Tag Archives: dark energy

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Antimatter excess in space hints of tangible evidence of dark matter

A $1.6 billion cosmic ray experiment on the International Space Station has come across evidence of antimatter in space, a remarkable finding that was recently presented during a seminar at CERN and which might help probe the mysteries of dark matter – one of the major components that make up the Universe.

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The AMS-02 experiment is a state-of-the-art particle physics detector that is constructed, tested and operated by an international team composed of 56 institutes from 16 countries and organized under United States Department of Energy (DOE) sponsorship. Seen here as the round instrument labeled as “AMS”. (c) NASA

The find was made using the Alpha Magnetic Spectrometer (AMS), an instrument mounted on the International Space Station which has been likened by many as an LHC in space. AMS job is that of  surveying the sky for high-energy particles, or cosmic rays and has so far recorded 25 billion events. It’s main mission is that of identifying and describing dark matter, a mysterious component which we can not see, unlike regular matter, but which we know for sure exists because of the gravitational effects it holds on regular matter.

It’s believed that whenever dark matter collides, it forms antimatter as a result of what’s called annihilation. Antimatter is, naturally, the reverse of matter and every particle in the Universe has its corresponding antiparticle. For instance, the electron’s antiparticle is the antielectron, known as a positron. The electron and the antielectron have exactly the same masses, but they have exactly opposite electrical charges. Scientists believe that in the wake of the Big Bang an equal amount of matter and antimatter was ejected through out the Universe, however why they didn’t cancel each other out or why there seems to be more matter than anti-matter is a subject that’s giving physicists really big headaches.

Normal matter contributes just 4.9% of the mass/energy density of the Universe, dark matter is believed to range somewhere in the 26.8% margin, while dark energy – the force thought to be accelerating the expansion of the Universe – sits atop a comfortable majority of 68.3%.

Anyway, the AMS instrument shines by counting the numbers of electrons and their anti-matter counterparts from space – positrons – falling on an array of detectors. At the CERN seminar, completed just mere hours ago, AMS spokesperson and lead scientist Professor Samuel Ting unveiled some spectacular results. According to Ting, a slight excess of positrons in the positron-electron count was experienced, something expected in the aftermath of dark matter annihilation.

Evidence of dark matter finally found? Don’t get too excited…

This positron count excess could have come from pulsars, the spinning remnants of dead stars that throw off wild winds of radiation. Analysis has shown however that the positrons fall on the AMS from all directions, rather than a specific signal direction like one given off by a pulsar, suggesting what the researchers have come across are actually dark matter decay remnants. What this also suggests is that we may be on the brink of a monumental discovery in physics. According to the CERN press release:

“The AMS results are based on some 25 billion recorded events, including 400,000 positrons with energies between 0.5 GeV and 350 GeV, recorded over a year and a half. This represents the largest collection of antimatter particles recorded in space. The positron fraction increases from 10 GeV to 250 GeV, with the data showing the slope of the increase reducing by an order of magnitude over the range 20-250 GeV. The data also show no significant variation over time, or any preferred incoming direction. These results are consistent with the positrons originating from the annihilation of dark matter particles in space, but not yet sufficiently conclusive to rule out other explanations.”

CERN scientists, as they should be, are cautious and don’t mean to make bold statements as of yet.

“As the most precise measurement of the cosmic ray positron flux to date, these results show clearly the power and capabilities of the AMS detector,” said AMS spokesperson, Samuel Ting. “Over the coming months, AMS will be able to tell us conclusively whether these positrons are a signal for dark matter, or whether they have some other origin.”

If the more positrons than expected at higher energies can be attributed to dark matter remains to be seen, as we anxiously await new findings from AMS and CERN in the coming months. What’s certain is that only two years in its ten year mission, the AMS has already shown us a great deal, so expect much more from its behalf.

The findings are slated for publishing in the journal Physical Review Letters.

Cosmic microwave background seen by Planck

Map of the earliest recorded light paints broad picture of the ancient Universe

Cosmic microwave background seen by Planck

Cosmic microwave background seen by Planck. (c) ESA

Using the incredible  Planck cosmology probe astronomers at the European Space Agency have assembled a map of the “oldest light” in the sky – the cosmic microwave background (CMB) that was thrown into space in all directions just a few hundred thousand years after the Big Bang and which is still picked up here on Earth today.

