipt.ru/
Thursday 28 August 2014
Vast Streams of Gravel Detected in Orion Molecular Cloud -- "A Long and Winding Road in Space Essential for Planet Formation"
Astronomers using the National Science Foundation’s (NSF) Green Bank Telescope (GBT) have discovered that filaments of star-forming gas near the Orion Nebula may be brimming with pebble-size particles -- planetary building blocks 100 to 1,000 times larger than the dust grains typically found around protostars. If confirmed, these dense ribbons of rocky material may well represent a new, mid-size class of interstellar particles that could help jump-start planet formation.
"The large dust grains seen by the GBT would suggest that at least some protostars may arise in a more nurturing environment for planets," said Scott Schnee, an astronomer with the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia. "After all, if you want to build a house, it’s best to start with bricks rather than gravel, and something similar can be said for planet formation."
The new GBT observations extend across the northern portion of the Orion Molecular Cloud Complex, a star-forming region that includes the famed Orion Nebula. The star-forming material in the section studied by the GBT, called OMC-2/3, has condensed into long, dust-rich filaments. The filaments are dotted with many dense knots known as cores. Some of the cores are just starting to coalesce while others have begun to form protostars -- the first early concentrations of dust and gas along the path to star formation. Astronomers speculate that in the next 100,000 to 1 million years, this area will likely evolve into a new star cluster. The OMC-2/3 region is located approximately 1,500 light-years from Earth and is roughly 10 light-years long.
Based on earlier maps of this region made with the IRAM 30 meter radio telescope in Spain, the astronomers expected to find a certain brightness to the dust emission when they observed the filaments at slightly longer wavelengths with the GBT.
Instead, the GBT discovered that the area was shining much brighter than expected in millimeter-wavelength light.
"This means that the material in this region has different properties than would be expected for normal interstellar dust,” noted Schnee. “In particular, since the particles are more efficient than expected at emitting at millimeter wavelengths, the grains are very likely to be at least a millimeter, and possibly as large as a centimeter across, or roughly the size of a small Lego-style building block."
Though incredibly small compared to even the most modest of asteroids, dust grains on the order of a few millimeters to a centimeter are incredibly large for such young star-forming regions. Due to the unique environment in the Orion Molecular Cloud Complex, the researchers propose two intriguing theories for their origin.
The first is that the filaments themselves helped the dust grains grow to such unusual proportions. These regions, compared to molecular clouds in general, have lower temperatures, higher densities, and lower velocities -- all of which would encourage grain growth.
The second scenario is that the rocky particles originally grew inside a previous generation of cores or perhaps even protoplanetary disks. The material could then have escaped back into the surrounding molecular cloud rather than becoming part of the original newly forming star system.
"Rather than typical interstellar dust, these researchers appear to have detected vast streamers of gravel -- essentially a long and winding road in space," said NRAO astronomer Jay Lockman, who was not involved in these observations. "We've known about dust specks and we have known that there are things the size of asteroids and planets, but if we can confirm these results it would add a new population of rocky particles to interstellar space."
The most recent data were taken with the Green Bank Telescope's high frequency imaging camera, MUSTANG. These data were compared with earlier studies as well as temperature estimates obtain from observations of ammonia molecules in the clouds.
"Though our results suggest the presence of unexpectedly large dust grains, measuring the mass of dust is not a straightforward process and there could be other explanations for the bright signature we detected in the emission from the Orion Molecular Cloud," concluded Brian Mason, an astronomer at the NRAO and co-author on the paper. "Our team continues to study this fascinating area. Since it contains one of the highest concentrations of protostars of any nearby molecular cloud it will continue to excite the curiosity of astronomers."
A paper detailing these results is accepted for publication in the Monthly Notices of the Royal Astronomical Society.
The GBT is the world's largest fully steerable radio telescope. Its location in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone protects the incredibly sensitive telescope from unwanted radio interference.
Later this year, the GBT will receive two new, more advanced high frequency cameras: MUSTANG-1.5, the even-more-sensitive successor to MUSTANG, and ARGUS, a camera designed for mapping the distribution of organic molecules in space.
The new GBT observations extend across the northern portion of the Orion Molecular Cloud Complex, a star-forming region that includes the famed Orion Nebula. The star-forming material in the section studied by the GBT, called OMC-2/3, has condensed into long, dust-rich filaments. The filaments are dotted with many dense knots known as cores. Some of the cores are just starting to coalesce while others have begun to form protostars -- the first early concentrations of dust and gas along the path to star formation. Astronomers speculate that in the next 100,000 to 1 million years, this area will likely evolve into a new star cluster. The OMC-2/3 region is located approximately 1,500 light-years from Earth and is roughly 10 light-years long.
Based on earlier maps of this region made with the IRAM 30 meter radio telescope in Spain, the astronomers expected to find a certain brightness to the dust emission when they observed the filaments at slightly longer wavelengths with the GBT.
Instead, the GBT discovered that the area was shining much brighter than expected in millimeter-wavelength light.
"This means that the material in this region has different properties than would be expected for normal interstellar dust,” noted Schnee. “In particular, since the particles are more efficient than expected at emitting at millimeter wavelengths, the grains are very likely to be at least a millimeter, and possibly as large as a centimeter across, or roughly the size of a small Lego-style building block."
Though incredibly small compared to even the most modest of asteroids, dust grains on the order of a few millimeters to a centimeter are incredibly large for such young star-forming regions. Due to the unique environment in the Orion Molecular Cloud Complex, the researchers propose two intriguing theories for their origin.
The first is that the filaments themselves helped the dust grains grow to such unusual proportions. These regions, compared to molecular clouds in general, have lower temperatures, higher densities, and lower velocities -- all of which would encourage grain growth.
The second scenario is that the rocky particles originally grew inside a previous generation of cores or perhaps even protoplanetary disks. The material could then have escaped back into the surrounding molecular cloud rather than becoming part of the original newly forming star system.
"Rather than typical interstellar dust, these researchers appear to have detected vast streamers of gravel -- essentially a long and winding road in space," said NRAO astronomer Jay Lockman, who was not involved in these observations. "We've known about dust specks and we have known that there are things the size of asteroids and planets, but if we can confirm these results it would add a new population of rocky particles to interstellar space."
The most recent data were taken with the Green Bank Telescope's high frequency imaging camera, MUSTANG. These data were compared with earlier studies as well as temperature estimates obtain from observations of ammonia molecules in the clouds.
"Though our results suggest the presence of unexpectedly large dust grains, measuring the mass of dust is not a straightforward process and there could be other explanations for the bright signature we detected in the emission from the Orion Molecular Cloud," concluded Brian Mason, an astronomer at the NRAO and co-author on the paper. "Our team continues to study this fascinating area. Since it contains one of the highest concentrations of protostars of any nearby molecular cloud it will continue to excite the curiosity of astronomers."
A paper detailing these results is accepted for publication in the Monthly Notices of the Royal Astronomical Society.
The GBT is the world's largest fully steerable radio telescope. Its location in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone protects the incredibly sensitive telescope from unwanted radio interference.
Later this year, the GBT will receive two new, more advanced high frequency cameras: MUSTANG-1.5, the even-more-sensitive successor to MUSTANG, and ARGUS, a camera designed for mapping the distribution of organic molecules in space.
Wednesday 27 August 2014
First Ever Observation of an Emerging Ancient Elliptical Galaxy --"Twice as Many Stars as Milky Way in a Region Only 6,000 Light Years Across"
A fully developed elliptical galaxy is a gas-deficient gathering of ancient stars theorized to develop from the inside out, with a compact core marking its beginnings. Astronomers have for the first time caught a glimpse of the earliest stages of massive galaxy construction. The building site is a dense galactic core blazing with the light of millions of newborn stars that are forming at a ferocious rate.
The discovery was made possible through combined observations from NASA’s Hubble and Spitzer space telescopes, the W.M. Keck Observatory in Mauna Kea, Hawaii, and the European Space Agency's Herschel space observatory, in which NASA plays an important role.Because the galactic core is so far away, the light of the forming galaxy that is observable from Earth was actually created 11 billion years ago, just 3 billion years after the Big Bang.
Although only a fraction of the size of the Milky Way, the tiny powerhouse galactic core already contains about twice as many stars as our own galaxy, all crammed into a region only 6,000 light-years across. The Milky Way is about 100,000 light-years across.
“I think our discovery settles the question of whether this mode of building galaxies actually happened or not,” said team-member Pieter van Dokkum of Yale University. “The question now is, how often did this occur? We suspect there are other galaxies like this that are even fainter in near-infrared wavelengths. We think they’ll be brighter at longer wavelengths, and so it will really be up to future infrared telescopes such as NASA’s James Webb Space Telescope to find more of these objects.”
“We really hadn’t seen a formation process that could create things that are this dense,” explained Erica Nelson of Yale University in New Haven, Connecticut, lead author of the study. “We suspect that this core-formation process is a phenomenon unique to the early universe because the early universe, as a whole, was more compact. Today, the universe is so diffuse that it cannot create such objects anymore.”
In addition to determining the galaxy’s size from the Hubble images, the team dug into archival far-infrared images from Spitzer and Herschel. This allowed them to see how fast the galaxy core is creating stars. Sparky produced roughly 300 stars per year, compared to the 10 stars per year produced by our Milky Way.