What’s exciting about the map is that it confirms the current fundamental “cosmological inception” theory – the Big Bang theory. However there are some features and ideas that need to be refined and rethought as a result of the findings. For instance, according tot the new Planck all-sky map, the Universe is  13.82 billion years or 50 million years older than previous estimates. Also, there seems to be more matter (31.7%) and slightly less “dark energy” (68.3%) – the mysterious force that drives the Universe apart and causes an accelerated expansion.

The trace the map, cosmologists studied the CMB – light that was allowed to escape after the early Universe cooled down to allow the formation of hydrogen atoms some 380,000 years ago. By studying temperature fluctuations of the CMB –  seen as mottling in the map – scientists can better assess their current theoretical models with actual data on anomalies, since these fluctuations are thought to actually  reflect the differences in the density of matter when the light first escaped. These ripples are thought to have given rise to today’s vast cosmic web of galaxy clusters and dark matter.

anomaliesWhile some statistical analysis isn’t on par with data provided by the Planck map, cosmologists should rejoice as the news that their fundamental theories reflect reality. Especially those relating to the birth of the Universe, which is thought to have started as hot, dense state in an incredibly small space, and then expanded and cooled.

A cosmic baby picture

Other projects like the Cosmic Background Explorer and the Wilkinson Microwave Anisotropy Probe have provided earlier drafts of the “baby Universe”, however the map obtained from data gathered by the $900 million (€700 million) Planck probe launched in 2009 is the most detailed yet.

“The extraordinary quality of Planck’s portrait of the infant Universe allows us to peel back its layers to the very foundations, revealing that our blueprint of the cosmos is far from complete. Such discoveries were made possible by the unique technologies developed for that purpose by European industry,” says Jean-Jacques Dordain, ESA’s Director General.

“Since the release of Planck’s first all-sky image in 2010, we have been carefully extracting and analysing all of the foreground emissions that lie between us and the Universe’s first light, revealing the cosmic microwave background in the greatest detail yet,” adds George Efstathiou of the University of Cambridge, UK.

What also came as a surprise was a rather discrepant anomaly. Apparently, there’s an asymmetry in average temperature distribution across the Universe, as the southern sky hemisphere is slightly warmer than the north. Another significant anomaly is a cold spot in the map, centred on the constellation Eridanus, which is much bigger than would be predicted.

Nevertheless, cosmologists which have been dreaming about such a map for decades will now have their work cut out for them. Armed with this map, they now have the necessary resources or at least another tool at hand to prove or disprove some of the most controversial theories in cosmology today, like those discussing the rapid and far-reaching inflation of the Universe in its first moments from inception or the claim that there are six or seven spatial dimensions in addition to the three we perceive.

source: ESA

NASA teams up with ESA to discover dark matter

The American (NASA) and European (ESA) space agency have teamed up to create a new spacecraft that will hold a groundbreaking telescope. The mission, Euclid, will look at billions of galaxies, create a more accurate map of the Universe, and also map out the mysterious dark matter and dark energy.

Dark Matter and Dark Energy

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As much as these seem taken from sci-fi novels, they actually as true as it gets. The above chart paints quite a surprising picture; dark energy makes out almost three quarters of the universe! The hypothetical form of energy is thought to be the engine behind Universal expansion, but the very nature of it is a matter of debate. We have no direct information about it, only indirect observations from distance measurements and their relation to redshift; this is where it gets weird. It’s thought to be homogenous, not very dense, and (here’s the kicker) – doesn’t interact with any of the fundamental forces other than gravity. It has such a big effect on our Universe because it practically fills out the space that would otherwise be empty.

While dark energy has the size, dark matter has the weight. It’s estimated that dark matter accounts a large part of the total mass in the universe – 84% of the matter in the universe. The rest, that small percentage left – that’s us. Planets and stars and all that, yeah, that’s that small percentage.

Discovering the undiscoverable

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The existence of dark matter is only known because of the gravitational force it puts on other objects. Since it was first discovered in the 1930s, it remained one of the biggest mysteries out there, with no satisfactory explanation showing up. The Euclid mission hopes to reveal some insight into what makes up most of the universe; so far, mapping it and trying to find connections is the best we can do.

The Euclid mission will be launched in what is called the Sun-Earth Lagrange point 2; the Lagrange point is a gravitational stable point where the Earth’s and Sun’s gravity cancel each other out, or where their cummulative attraction keep a much smaller object stable. From there, it will spend six years mapping and studying up to 2 billion galaxies throughout the universe. Astrophysicists hope that, aside from any information on dark matter and dark energy, the euclid mission will also shed some light on how some galaxies formed.

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Physicists create negative temperature state – thermodynamic laws still stand

Well, the year really kicked off in style. This research is really next level physics, and in order to understand it (even slightly), we’re going to delve into some serious physics.

Dancing around absolute zero

quantum gas 0Over the years, physicists have made significant progress in cooling objects closer to absolute zero (0 Kelvin, the temperature at which all molecular motion stops because there is no energy in the classical sense. Absolute zero is the absolute zero, and you can’t reach it, so ultimately, you are limited. So how can you go below 0 Kelvin?

First of all, you have to understand that thermodynamics doesn’t define temperature as a physical parameter, but rather as a statistic of the energy distribution present so basically, you can create crazy temperatures with unusual distributions. Therefore, it is theoretically possible to have a negative value – just note that for this particular case, as weird as it would seem, negative doesn’t mean lower than zero. So how did they do it?

Well, you first want to bring the gas to almost zero temperature;  two concepts appear here: laser trapping and evaporative cooling. Basically, you have a flow of atoms running around in one direction. You point a laser exactly at them, in the opposite direction. Just like you would try running against a stream or a very powerful wind, the atoms are slowed down, stopped, or even pushed backwards. Then you put another laser in their original flow direction to even it out, and they are practically stuck. Do the same thing from up and down lasers, and you’ve trapped the atoms which are now stuck in your trap. That’s when evaporative cooling kicks in. Now remember, the temperature of the atoms is dependant strictly on their energy, so if we could somehow remove the high-state energy atoms, then we would be left only with the lower energy ones – the temperature would drop, and so would the temperature. To do this, researchers loosen the trap just a tiny bit – that way, the higher energy atoms can escape. Rinse and repeat, loosening it more and more, until you are stuck with only the low energy atoms and the low temperature. The thing is, even an extremely low amount of energy is some energy, so you can’t really do it until you reach 0 K(elvin). This is what researchers typically use when they want to drop temperatures close to 0, but in order to go negative, you have to use something different.

The physics

In a negative temperature system, temperatures get lower as more atoms pile up close to its maximum energy.

In a negative temperature system, temperatures get lower as more atoms pile up close to its maximum energy.

Again, many sites and magazines, even high quality ones are dancing around the issue here, so I’d like to underline it again: having negative temperatures on the Kelvin scale and going below absolute zero are not the same thing. In fact, they are fundamentally different.

Ulrich Schneider, a physicist at the Ludwig Maximilian University in Munich, Germany reached such sub-zero temperatures; after bringing them to extremely low temperatures, they used an ultracold quantum gas made up of potassium atoms, using lasers and magnetic fields to keep the individual atoms in a lattice arrangement. At positive temperatures, the atoms repel, making the configuration stable. The team then quickly adjusted the magnetic fields, causing the atoms to attract rather than repel each other – causing a major shift in the atoms.

“This suddenly shifts the atoms from their most stable, lowest-energy state to the highest possible energy state, before they can react,” says Schneider. “It’s like walking through a valley, then instantly finding yourself on the mountain peak.”

Wait, what? Here’s a relatively layman explanatiopn that I hope will clarify things. For a typical material with positive temperature, adding energy in the form of heat makes it more disordered, incerasing its entropy. Entropy can be loosely defined as a measure of the chaos in the system, so imagine this system. Say you have a system with equally equivalent atoms, all of which are in a low energy state (pretty much all systems have most atoms in low energy states). The system is perfectly ordered. Now, say you give the system just enough energy to lift one atom to a superior energy state; the entropy has increased – you have no way of telling which atom will rise, and the system suddenly becomes more chaotic, disordered. But say you somehow manage to create a system where all atoms but one are in a high energy state; when you add the same amount of energy, your system will become more ordered, as you know exactly which atom will rise, and you’ll again have a perfectly ordered system. That’s the thing here; if you give energy to a system it will become more and more disordered, up until a point where giving it energy will actually make it more ordered.

The team’s result marks the transition from just above absolute zero to a few billionths of a Kelvin below absolute zero.