“They’re very extreme environments,” Nelson said. “It’s like a medieval cauldron forging stars. There’s a lot of turbulence, and it’s bubbling. If you were in there, the night sky would be bright with young stars, and there would be a lot of dust, gas, and remnants of exploding stars. To actually see this happening is fascinating.”
Astronomers theorize that this frenzied star birth was sparked by a torrent of gas flowing into the galaxy’s core while it formed deep inside a gravitational well of dark matter, invisible cosmic material that acts as the scaffolding of the universe for galaxy construction.
Observations indicate that the galaxy had been furiously making stars for more than a billion years. It is likely that this frenzy eventually will slow to a stop, and that over the next 10 billion years other smaller galaxies may merge with Sparky, causing it to expand and become a mammoth, sedate elliptical galaxy.
The image at the top pf the page shows a representative elliptical galaxy NGC 1132 and its surrounding region combines data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The blue/purple in the image is the x-ray glow from hot, diffuse gas detected by Chandra. Hubble's data reveal a giant foreground elliptical galaxy, plus numerous dwarf galaxies in its neighborhood, and many much more distant galaxies in the background.
Astronomers have dubbed NGC 1132 a "fossil group" because it contains an enormous amount of dark matter, comparable to the dark matter found in an entire group of galaxies. Also, the large amount of hot gas detected by Chandra is usually found for groups of galaxies, rather than a single galaxy.
The origin of such fossil-group systems remains a puzzle. They may be the end-products of the complete merging of groups of galaxies. Or, they may be very rare objects that formed in a region or period of time where the growth of moderate-sized galaxies was somehow suppressed, and only one large galaxy formed.
Elliptical galaxies are smooth and featureless. Containing hundreds of millions to trillions of stars, they range from nearly spherical to very elongated shapes. Their overall yellowish color comes from the aging stars. Because elliptical galaxies do not contain much cool gas, they can no longer make large numbers of new stars.
Although only a fraction of the size of the Milky Way, the tiny powerhouse galactic core already contains about twice as many stars as our own galaxy, all crammed into a region only 6,000 light-years across. The Milky Way is about 100,000 light-years across.
“I think our discovery settles the question of whether this mode of building galaxies actually happened or not,” said team-member Pieter van Dokkum of Yale University. “The question now is, how often did this occur? We suspect there are other galaxies like this that are even fainter in near-infrared wavelengths. We think they’ll be brighter at longer wavelengths, and so it will really be up to future infrared telescopes such as NASA’s James Webb Space Telescope to find more of these objects.”
“We really hadn’t seen a formation process that could create things that are this dense,” explained Erica Nelson of Yale University in New Haven, Connecticut, lead author of the study. “We suspect that this core-formation process is a phenomenon unique to the early universe because the early universe, as a whole, was more compact. Today, the universe is so diffuse that it cannot create such objects anymore.”
In addition to determining the galaxy’s size from the Hubble images, the team dug into archival far-infrared images from Spitzer and Herschel. This allowed them to see how fast the galaxy core is creating stars. Sparky produced roughly 300 stars per year, compared to the 10 stars per year produced by our Milky Way.
“They’re very extreme environments,” Nelson said. “It’s like a medieval cauldron forging stars. There’s a lot of turbulence, and it’s bubbling. If you were in there, the night sky would be bright with young stars, and there would be a lot of dust, gas, and remnants of exploding stars. To actually see this happening is fascinating.”
Astronomers theorize that this frenzied star birth was sparked by a torrent of gas flowing into the galaxy’s core while it formed deep inside a gravitational well of dark matter, invisible cosmic material that acts as the scaffolding of the universe for galaxy construction.
Observations indicate that the galaxy had been furiously making stars for more than a billion years. It is likely that this frenzy eventually will slow to a stop, and that over the next 10 billion years other smaller galaxies may merge with Sparky, causing it to expand and become a mammoth, sedate elliptical galaxy.
The image at the top pf the page shows a representative elliptical galaxy NGC 1132 and its surrounding region combines data from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The blue/purple in the image is the x-ray glow from hot, diffuse gas detected by Chandra. Hubble's data reveal a giant foreground elliptical galaxy, plus numerous dwarf galaxies in its neighborhood, and many much more distant galaxies in the background.
Astronomers have dubbed NGC 1132 a "fossil group" because it contains an enormous amount of dark matter, comparable to the dark matter found in an entire group of galaxies. Also, the large amount of hot gas detected by Chandra is usually found for groups of galaxies, rather than a single galaxy.
The origin of such fossil-group systems remains a puzzle. They may be the end-products of the complete merging of groups of galaxies. Or, they may be very rare objects that formed in a region or period of time where the growth of moderate-sized galaxies was somehow suppressed, and only one large galaxy formed.
Elliptical galaxies are smooth and featureless. Containing hundreds of millions to trillions of stars, they range from nearly spherical to very elongated shapes. Their overall yellowish color comes from the aging stars. Because elliptical galaxies do not contain much cool gas, they can no longer make large numbers of new stars.
Tuesday 26 August 2014
Is Our 3-D Universe an Illusion? --"Everything Could Actually be Encoded in Tiny packets in Two Dimensions"
“We want to find out whether spacetime is a quantum system just like matter is,” said Craig Hogan, director of Fermilab’s Center for Particle Astrophysics and the developer of the holographic noise theory. “If we see something, it will completely change ideas about space we’ve used for thousands of years.”
Much like characters on a television show would not know that their seemingly 3 - D world exists only on a 2 - D screen, we could be clueless that our 3 - D space is just an illusion. The information about everything in our universe could actually be encoded in tiny packets in two dimensions. A unique experiment at the U.S. Department of Energy’s Fermi National Accelerator Laboratory called the Holometer has started collecting data that will answer some mind-bending questions about our universe – including whether we live in a hologram.
Get close enough to your TV screen and you’ll see pixels, small points of data that make a seamless image if you stand back. Scientists think that the universe’s information may be contained in the same way, and that the natural “pixel size” of space is roughly 10 trillion trillion times smaller than an atom, a distance that physicists refer to as the Planck scale.
Quantum theory suggests that it is impossible to know both the exact location and the exact speed of subatomic particles. If space comes in 2-D bits with limited information about the precise location of objects, then space itself would fall under the same theory of uncertainty . The same way that matter continues to jiggle (as quantum waves) even when cooled to absolute zero, this digitized space should have built-in vibrations even in its lowest energy state.
Essentially, the experiment probes the limits of the universe’s ability to store information. If there are a set number of bits that tell you where something is, it eventually becomes impossible to find more specific information about the location – even in principle. The instrument testing these limits is Fermilab’s Holometer, or holographic interferometer, the most sensitive device ever created to measure the quantum jitter of space itself.
Now operating at full power, the Holometer uses a pair of interferometers placed close to one another. Each one sends a one-kilowatt laser beam (the equivalent of 200,000 laser pointers) at a beam splitter and down two perpendicular 40-meter arms. The light is then reflected back to the beam splitter where the two beams recombine, creating fluctuations in brightness if there is motion. Researchers analyze these fluctuations in the returning light to see if the beam splitter is moving in a certain way – being carried along on a jitter of space itself.
“Holographic noise” is expected to be present at all frequencies, but the scientists’ challenge is not to be fooled by other sources of vibrations. The Holometer is testing a frequency so high – millions of cycles per second – that motions of normal matter are not likely to cause problems. Rather, the dominant background noise is more often due to radio waves emitted by nearby electronics. The Holometer experiment is designed to identify and eliminate noise from such conventional sources.
“If we find a noise we can’t get rid of, we might be detecting something fundamental about nature–a noise that is intrinsic to spacetime,” said Fermilab physicist Aaron Chou, lead scientist and project manager for the Holometer. “It’s an exciting moment for physics. A positive result will open a whole new avenue of questioning about how space works."
In the image at the top of the page, astronomers using the NASA/ESA Hubble Space Telescope have studied a giant filament of dark matter in 3D for the first time. Extending 60 million light-years from one of the most massive galaxy clusters known, the filament is part of the cosmic web that constitutes the large-scale structure of the Universe, and is a leftover of the very first moments after the Big Bang. If the high mass measured for the filament is representative of the rest of the Universe, then these structures may contain more than half of all the mass in the Universe.
The Holometer experiment, funded by the U.S. Department of Energy Office of Science and other sources, is expected to gather data over the coming year.
The Holometer team comprises 21 scientists and students from Fermilab, Massachusetts Institute of Technology, University of Chicago, and University of Michigan. For more information about the experiment, visit http://ift.tt/wpwHrh .
Get close enough to your TV screen and you’ll see pixels, small points of data that make a seamless image if you stand back. Scientists think that the universe’s information may be contained in the same way, and that the natural “pixel size” of space is roughly 10 trillion trillion times smaller than an atom, a distance that physicists refer to as the Planck scale.
Quantum theory suggests that it is impossible to know both the exact location and the exact speed of subatomic particles. If space comes in 2-D bits with limited information about the precise location of objects, then space itself would fall under the same theory of uncertainty . The same way that matter continues to jiggle (as quantum waves) even when cooled to absolute zero, this digitized space should have built-in vibrations even in its lowest energy state.