Peculiarities

The whole idea is counter intuitive and requiers a firm understanding of thermodynamic principles to grasp, so it’s a little quirky to talk about what’s peculiar here, but what is just down right strange is that sub zero gases mimic ‘dark energy‘ – the mysterious form of energy which pushes and expands our Universe faster and faster, against the Universe’s own gravity.

“It’s interesting that this weird feature pops up in the Universe and also in the lab,” Schneider says. “This may be something that cosmologists should look at more closely.”

Galaxy clusters Abell 399 (lower centre) and Abell 401 (top left). The galaxy pair is located about a billion light-years from Earth, and the gas bridge extends approximately 10 million light-years between them. (c) ESA

Superhot filaments of gas connect galaxy clusters

Galaxy clusters Abell 399 (lower centre) and Abell 401 (top left). The galaxy pair is located about a billion light-years from Earth, and the gas bridge extends approximately 10 million light-years between them. (c) ESA

Galaxy clusters Abell 399 (lower centre) and Abell 401 (top left). The galaxy pair is located about a billion light-years from Earth, and the gas bridge extends approximately 10 million light-years between them. (c) ESA

Astronomers have for the  first time confirmed a bridge of hot gas with a temperature of about 80 million degrees Kelvin connecting a pair of galaxy clusters 10 million light-years apart. The discovery is of particular importance since it might help shed light on the missing baryonic matter that has been puzzling scientists for decades.

The two galaxy clusters, Abell 399 and Abell 401, each contain hundreds of galaxies and are several billion light years away from Earth. In the early universe, filaments of gaseous matter pervaded the cosmos in a giant web, with clusters eventually forming in the densest nodes, according to the leading theory on the matter – this is called the warm-hot intergalactic medium (WHIM).

Despite the fact that we’ve yet to see any actual evidence or manage to pinpoint what exactly these are, the Universe is dominated by what’s ambiguously called dark matter and dark energy. What we can actually measure and see – stars, galaxies, cosmic clouds of dust and gas, and so on – only make up a tiny fraction of the Universe, less than 5%. This ‘white’ matter is commonly referred to among astronomers as baryonic matter.

Now, this baryonic matter can be generally detected by measuring the electromagnetic radiation it releases. When observing distant cosmic objects like far away galaxies and stars, however, the baryonic matter readings do not match those from nearby – there’s a mismatch between matter in the ancient Universe and the close Universe. About half of the  baryonic matter expected to be present in the local Universe is missing. So where is it?

Well, many scientists believe it lies in this warm-hot intergalactic medium or WHIM that I mentioned earlier. Cosmic simulations have revealed that both dark and baryonic matter are embedded in  a filamentary network, and that the WHIM might account for most of the baryonic matter in the local Universe. This network of tenuous gas ranges in temperature from 100,000 to several tens of millions of K and due to its extremely low density has proved very hard to detect.

Hot gas bridging galaxy clusters

This latest findings based on microwave and sub-millimetre wavelength observation using  ESA’s Planck satellite has brought new light into these theories.

“Although the WHIM is mainly organised in long and diffuse filaments, we expect to find it also in the proximity to galaxy clusters, which are the largest gravitationally-bound structures in the Universe,” explains José M. Diego, a Planck Collaboration scientist from the Instituto de Fisica de Cantabria (UC-CSIC) in Santander, Spain.

“Planck can detect galaxy clusters across the sky because the hot gas that fills them imprints a characteristic signature on the Cosmic Microwave Background known as the Sunyaev-Zel’dovich effect,” Diego adds. “Based on the same principle, Planck could be sensitive to gas from the WHIM, too”.

In other words, this Sunyaev-Zel’dovich or S-Z effect describes a phenomenon in which cosmic microwave background light interacts with the hot gas permeating these huge cosmic structures, which leads to energy distribution being modified in a characteristic manner.

“Detecting the WHIM via the Sunyaev-Zel’dovich effect is extremely challenging due to its low density,” comments Juan Macias-Perez, a Planck Collaboration scientist from the Laboratoire de Physique Subatomique et de Cosmologie in Grenoble, France. “The best chance to detect it is to look at the regions between pairs of nearby galaxy clusters that are interacting with one another: as they approach each other, gas in the inter-cluster region becomes denser and hotter, hence easier for us to spot,” he adds.