Essentially, the experiment probes the limits of the universe’s ability to store information. If there are a set number of bits that tell you where something is, it eventually becomes impossible to find more specific information about the location – even in principle. The instrument testing these limits is Fermilab’s Holometer, or holographic interferometer, the most sensitive device ever created to measure the quantum jitter of space itself.
Now operating at full power, the Holometer uses a pair of interferometers placed close to one another. Each one sends a one-kilowatt laser beam (the equivalent of 200,000 laser pointers) at a beam splitter and down two perpendicular 40-meter arms. The light is then reflected back to the beam splitter where the two beams recombine, creating fluctuations in brightness if there is motion. Researchers analyze these fluctuations in the returning light to see if the beam splitter is moving in a certain way – being carried along on a jitter of space itself.
“Holographic noise” is expected to be present at all frequencies, but the scientists’ challenge is not to be fooled by other sources of vibrations. The Holometer is testing a frequency so high – millions of cycles per second – that motions of normal matter are not likely to cause problems. Rather, the dominant background noise is more often due to radio waves emitted by nearby electronics. The Holometer experiment is designed to identify and eliminate noise from such conventional sources.
“If we find a noise we can’t get rid of, we might be detecting something fundamental about nature–a noise that is intrinsic to spacetime,” said Fermilab physicist Aaron Chou, lead scientist and project manager for the Holometer. “It’s an exciting moment for physics. A positive result will open a whole new avenue of questioning about how space works."
In the image at the top of the page, astronomers using the NASA/ESA Hubble Space Telescope have studied a giant filament of dark matter in 3D for the first time. Extending 60 million light-years from one of the most massive galaxy clusters known, the filament is part of the cosmic web that constitutes the large-scale structure of the Universe, and is a leftover of the very first moments after the Big Bang. If the high mass measured for the filament is representative of the rest of the Universe, then these structures may contain more than half of all the mass in the Universe.
The Holometer experiment, funded by the U.S. Department of Energy Office of Science and other sources, is expected to gather data over the coming year.
The Holometer team comprises 21 scientists and students from Fermilab, Massachusetts Institute of Technology, University of Chicago, and University of Michigan. For more information about the experiment, visit http://ift.tt/wpwHrh .
"When the Visible Universe was Less than One Microsecond Old" --Researchers Simulate Birth of the Cosmos
When the universe was less than one microsecond old and more than one trillion degrees, it transformed from a plasma of quarks and gluons into bound states of quarks - also known as protons and neutrons, the fundamental building blocks of ordinary matter that make up most of the visible universe.
Using a calculation originally proposed seven years ago to be performed on a petaflop computer, Lawrence Livermore researchers computed conditions that simulate the birth of the universe. The theory of quantum chromodynamics (QCD) governs the interactions of the strong nuclear force and predicts it should happen when such conditions occur.
In a paper appearing in the Aug. 18 edition of Physical Review Letters, Lawrence Livermore scientists Chris Schroeder, Ron Soltz and Pavlos Vranas calculated the properties of the QCD phase transition using LLNL's Vulcan, a five-petaflop machine. This work was done within the LLNL-led HotQCD Collaboration, involving Los Alamos National Laboratory, Institute for Nuclear Theory, Columbia University, Central China Normal University, Brookhaven National Laboratory and Universität Bielefed in Germany.
This is the first time that this calculation has been performed in a way that preserves a certain fundamental symmetry of the QCD, in which the right and left-handed quarks (scientists call this chirality) can be interchanged without altering the equations. These important symmetries are easy to describe, but they are computationally very challenging to implement.
"But with the invention of petaflop computing, we were able to calculate the properties with a theory proposed years ago when petaflop-scale computers weren't even around yet," Soltz said.
The research has implications for our understanding of the evolution of the universe during the first microsecond after the Big Bang, when the universe expanded and cooled to a temperature below 10 trillion degrees.
Below this temperature, quarks and gluons are confined, existing only in hadronic bound states such as the familiar proton and neutron. Above this temperature, these bound states cease to exist and quarks and gluons instead form plasma, which is strongly coupled near the transition and coupled more and more weakly as the temperature increases.
"The result provides an important validation of our understanding of the strong interaction at high temperatures, and aids us in our interpretation of data collected at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN." Soltz said.
Soltz and Pavlos Vranas, along with former colleague Thomas Luu, wrote an essay predicting that if there were powerful enough computers, the QCD phase transition could be calculated. The essay was published in Computing in Science & Engineering in 2007, "back when a petaflop really did seem like a lot of computing," Soltz said. "With the invention of petaflop computers, the calculation took us several months to complete, but the 2007 estimate turned out to be pretty close."
The extremely computationally intensive calculation was made possible through a Grand Challenge allocation of time on the Vulcan Blue Gene/Q Supercomputer at Lawrence Livermore National Laboratory.
In a paper appearing in the Aug. 18 edition of Physical Review Letters, Lawrence Livermore scientists Chris Schroeder, Ron Soltz and Pavlos Vranas calculated the properties of the QCD phase transition using LLNL's Vulcan, a five-petaflop machine. This work was done within the LLNL-led HotQCD Collaboration, involving Los Alamos National Laboratory, Institute for Nuclear Theory, Columbia University, Central China Normal University, Brookhaven National Laboratory and Universität Bielefed in Germany.
This is the first time that this calculation has been performed in a way that preserves a certain fundamental symmetry of the QCD, in which the right and left-handed quarks (scientists call this chirality) can be interchanged without altering the equations. These important symmetries are easy to describe, but they are computationally very challenging to implement.
"But with the invention of petaflop computing, we were able to calculate the properties with a theory proposed years ago when petaflop-scale computers weren't even around yet," Soltz said.
The research has implications for our understanding of the evolution of the universe during the first microsecond after the Big Bang, when the universe expanded and cooled to a temperature below 10 trillion degrees.
Below this temperature, quarks and gluons are confined, existing only in hadronic bound states such as the familiar proton and neutron. Above this temperature, these bound states cease to exist and quarks and gluons instead form plasma, which is strongly coupled near the transition and coupled more and more weakly as the temperature increases.
"The result provides an important validation of our understanding of the strong interaction at high temperatures, and aids us in our interpretation of data collected at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory and the Large Hadron Collider at CERN." Soltz said.
Soltz and Pavlos Vranas, along with former colleague Thomas Luu, wrote an essay predicting that if there were powerful enough computers, the QCD phase transition could be calculated. The essay was published in Computing in Science & Engineering in 2007, "back when a petaflop really did seem like a lot of computing," Soltz said. "With the invention of petaflop computers, the calculation took us several months to complete, but the 2007 estimate turned out to be pretty close."
The extremely computationally intensive calculation was made possible through a Grand Challenge allocation of time on the Vulcan Blue Gene/Q Supercomputer at Lawrence Livermore National Laboratory.
Monday 25 August 2014
Saturn's Titan --"The 'Rosetta Stone' of Prebiotic Chemistry and the Origin of Life?”
Luckily for researchers, there is a possible laboratory in our solar system to help us better understand the conditions on Earth before life arose — a situation sometimes referred to as a “prebiotic” environment. That location is Titan, the largest moon of Saturn, that has fascinated researchers for decades, particularly after NASA’s Voyager 1 and Voyager 2 spacecraft flew by Saturn in the 1980s. The missions revealed a moon completely socked in with haze, which is a different experience to those used to gazing at Earth’s airless, cratered moon.
A recent finding revealed that Titan’s atmosphere is likely older than that of Saturn. This suggests that the moon did not arise from the ringed gas giant, but instead was created separately in the gas and dust floating around the young Solar System while the Sun and planets were being formed.
A closer look came in 2004, when the Cassini-Huygens mission arrived to study the system. Since then, the spacecraft has done hundreds of flybys of Titan and peered at its surface by penetrating the clouds with radar. The European Space Agency’s Huygens lander also made a soft landing on the moon in 2005.
One of the big research questions is the composition of the haze. A new study is trying to recreate substances in the atmosphere called tholins, organic aerosols which are produced when radiation bakes the nitrogen and methane-rich atmosphere. In some cases, organics are considered precursors to life.
“The study of organic chemistry on Titan’s surface would extend our understanding of the diversity of prebiotic chemistry, and perhaps life’s origin on Earth,” said Dr. Chao He, a chemist at the University of Houston (now moved to Johns Hopkins University) who led the study.
The results were publishedas “Solubility and stability investigation of Titan aerosol analogs: New insight from NMR analysis” in the journal Icarus.
According to He, the study of Titan’s tholins help scientists understand the basic properties of organic materials on Titan. Questions to consider include how they are structured, whether the aerosols can be dissolved in liquid in Titan’s surface or atmosphere, and how stable the organics could be. Titan’s tholins are thought to contain chemical precursors of life, and studying the molecule’s structure helps scientists better understand whether life’s possible precursors have formed on Titan. If they have formed, the solubility study helps to hint where to find them on Titan, and the stability study suggests the most capable detection methods.
The tholins were created by making a mix of methane (5 percent) and nitrogen (95 percent) in a reaction chamber at room temperature. The mixture was exposed to an electrical discharge for 72 hours, which then created a muddy substance — the tholin — on the walls of the vessel. The substances produced had a similar optical appearance to what Cassini observed in Titan’s atmosphere.
Researchers then investigated how well the tholins would dissolve in a solvent. Several solvents were investigated, including polar solvents (methanol, water, dimethyl sulfoxide and acetonitrile) and non-polar solvents (pentane, benzene and cyclohexane). Polar solvents usually have different electrical charges between atoms (such as positive-charged oxygen and negative-charged hydrogen, in water) while non-polar solvents have similar electrical charges between atoms. Generally, polar solvents dissolve polar compounds best and non-polar solvents dissolve non-polar compounds best.
The researchers found that the tholins preferentially dissolves in polar solvents, suggesting little or none of the substance would be dissolved in the lakes or oceans on Titan, which are consist of non-polar ethane/methane. Thus, the tholins should be on the surface of the land or at the bottom of the lakes and oceans, He noted.
“The tholin preferentially dissolves in polar solvents, alsosuggesting the tholins are composed of a large percentage of polar species,” Headded.
The Huygens probe only survived on the surface of Titan for a few hours, but there are proposals out there to do extended missions. One example is a NASA Innovative Advanced Concepts proposal to send a submarine to explore Titan’s lakes. The proposal is at the first stage of investigation and would be decades away to launch, if funding is approved.
If researchers were looking for tholins with a surface or underwater craft on Titan, He’s study could help narrow down the location. Tholins break down in hot temperatures, but this is not a problem for Titan’s surface, which sees an average surface temperature of -179 degrees Celsius (-290 degrees Fahrenheit).
Future landing missions, however, might have to contend with avoiding heating the tholins to look at their structure, and instead should focus on nondestructive instruments and methods to accomplish this, He said. Possible methods of detecting organics could be liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR). Both methods can provide detailed structural information of organic mixtures nondestructively.
In the midst of this analysis, His team developed a new method to study the solubility of tholins. They found several nitrogenated organic molecules in Titan tholins. “Some of them are very important to the prebiotic chemistry and the origin of life,” He said.
“My research focuses on the astrobiology on potential environments and objects,” He said. “Titan is an important one. This study helps to understand the basic properties of organics on Titan. It also provides the basis for the development of in situ analysis of methods and instruments for a Titan mission and other outer planet exploration.”
He plans to continue his study of organic chemistry on Titan, and then extend that understanding to other potentially interesting environments for life in the Solar System, such as Mars, Jupiter’s icy moon Europa or Saturn’s moon Enceladus, which has been recorded spouting water-rich plumes into the atmosphere.
Scientists’ understanding of Titan is constantly changing as the Cassini-Huygens mission beams back data from the distant moon. For example, in 2007 scientists discovered that the tholins form at much higher altitudes than previously believed, at greater than 1,000 kilometers (621 miles) as opposed to a few hundred kilometers above the ground.
The results also revealed an unexpected high number of ions (negatively charged atoms) among the clouds of the moon, as well as detecting benzene, an element that is required to put together the tholins.
“The negative ions were a complete surprise,” stated David Young, a scientist at the Southwest Research Institute in Texas, who led the Cassini Plasma Spectrometer (CAPS) investigation. “This suggests they may play an unexpected role in making tholins from carbon-nitrogen precursors.”
A closer look came in 2004, when the Cassini-Huygens mission arrived to study the system. Since then, the spacecraft has done hundreds of flybys of Titan and peered at its surface by penetrating the clouds with radar. The European Space Agency’s Huygens lander also made a soft landing on the moon in 2005.
One of the big research questions is the composition of the haze. A new study is trying to recreate substances in the atmosphere called tholins, organic aerosols which are produced when radiation bakes the nitrogen and methane-rich atmosphere. In some cases, organics are considered precursors to life.
“The study of organic chemistry on Titan’s surface would extend our understanding of the diversity of prebiotic chemistry, and perhaps life’s origin on Earth,” said Dr. Chao He, a chemist at the University of Houston (now moved to Johns Hopkins University) who led the study.
The results were publishedas “Solubility and stability investigation of Titan aerosol analogs: New insight from NMR analysis” in the journal Icarus.
According to He, the study of Titan’s tholins help scientists understand the basic properties of organic materials on Titan. Questions to consider include how they are structured, whether the aerosols can be dissolved in liquid in Titan’s surface or atmosphere, and how stable the organics could be. Titan’s tholins are thought to contain chemical precursors of life, and studying the molecule’s structure helps scientists better understand whether life’s possible precursors have formed on Titan. If they have formed, the solubility study helps to hint where to find them on Titan, and the stability study suggests the most capable detection methods.
The tholins were created by making a mix of methane (5 percent) and nitrogen (95 percent) in a reaction chamber at room temperature. The mixture was exposed to an electrical discharge for 72 hours, which then created a muddy substance — the tholin — on the walls of the vessel. The substances produced had a similar optical appearance to what Cassini observed in Titan’s atmosphere.
Researchers then investigated how well the tholins would dissolve in a solvent. Several solvents were investigated, including polar solvents (methanol, water, dimethyl sulfoxide and acetonitrile) and non-polar solvents (pentane, benzene and cyclohexane). Polar solvents usually have different electrical charges between atoms (such as positive-charged oxygen and negative-charged hydrogen, in water) while non-polar solvents have similar electrical charges between atoms. Generally, polar solvents dissolve polar compounds best and non-polar solvents dissolve non-polar compounds best.
The researchers found that the tholins preferentially dissolves in polar solvents, suggesting little or none of the substance would be dissolved in the lakes or oceans on Titan, which are consist of non-polar ethane/methane. Thus, the tholins should be on the surface of the land or at the bottom of the lakes and oceans, He noted.
“The tholin preferentially dissolves in polar solvents, alsosuggesting the tholins are composed of a large percentage of polar species,” Headded.
The Huygens probe only survived on the surface of Titan for a few hours, but there are proposals out there to do extended missions. One example is a NASA Innovative Advanced Concepts proposal to send a submarine to explore Titan’s lakes. The proposal is at the first stage of investigation and would be decades away to launch, if funding is approved.
If researchers were looking for tholins with a surface or underwater craft on Titan, He’s study could help narrow down the location. Tholins break down in hot temperatures, but this is not a problem for Titan’s surface, which sees an average surface temperature of -179 degrees Celsius (-290 degrees Fahrenheit).
Future landing missions, however, might have to contend with avoiding heating the tholins to look at their structure, and instead should focus on nondestructive instruments and methods to accomplish this, He said. Possible methods of detecting organics could be liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance spectroscopy (NMR). Both methods can provide detailed structural information of organic mixtures nondestructively.
In the midst of this analysis, His team developed a new method to study the solubility of tholins. They found several nitrogenated organic molecules in Titan tholins. “Some of them are very important to the prebiotic chemistry and the origin of life,” He said.
“My research focuses on the astrobiology on potential environments and objects,” He said. “Titan is an important one. This study helps to understand the basic properties of organics on Titan. It also provides the basis for the development of in situ analysis of methods and instruments for a Titan mission and other outer planet exploration.”
He plans to continue his study of organic chemistry on Titan, and then extend that understanding to other potentially interesting environments for life in the Solar System, such as Mars, Jupiter’s icy moon Europa or Saturn’s moon Enceladus, which has been recorded spouting water-rich plumes into the atmosphere.
Scientists’ understanding of Titan is constantly changing as the Cassini-Huygens mission beams back data from the distant moon. For example, in 2007 scientists discovered that the tholins form at much higher altitudes than previously believed, at greater than 1,000 kilometers (621 miles) as opposed to a few hundred kilometers above the ground.
The results also revealed an unexpected high number of ions (negatively charged atoms) among the clouds of the moon, as well as detecting benzene, an element that is required to put together the tholins.
“The negative ions were a complete surprise,” stated David Young, a scientist at the Southwest Research Institute in Texas, who led the Cassini Plasma Spectrometer (CAPS) investigation. “This suggests they may play an unexpected role in making tholins from carbon-nitrogen precursors.”
Thursday 21 August 2014
Image of the Day: Neptune's Strange Moon Triton
Composite view showing Neptune on Triton's horizon. Neptune's south pole is to the left; clearly visible in the planets' southern hemisphere is a Great Dark Spot, a large anticyclonic storm system located about 20 degrees South. The foreground is a computer generated view of Triton's maria as they would appear from a point approximately 45 km above the surface. The terraces visible in this image indicate multiple episodes of 'cryovolcanic' flooding. This three-dimensional view was created from a Voyager image by using a two-dimensional photoclinometric model. Relief has been exaggerated roughly 30-fold, the actual range of the relief is about 1 km.
Would Neptune appear to be rising or setting? Neither, due to the motion of Triton relative to Neptune, it would appear to move laterally along the horizon, eventually rising and setting at high latitudes.
The image above is from the Voyager 2 spacecraft fly by of Triton in the summer of 1989. Dr. Paul Schenk, a scientist at the Lunar and Planetary Institute in Houston, used Voyager data to construct the best-ever global color map of Triton. This map has a resolution of 1,970 feet (600 meters) per pixel. The colors have been enhanced to bring out contrast but are a close approximation to Triton's natural colors. Voyager's "eyes" saw in colors slightly different from human eyes, and this map was produced using orange, green and blue filter images.
The image above is from the Voyager 2 spacecraft fly by of Triton in the summer of 1989. Dr. Paul Schenk, a scientist at the Lunar and Planetary Institute in Houston, used Voyager data to construct the best-ever global color map of Triton. This map has a resolution of 1,970 feet (600 meters) per pixel. The colors have been enhanced to bring out contrast but are a close approximation to Triton's natural colors. Voyager's "eyes" saw in colors slightly different from human eyes, and this map was produced using orange, green and blue filter images.
Origins of Jupiter's Vast Magnetic Field Deciphered
Superlatives are the trademark of the planet Jupiter. The magnetic field at the top edge of the cloud surrounding the largest member of the solar system is around ten times stronger than Earth’s, and is by far the largest magnetosphere around a planet in our Solar System. Just why this field has a similar structure to that of our own planet although the interiors of the two celestial objects have a completely different structure, has mystified researchers for a long time.
With the aid of the most detailed computer simulations to date, a team headed by the Max Planck Institute for Solar System Research in Göttingen has now succeeded in explaining the origin of the magnetic field deep inside the gaseous giant.
Jupiter autopsy: The magnetic field lines illustrate the high complexity of the magnetic field inside the planet, which, however, quickly decreases beyond the metallic layer (black line). On the surface, a dipolar part that is inclined by ten degrees with respect to the axis of rotation dominates. The thickness of the field lines is a measure of the local magnetic field strength. In the equatorial region, a jet produces bundles of field lines with a pronounced east-west orientation at the transition to the metallic layer. The colored contours represent the radial surface field. Red indicates field lines directed outwards, blue inwards; green denotes a weak field. The colour coding of the sections represents the field in the east-west direction – red indicates eastwards, blue westwards.
Magnetic fields are always generated when electric currents flow. The Earth is surrounded by a magnetic field because, deep in its interior, there is a circulating molten mass of iron and nickel. This motion gives rise to electric currents that generate Earth’s familiar dipolar magnetic field, in much the same way as a bicycle dynamo operates. Physicists call it the geo-dynamo. But how does the dynamo inside of Jupiter work?
Jupiter consists predominantly of hydrogen and helium. Photos of the planet show coloured bands of cloud and gigantic tornados such as the Great Red Spot. The temperature at the upper cloud boundary is minus 100 degrees Celsius, but temperature, pressure and electrical conductivity increase enormously with increasing depth.
At a depth of just under 10,000 kilometres and a pressure of several million atmospheres, the hydrogen even becomes conductive like a metal – an exotic state of matter which does not exist on Earth. It is still unclear whether there is a rocky core at the centre of the planet; it could possibly amount to around 20 percent of the Jupiter radius – corresponding to 14,000 kilometres.
Previous computer simulations on the formation of the magnetic field had to greatly simplify this complex structure. The upper gaseous region and the lower metallic region were treated separately, for example. Thus, no computation correctly reproduced the strength and the form of the magnetic field as determined by space probes.
“Several colleagues assumed that certain physical quantities changed suddenly at the transition to the region of the metal-like conducting hydrogen,” says project leader Johannes Wicht from the Max Planck Institute for Solar System Research in Göttingen. But new models from colleagues at the University of Rostock seem to prove that this is probably not the case. The properties change gradually over the whole gas layer so that the separate treatment of the outer and inner region is hardly justified.
The important step forward here was the fact that, for the first time, the Göttingen-based physicists dealt with all regions of the planet in the same simulation. To this effect, the Max Planck Society’s huge Hydra supercomputer in Garching had to spend around six months on the computation.
The result was impressive: it portrayed Jupiter’s magnetic field more or less as space probes had determined it in nature. “The main part of the magnetic field, which looks so similar to Earth’s magnetic field, is generated deep inside the planet, where the properties no longer change so strongly,” says Wicht.
The new simulations indicate that a second, weaker dynamo is also active, however. It operates in the transition zone to the metallic layer near the equator. It is brought about by a strong wind blowing towards the east, a so-called jet, which can be recognised from the cloud movements. In the outer, cool regions of the atmosphere it is not yet possible for a magnetic field to be generated, as the conductivity here is too low.
But at greater depths the temperature rises, and from around 8,000 kilometres below the cloud cover, the electrical conductivity, thanks to the formation of plasma, is high enough for the dynamo to start.
“Crucial here is the product of wind speed and electrical conductivity,” explains Moritz Heimpel from the University of Alberta in Edmonton, Canada. As soon as it exceeds a specific value, a magnetic field can form. “The jet shears the magnetic field in the east-west direction and produces a characteristic magnetic band structure in the equatorial region,” says Thomas Gastine, a staff member at the Max Planck Institute for Solar System Research.
“In order to portray the special properties of the two dynamo processes involved, it was particularly important to model the interior properties of the planet as accurately as possible,” adds Lucia Duarte, who carried out the first computation during her doctoral work at the Max Planck Institute in Göttingen.
Hence, two magnetic fields form, which superimpose: the Earth-like one in the deep layer of the metal-like conducting hydrogen, and the weaker band structure generated by the equatorial jet. “The Earth-like field corresponds in strength and structure to the measurement data to date provided by space probes, which do not allow the band structure to be resolved,” says Thomas Gastine.
The simulations span a period of around 6,500 years and also reveal changes. The field strength should vary, for example, and the inclination of the axis should change by around 0.02 degrees per year. It will soon be possible for the Juno space probe to check this and further properties predicted by the new model.
The American space craft was launched three years ago and is due to enter into an orbit around the giant planet in August 2016. “With the new measurement data, we will find out much more about the inner structure and the magnetic field than has been possible to date, and can hopefully confirm the band structures as well,” says Johannes Wicht.
Jupiter autopsy: The magnetic field lines illustrate the high complexity of the magnetic field inside the planet, which, however, quickly decreases beyond the metallic layer (black line). On the surface, a dipolar part that is inclined by ten degrees with respect to the axis of rotation dominates. The thickness of the field lines is a measure of the local magnetic field strength. In the equatorial region, a jet produces bundles of field lines with a pronounced east-west orientation at the transition to the metallic layer. The colored contours represent the radial surface field. Red indicates field lines directed outwards, blue inwards; green denotes a weak field. The colour coding of the sections represents the field in the east-west direction – red indicates eastwards, blue westwards.
Magnetic fields are always generated when electric currents flow. The Earth is surrounded by a magnetic field because, deep in its interior, there is a circulating molten mass of iron and nickel. This motion gives rise to electric currents that generate Earth’s familiar dipolar magnetic field, in much the same way as a bicycle dynamo operates. Physicists call it the geo-dynamo. But how does the dynamo inside of Jupiter work?
Jupiter consists predominantly of hydrogen and helium. Photos of the planet show coloured bands of cloud and gigantic tornados such as the Great Red Spot. The temperature at the upper cloud boundary is minus 100 degrees Celsius, but temperature, pressure and electrical conductivity increase enormously with increasing depth.
At a depth of just under 10,000 kilometres and a pressure of several million atmospheres, the hydrogen even becomes conductive like a metal – an exotic state of matter which does not exist on Earth. It is still unclear whether there is a rocky core at the centre of the planet; it could possibly amount to around 20 percent of the Jupiter radius – corresponding to 14,000 kilometres.
Previous computer simulations on the formation of the magnetic field had to greatly simplify this complex structure. The upper gaseous region and the lower metallic region were treated separately, for example. Thus, no computation correctly reproduced the strength and the form of the magnetic field as determined by space probes.
“Several colleagues assumed that certain physical quantities changed suddenly at the transition to the region of the metal-like conducting hydrogen,” says project leader Johannes Wicht from the Max Planck Institute for Solar System Research in Göttingen. But new models from colleagues at the University of Rostock seem to prove that this is probably not the case. The properties change gradually over the whole gas layer so that the separate treatment of the outer and inner region is hardly justified.
The important step forward here was the fact that, for the first time, the Göttingen-based physicists dealt with all regions of the planet in the same simulation. To this effect, the Max Planck Society’s huge Hydra supercomputer in Garching had to spend around six months on the computation.
The result was impressive: it portrayed Jupiter’s magnetic field more or less as space probes had determined it in nature. “The main part of the magnetic field, which looks so similar to Earth’s magnetic field, is generated deep inside the planet, where the properties no longer change so strongly,” says Wicht.
The new simulations indicate that a second, weaker dynamo is also active, however. It operates in the transition zone to the metallic layer near the equator. It is brought about by a strong wind blowing towards the east, a so-called jet, which can be recognised from the cloud movements. In the outer, cool regions of the atmosphere it is not yet possible for a magnetic field to be generated, as the conductivity here is too low.
But at greater depths the temperature rises, and from around 8,000 kilometres below the cloud cover, the electrical conductivity, thanks to the formation of plasma, is high enough for the dynamo to start.
“Crucial here is the product of wind speed and electrical conductivity,” explains Moritz Heimpel from the University of Alberta in Edmonton, Canada. As soon as it exceeds a specific value, a magnetic field can form. “The jet shears the magnetic field in the east-west direction and produces a characteristic magnetic band structure in the equatorial region,” says Thomas Gastine, a staff member at the Max Planck Institute for Solar System Research.
“In order to portray the special properties of the two dynamo processes involved, it was particularly important to model the interior properties of the planet as accurately as possible,” adds Lucia Duarte, who carried out the first computation during her doctoral work at the Max Planck Institute in Göttingen.
Hence, two magnetic fields form, which superimpose: the Earth-like one in the deep layer of the metal-like conducting hydrogen, and the weaker band structure generated by the equatorial jet. “The Earth-like field corresponds in strength and structure to the measurement data to date provided by space probes, which do not allow the band structure to be resolved,” says Thomas Gastine.
The simulations span a period of around 6,500 years and also reveal changes. The field strength should vary, for example, and the inclination of the axis should change by around 0.02 degrees per year. It will soon be possible for the Juno space probe to check this and further properties predicted by the new model.
The American space craft was launched three years ago and is due to enter into an orbit around the giant planet in August 2016. “With the new measurement data, we will find out much more about the inner structure and the magnetic field than has been possible to date, and can hopefully confirm the band structures as well,” says Johannes Wicht.
Wednesday 20 August 2014
Most Massive Known Galaxies Observed at Edge of the Universe (Today's Most Popular)
Four previously unknown galaxy clusters each potentially containing thousands of individual galaxies have been discovered some 10 billion light years from Earth. Most clusters in the universe today are dominated by giant elliptical galaxies in which the dust and gas has already been formed into stars. "What we believe we are seeing in these distant clusters are giant elliptical galaxies in the process of being formed," says David Clements, from the Department of Physics at Imperial College London.
An international team of astronomers, led by Imperial College London, used a new way of combining data from the two European Space Agency satellites, Planck and Herschel, to identify more distant galaxy clusters than has previously been possible. The researchers believe up to 2000 further clusters could be identified using this technique, helping to build a more detailed timeline of how clusters are formed.
Galaxy clusters are the most massive objects in the universe, containing hundreds to thousands of galaxies, bound together by gravity. While astronomers have identified many nearby clusters, they need to go further back in time to understand how these structures are formed. This means finding clusters at greater distances from the Earth.
The light from the most distant of the four new clusters identified by the team has taken over 10 billion years to reach us. This means the researchers are seeing what the cluster looked like when the universe was just three billion years old.
"Although we're able to see individual galaxies that go further back in time, up to now, the most distant clusters found by astronomers date back to when the universe was 4.5 billion years old," explains Clements. "This equates to around nine billion light years away. Our new approach has already found a cluster in existence much earlier than that, and we believe it has the potential to go even further."
The clusters can be identified at such distances because they contain galaxies in which huge amounts of dust and gas are being formed into stars. This process emits light that can be picked up by the satellite surveys.
Observations were recorded by the Spectral and Photometric Imaging Receiver (SPIRE) instrument as part of Herschel Multi-tiered Extragalactic Survey (HerMES). Seb Oliver, Head of the HerMES survey said: "The fantastic thing about Herschel-SPIRE is that we are able to scan very large areas of the sky with sufficient sensitivity and image sharpness that we can find these rare and exotic things. This result from Dr. Clements is exactly the kind of thing we were hoping to find with the HerMES survey"
The researchers are among the first to combine data from two satellites that ended their operations last year: the Planck satellite, which scanned the whole sky, and the Herschel satellite, which surveyed certain sections in greater detail.
The researchers used Planck data to find sources of far-infrared emission in areas covered by the Herschel satellite, then cross referenced with Herschel data to look at these sources more closely. Of sixteen sources identified by the researchers, most were confirmed as single, nearby galaxies that were already known. However, four were shown by Herschel to be formed of multiple, fainter sources, indicating previously unknown galaxy clusters.
The team then used additional existing data and new observations to estimate the distance of these clusters from Earth and to determine which of the galaxies within them were forming stars. The researchers are now looking to identify more galaxy clusters using this technique, with the aim of looking further back in time to the earliest stage of cluster formation.
NGC 7049 shown at the top of the page is a giant galaxy on the border between spiral and elliptical galaxies that spans about 150,000 light-years. It is located about 100 million light-years away from Earth in the southern constellation of Indus. NGC 7049 is the “brightest” galaxy of the Indus Triplet of galaxies (NGC 7029, NGC 7041, NGC 7049), and its structure might have arisen from several recent galaxy collisions.
Bright Cluster Galaxies are among the most massive galaxies in the universe and are also the oldest. They provide astronomers the opportunity of studying the many globular clusters contained within them. NGC 7049 has far fewer such clusters than other similar giant galaxies in very big, rich groups. This indicates to astronomers how the surrounding environment influenced the formation of galaxy halos in the early Universe.
The globular clusters in NGC 7049 are seen as the sprinkling of small faint points of light in the galaxy’s halo. The halo – the ghostly region of diffuse light surrounding the galaxy – is composed of myriads of individual stars and provides a luminous background to the remarkable swirling ring of dust lanes surrounding NGC 7049′s core.
NGC 7049′s striking appearance is primarily due to this unusually prominent dust ring, seen mostly in silhouette. The opaque ring is much darker than the millions of bright stars glowing behind it. Generally these dust lanes are seen in much younger galaxies with active star forming regions. Not visible in this image is an unusual central polar ring of gas circling out of the plane near the galaxy’s center.
The image was taken by the Advanced Camera for Surveys on the Hubble Space Telescope, which is optimised to hunt for galaxies and galaxy clusters in the remote and ancient Universe, at a time when our cosmos was very young.
The research involved scientists from the UK, Spain, USA, Canada, Italy and South Africa. It was published in the Monthly Notices of the Royal Astronomical Society and was part funded by the Science and Technology Facilities Research Council and the UK Space Agency.
Galaxy clusters are the most massive objects in the universe, containing hundreds to thousands of galaxies, bound together by gravity. While astronomers have identified many nearby clusters, they need to go further back in time to understand how these structures are formed. This means finding clusters at greater distances from the Earth.
The light from the most distant of the four new clusters identified by the team has taken over 10 billion years to reach us. This means the researchers are seeing what the cluster looked like when the universe was just three billion years old.
"Although we're able to see individual galaxies that go further back in time, up to now, the most distant clusters found by astronomers date back to when the universe was 4.5 billion years old," explains Clements. "This equates to around nine billion light years away. Our new approach has already found a cluster in existence much earlier than that, and we believe it has the potential to go even further."
The clusters can be identified at such distances because they contain galaxies in which huge amounts of dust and gas are being formed into stars. This process emits light that can be picked up by the satellite surveys.
Observations were recorded by the Spectral and Photometric Imaging Receiver (SPIRE) instrument as part of Herschel Multi-tiered Extragalactic Survey (HerMES). Seb Oliver, Head of the HerMES survey said: "The fantastic thing about Herschel-SPIRE is that we are able to scan very large areas of the sky with sufficient sensitivity and image sharpness that we can find these rare and exotic things. This result from Dr. Clements is exactly the kind of thing we were hoping to find with the HerMES survey"
The researchers are among the first to combine data from two satellites that ended their operations last year: the Planck satellite, which scanned the whole sky, and the Herschel satellite, which surveyed certain sections in greater detail.
The researchers used Planck data to find sources of far-infrared emission in areas covered by the Herschel satellite, then cross referenced with Herschel data to look at these sources more closely. Of sixteen sources identified by the researchers, most were confirmed as single, nearby galaxies that were already known. However, four were shown by Herschel to be formed of multiple, fainter sources, indicating previously unknown galaxy clusters.
The team then used additional existing data and new observations to estimate the distance of these clusters from Earth and to determine which of the galaxies within them were forming stars. The researchers are now looking to identify more galaxy clusters using this technique, with the aim of looking further back in time to the earliest stage of cluster formation.
NGC 7049 shown at the top of the page is a giant galaxy on the border between spiral and elliptical galaxies that spans about 150,000 light-years. It is located about 100 million light-years away from Earth in the southern constellation of Indus. NGC 7049 is the “brightest” galaxy of the Indus Triplet of galaxies (NGC 7029, NGC 7041, NGC 7049), and its structure might have arisen from several recent galaxy collisions.
Bright Cluster Galaxies are among the most massive galaxies in the universe and are also the oldest. They provide astronomers the opportunity of studying the many globular clusters contained within them. NGC 7049 has far fewer such clusters than other similar giant galaxies in very big, rich groups. This indicates to astronomers how the surrounding environment influenced the formation of galaxy halos in the early Universe.
The globular clusters in NGC 7049 are seen as the sprinkling of small faint points of light in the galaxy’s halo. The halo – the ghostly region of diffuse light surrounding the galaxy – is composed of myriads of individual stars and provides a luminous background to the remarkable swirling ring of dust lanes surrounding NGC 7049′s core.
NGC 7049′s striking appearance is primarily due to this unusually prominent dust ring, seen mostly in silhouette. The opaque ring is much darker than the millions of bright stars glowing behind it. Generally these dust lanes are seen in much younger galaxies with active star forming regions. Not visible in this image is an unusual central polar ring of gas circling out of the plane near the galaxy’s center.
The image was taken by the Advanced Camera for Surveys on the Hubble Space Telescope, which is optimised to hunt for galaxies and galaxy clusters in the remote and ancient Universe, at a time when our cosmos was very young.
The research involved scientists from the UK, Spain, USA, Canada, Italy and South Africa. It was published in the Monthly Notices of the Royal Astronomical Society and was part funded by the Science and Technology Facilities Research Council and the UK Space Agency.
Thursday 14 August 2014
Puzzling Age of a Milky Way Globular Cluster Solved
Hubble observations of IC 4499 have helped to pinpoint the cluster's age: observations of this cluster from the 1990s suggested a puzzlingly young age when compared to other globular clusters within the Milky Way. However, since those first estimates new Hubble data have been obtained and it has been found to be much more likely that IC 4499 is actually roughly the same age as other Milky Way clusters at approximately 12 billion years old.
It was long been believed that all the stars within a globular cluster form at the about same time, a property which can be used to determine the cluster's age. For more massive globulars however, detailed observations have shown that this is not entirely true — there is evidence that they instead consist of multiple populations of stars born at different times. One of the driving forces behind this behavior is thought to be gravity: more massive globulars manage to grab more gas and dust, which can then be transformed into new stars.
IC 4499 is a somewhat special case. Its mass lies somewhere between low-mass globulars, which show a single generation build-up, and the more complex and massive globulars which can contain more than one generation of stars. By studying objects like IC 4499 astronomers can therefore explore how mass affects a cluster's contents. Astronomers found no sign of multiple generations of stars in IC 4499 — supporting the idea that less massive clusters in general only consist of a single stellar generation.
IC 4499 is a somewhat special case. Its mass lies somewhere between low-mass globulars, which show a single generation build-up, and the more complex and massive globulars which can contain more than one generation of stars. By studying objects like IC 4499 astronomers can therefore explore how mass affects a cluster's contents. Astronomers found no sign of multiple generations of stars in IC 4499 — supporting the idea that less massive clusters in general only consist of a single stellar generation.
Wednesday 6 August 2014
World's 1st Robotic Laser Probes Kepler-Mission's Alien Star Systems
“We’re using Robo-AO’s extreme efficiency to survey in exquisite detail all of the candidate exoplanet host stars that have been discovered by NASA’s Kepler mission,” said Dr. Christoph Baranec of the University of Hawaii at Manoa’s Institute for Astronomy. “While Kepler has an unrivaled ability to discover exoplanets that pass between us and their host star, it comes at the price of reduced image quality, and that’s where Robo-AO excels.”
An international team led by Baranec is using the world’s first robotic laser adaptive optics system—Robo-AO— to explore thousands of exoplanet systems (planets around other stars) at resolutions approaching those of the Hubble Space Telescope. The results, which shed light on the formation of exotic exoplanet systems and confirm hundreds of exoplanets, have just been published in the Astrophysical Journal. The design and operation of the unprecedented instrument has just been published in the Astrophysical Journal Letters.
Laser adaptive optics systems are used by terrestrial telescopes to remove the image-blurring effects of Earth’s turbulent atmosphere, thereby capturing much sharper images than are otherwise possible from the ground. Baranec, Robo-AO’s principal investigator and lead author of the Astrophysical Journal Letter, led the development of the innovative Robo-AO system on the Palomar 1.5-meter telescope. It is the world’s first instrument that fully automates the complex and often inefficient operation of laser adaptive optics.
Analysis of the first part of the Robo-AO/Kepler exoplanet host survey is already yielding surprising results. “We’re finding that “hot Jupiters”—rare giant exoplanets in tight orbits—are almost three times more likely to be found in wide binary star systems than other exoplanets, shedding light on how these exotic objects formed,” said Nicholas Law (University of North Carolina at Chapel Hill’s College of Arts and Sciences), Robo-AO’s project scientist and lead author on the Astrophysical Journal paper.
The automated observations taken with Robo-AO, color coded by scientific project (current to March 25, 2014). The dense red cluster in the upper left is the Kepler field. Credit: Robo-AO Collaboration.
“Going further, Robo-AO’s unique capabilities have allowed us to discover even rarer objects: binary star systems where each star has a Kepler-detected planetary system of its own. These systems will be uniquely interesting for studies of how the planets formed—and for science fiction about what life would be like with another planetary system right next door,” continued Law.
Indeed, the first Robo-AO survey, covering 715 Kepler candidate exoplanet hosts, is the single largest scientific adaptive optics survey ever. That record won’t stand for very long, as the Robo-AO team is extending the survey to image each and every of the 4,000 Kepler candidate exoplanet hosts, and is ready to observe exoplanet hosts from Kepler’s new K2 mission as they are discovered.
The key to Robo-AO’s success is its efficiency, allowing it to observe hundreds more targets per night than conventional adaptive optics systems. So far, the Robo-AO system has already been used to make over 13,000 observations.
“The automation of laser adaptive optics has allowed us to tackle scientific questions that were unimaginable just a few years ago. We can now observe tens of thousands of objects at Hubble-Space-Telescope-like resolution in short periods of time,” Baranec said. “Now that the technology has been proven, we’re looking to bring it to the pristine skies of Maunakea, Hawaii, where it will be even more powerful.”
The Daily Galaxy via Astrobio.net and University of Hawaii
Image credit: The NASA artist's concept at top of the page depicts multiple-transiting planet systems, which are stars with more than one planet. The planets eclipse or transit their host star from the vantage point of the observer.
Laser adaptive optics systems are used by terrestrial telescopes to remove the image-blurring effects of Earth’s turbulent atmosphere, thereby capturing much sharper images than are otherwise possible from the ground. Baranec, Robo-AO’s principal investigator and lead author of the Astrophysical Journal Letter, led the development of the innovative Robo-AO system on the Palomar 1.5-meter telescope. It is the world’s first instrument that fully automates the complex and often inefficient operation of laser adaptive optics.
Analysis of the first part of the Robo-AO/Kepler exoplanet host survey is already yielding surprising results. “We’re finding that “hot Jupiters”—rare giant exoplanets in tight orbits—are almost three times more likely to be found in wide binary star systems than other exoplanets, shedding light on how these exotic objects formed,” said Nicholas Law (University of North Carolina at Chapel Hill’s College of Arts and Sciences), Robo-AO’s project scientist and lead author on the Astrophysical Journal paper.
The automated observations taken with Robo-AO, color coded by scientific project (current to March 25, 2014). The dense red cluster in the upper left is the Kepler field. Credit: Robo-AO Collaboration.
“Going further, Robo-AO’s unique capabilities have allowed us to discover even rarer objects: binary star systems where each star has a Kepler-detected planetary system of its own. These systems will be uniquely interesting for studies of how the planets formed—and for science fiction about what life would be like with another planetary system right next door,” continued Law.
Indeed, the first Robo-AO survey, covering 715 Kepler candidate exoplanet hosts, is the single largest scientific adaptive optics survey ever. That record won’t stand for very long, as the Robo-AO team is extending the survey to image each and every of the 4,000 Kepler candidate exoplanet hosts, and is ready to observe exoplanet hosts from Kepler’s new K2 mission as they are discovered.
The key to Robo-AO’s success is its efficiency, allowing it to observe hundreds more targets per night than conventional adaptive optics systems. So far, the Robo-AO system has already been used to make over 13,000 observations.
“The automation of laser adaptive optics has allowed us to tackle scientific questions that were unimaginable just a few years ago. We can now observe tens of thousands of objects at Hubble-Space-Telescope-like resolution in short periods of time,” Baranec said. “Now that the technology has been proven, we’re looking to bring it to the pristine skies of Maunakea, Hawaii, where it will be even more powerful.”
The Daily Galaxy via Astrobio.net and University of Hawaii
Image credit: The NASA artist's concept at top of the page depicts multiple-transiting planet systems, which are stars with more than one planet. The planets eclipse or transit their host star from the vantage point of the observer.
Monday 4 August 2014
Mars' Curiosity Reaches Mount Sharp Goal --Rising Three Miles Above Gale Crater Floor
"We're coming to our first taste of a geological unit that's part of the base of the mountain rather than the floor of the crater," said Curiosity Project Scientist John Grotzinger of the California Institute of Technology, Pasadena. "We will cross a major terrain boundary."
Curiosity landed inside Gale Crater on Aug. 5, 2012, PDT (Aug. 6, 2012, EDT). During its first year of operations, it fulfilled its major science goal of determining whether Mars ever offered environmental conditions favorable for microbial life. Clay-bearing sedimentary rocks on the crater floor in an area called Yellowknife Bay yielded evidence of a lakebed environment billions of years ago that offered fresh water, all of the key elemental ingredients for life, and a chemical source of energy for microbes, if any existed there.
As it approaches the second anniversary of its landing on Mars, NASA's Curiosity rover is also approaching its first close look at bedrock that is part of Mount Sharp, the layered mountain in the middle of Mars' Gale Crater.
The mission made important discoveries during its first year by finding evidence of ancient lake and river environments. During its second year, it has been driving toward long-term science destinations on lower slopes of Mount Sharp. Those destinations are in an area beginning about 2 miles (3 kilometers) southwest of the rover's current location, but an appetizer outcrop of a base layer of the mountain lies much closer -- less than one-third of a mile (500 meters) from Curiosity. The rover team is calling the outcrop "Pahrump Hills."
For about half of July, the rover team at NASA's Jet Propulsion Laboratory in Pasadena, California, drove Curiosity across an area of hazardously sharp rocks called "Zabriskie Plateau." Damage to Curiosity's aluminum wheels from driving across similar terrain last year prompted a change in route planning to skirt such rock-studded terrain wherever feasible. The one-eighth mile (200 meters) across Zabriski Plateau was one of the longest stretches without a suitable detour on the redesigned route toward the long-term science destination.
"The wheels took some damage getting across Zabriskie Plateau, but it's less than I expected from the amount of hard, sharp rocks embedded there," said JPL's Jim Erickson, project manager for Curiosity. "The rover drivers showed that they're up to the task of getting around the really bad rocks. There will still be rough patches ahead. We didn't imagine prior to landing that we would see this kind of challenge to the vehicle, but we're handling it."
Another recent challenge appeared last week in the form of unexpected behavior by an onboard computer currently serving as backup. Curiosity carries duplicate main computers. It has been operating on its B-side computer since a problem with the A-side computer prompted the team to command a side swap in February 2013. Work in subsequent weeks of 2013 restored availability of the A-side as a backup in case of B-side trouble. Last week, fresh commanding of the rover was suspended for two days while engineers confirmed that the A-side computer remains reliable as a backup.
NASA's Mars Science Laboratory Project continues to use Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions. The destinations on Mount Sharp offer a series of layers that recorded different chapters in the environmental evolution of early Mars.
As it approaches the second anniversary of its landing on Mars, NASA's Curiosity rover is also approaching its first close look at bedrock that is part of Mount Sharp, the layered mountain in the middle of Mars' Gale Crater.
The mission made important discoveries during its first year by finding evidence of ancient lake and river environments. During its second year, it has been driving toward long-term science destinations on lower slopes of Mount Sharp. Those destinations are in an area beginning about 2 miles (3 kilometers) southwest of the rover's current location, but an appetizer outcrop of a base layer of the mountain lies much closer -- less than one-third of a mile (500 meters) from Curiosity. The rover team is calling the outcrop "Pahrump Hills."
For about half of July, the rover team at NASA's Jet Propulsion Laboratory in Pasadena, California, drove Curiosity across an area of hazardously sharp rocks called "Zabriskie Plateau." Damage to Curiosity's aluminum wheels from driving across similar terrain last year prompted a change in route planning to skirt such rock-studded terrain wherever feasible. The one-eighth mile (200 meters) across Zabriski Plateau was one of the longest stretches without a suitable detour on the redesigned route toward the long-term science destination.
"The wheels took some damage getting across Zabriskie Plateau, but it's less than I expected from the amount of hard, sharp rocks embedded there," said JPL's Jim Erickson, project manager for Curiosity. "The rover drivers showed that they're up to the task of getting around the really bad rocks. There will still be rough patches ahead. We didn't imagine prior to landing that we would see this kind of challenge to the vehicle, but we're handling it."
Another recent challenge appeared last week in the form of unexpected behavior by an onboard computer currently serving as backup. Curiosity carries duplicate main computers. It has been operating on its B-side computer since a problem with the A-side computer prompted the team to command a side swap in February 2013. Work in subsequent weeks of 2013 restored availability of the A-side as a backup in case of B-side trouble. Last week, fresh commanding of the rover was suspended for two days while engineers confirmed that the A-side computer remains reliable as a backup.
NASA's Mars Science Laboratory Project continues to use Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions. The destinations on Mount Sharp offer a series of layers that recorded different chapters in the environmental evolution of early Mars.
Milky Way's Motion Syncs New Planck Space Telescope Discovery with Big Bang Theory
Last year, the Planck Telescope revealed the most detailed picture of the cosmic microwave background, the relic radiation from the Big Bang. But this map contains features that challenge the standard model of cosmology, the theory that describes our entire Universe from early on. Who is right, the map or the theory?
Our eyes see what is called visible light. But there is a lot of light that we can't see, like ultraviolet and microwave radiation. It turns out that a weak glow of microwave radiation fills the entire sky, in regions between stars. But where does this glow come from?
According to our current understanding of the Big Bang, this glow of microwave radiation is relic light emitted by the Universe when it was a mere 380 000 years old. Before that, the Universe was completely opaque, since light was trapped by a hot plasma. But as the Universe expanded and cooled, electrons and protons combined to form stable atoms, and light was free to propagate for the first time.
In principle, this first light has traveled through time and is reaching us now in the form of microwave radiation. Slight variations in this background radiation indicate the seeds of current structure in the Universe, from planets, solar systems, and galaxies all the way to clusters of galaxies, clusters of clusters.
The European Space Agency set out to map this radiation to unprecedented resolution by launching the Planck space telescope. Scientists collected information from the telescope and processed it to remove unwanted foreground light, like from stars and galaxies. The information was then assembled together to give the most detailed map of microwave radiation of cosmic origin – a microwave photograph of the early Universe.
While the map is generally in agreement with our current theory of the Big Bang, it also contains unexpected features at large-scales, called anomalies. For example, the famous "cold-spot". On Planck's map, this region of the universe is characterized by its unusually low temperature. It is just a matter of a few tens of millionths of a degree difference in temperature, which might seem negligible, but it is enough for the map to no longer entirely fit the theory.
Cosmologists are at odds over the source of these anomalies. Do these large-scale features reveal phenomena that require new physics? Or does the information gathered by the Planck space telescope need to be processed differently?
A recent European study led by EPFL cosmologist Anaïs Rassat indicates that several of the anomalies disappear if the data from the Planck satellite are processed in a new way. "Using new techniques to separate the foreground light from the background, and taking into account effects like the motion of our Galaxy, we found that most of the claimed anomalies we studied, like the cold spot, stop being problematic," explains Rassat.
Previous methods were left with some regions of unwanted light that needed to be masked in the analysis. Instead, Rassat and her partners from CEA in France, studied a map that avoided masking techniques altogether, giving access to the whole sky. Next, they corrected the data by taking into account the way our Galaxy moves. They also adjusted the data for distortions in the relic light itself as it traveled through moving charged particles in an expanding Universe as well as other known gravitational effects.
While Rassat and her collaborators have shown that several anomalies were no longer problematic, others may nevertheless persist in the data. For Rassat, this work is just a first step towards systematically going through all of the possible large-scale irregularities and trying to explain their origin. Until then, there is still room for new physics.
The findings of the scientists from EPFL (Switzerland) and CEA (France)are published in the August 4th, 2014 edition of the Journal of Cosmology and Astroparticle Physics.
According to our current understanding of the Big Bang, this glow of microwave radiation is relic light emitted by the Universe when it was a mere 380 000 years old. Before that, the Universe was completely opaque, since light was trapped by a hot plasma. But as the Universe expanded and cooled, electrons and protons combined to form stable atoms, and light was free to propagate for the first time.
In principle, this first light has traveled through time and is reaching us now in the form of microwave radiation. Slight variations in this background radiation indicate the seeds of current structure in the Universe, from planets, solar systems, and galaxies all the way to clusters of galaxies, clusters of clusters.
The European Space Agency set out to map this radiation to unprecedented resolution by launching the Planck space telescope. Scientists collected information from the telescope and processed it to remove unwanted foreground light, like from stars and galaxies. The information was then assembled together to give the most detailed map of microwave radiation of cosmic origin – a microwave photograph of the early Universe.
While the map is generally in agreement with our current theory of the Big Bang, it also contains unexpected features at large-scales, called anomalies. For example, the famous "cold-spot". On Planck's map, this region of the universe is characterized by its unusually low temperature. It is just a matter of a few tens of millionths of a degree difference in temperature, which might seem negligible, but it is enough for the map to no longer entirely fit the theory.
Cosmologists are at odds over the source of these anomalies. Do these large-scale features reveal phenomena that require new physics? Or does the information gathered by the Planck space telescope need to be processed differently?
A recent European study led by EPFL cosmologist Anaïs Rassat indicates that several of the anomalies disappear if the data from the Planck satellite are processed in a new way. "Using new techniques to separate the foreground light from the background, and taking into account effects like the motion of our Galaxy, we found that most of the claimed anomalies we studied, like the cold spot, stop being problematic," explains Rassat.
Previous methods were left with some regions of unwanted light that needed to be masked in the analysis. Instead, Rassat and her partners from CEA in France, studied a map that avoided masking techniques altogether, giving access to the whole sky. Next, they corrected the data by taking into account the way our Galaxy moves. They also adjusted the data for distortions in the relic light itself as it traveled through moving charged particles in an expanding Universe as well as other known gravitational effects.
While Rassat and her collaborators have shown that several anomalies were no longer problematic, others may nevertheless persist in the data. For Rassat, this work is just a first step towards systematically going through all of the possible large-scale irregularities and trying to explain their origin. Until then, there is still room for new physics.
The findings of the scientists from EPFL (Switzerland) and CEA (France)are published in the August 4th, 2014 edition of the Journal of Cosmology and Astroparticle Physics.
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