So the scientists looked at data collected by the Planck surveys, and looked for clusters that satisfy a somewhat delicate condition – close enough for intervening filaments to be detected, but also separate enough for Planck to be able to resolve as individual sources. Picky, picky, but they hit the jackpot eventually.

“A careful analysis revealed a ‘bridge’ of hot gas connecting two of the clusters in the sample: Abell 399 and Abell 401,” comments Diego.

By combining Planck data with archival X-ray observations from the German satellite Rosat, the astronomers found that the temperature of the gad bridge between the two galaxy clusters was roughly 80 million degrees Kelvin.

Early analysis suggests that it could be a mixture of the elusive filaments of the cosmic web mixed with gas originating from the clusters, but more data is needed for a through conclusion to be made. Next, the scientists are keen on studying another promising galaxy cluster pair – the composite system Abell 3391-Abell 3395, which is highly substructured and may in fact consist of three or four clusters.

“This discovery highlights the ability of Planck to probe galaxy clusters out to their outskirts and even beyond, allowing us to investigate the connection between intra-cluster gas and gas that is part of the cosmic web,” concludes Jan Tauber, Planck project scientist at ESA.

Findings were published in the journal Astronomy & Astrophysics.

source: ESA

Universe Expansion Dark Energy

Dark energy influence on the Universe like a roller coster ride

Universe Expansion Dark Energy

(c) NASA

Scientists with the  Sloan Digital Sky Survey (SDSS-II) have used a novel technique to peer through the nature of dark energy as far as ten billion years ago and measure the  three-dimensional structure of the distant Universe. Tracing this 3-D map scientists were able to assess the influence of dark energy over time, which might help unravel the mysteries of this repulsive force.

For the past five billion years, the Universe expansion rate has been speeding up, a phenomenon attributed to dark energy by astronomers. In the early phase of the Universe, however, a few billion years after the Big Bang, this mysterious force did not have a dominant role as  gravity actually held sway, decelerating cosmic expansion.

“We know very little about dark energy but one of our ideas is that it is a property of space itself – when you have more space, you have more energy,” explained Dr Matthew Pieri, a BOSS team-member.

“So, dark energy is something that increases with time. As the Universe expands, it gives us more space and therefore more energy, and at some point dark energy takes over from gravity to end the deceleration and drive an acceleration,” the Portsmouth University, UK, researcher said.

The new measurement is based on data from the Baryon Oscillation Spectroscopic Survey (BOSS), one of the four surveys that make up SDSS-III, gathered using a novel technique called  “baryon acoustic oscillations” (BAO).  This technique uses small variations in matter left over from the early Universe as a “standard ruler” to compare the size of the Universe at various points in its history.

In order for this technique to work, scientists had to study very distant objects. However, very distant objects, like ancient, far away galaxies are faint and difficult to survey, so the astronomers decided to look after quasars, one of the most energetic objects in the Universe, to map the spread of hydrogen gas clouds in space.

Before the quasars’ electromagnetic radiation emissions reach Earth, they encounter clouds of hydrogen. Part of the light becomes thus absorbed, and the pattern of absorption betrays how the density of gas varies with distance along the line of sight to the telescope.

Measuring this absorption – a phenomenon known as the Lyman-alpha Forest – yields a detailed picture of the gas between us and the quasar.

“It’s a cool technique, because we’re essentially measuring the shadows cast by gas along a single line billions of light-years long,” says Anze Slosar of Brookhaven National Laboratory.

“The tricky part is combining all those one-dimensional maps into a three-dimensional map. It’s like trying to see a picture that’s been painted on the quills of a porcupine.”

Last year, the team of astronomers used data from 10,000 quasars gathered by the SDSS-III’s Baryon Oscillation Spectroscopic Survey (BOSS) to make the first large-scale map of the structure of the faraway “Lyman-alpha forest” gas. However, the resolution wasn’t high enough to detect the subtle variation of baryon acoustic oscillations. Now in their latest survey, the scientists build a map of 50,000 quasars that shows the distribution of hydrogen gas clouds reaching 11 billion light-years away  – just two billion years after the Big Bang itself.

Universe expansion is like a roller coaster ride

“If we think of the Universe as a roller coaster, then today we are rushing downhill, gaining speed as we go,” says Nicolas Busca of the Laboratoire Astroparticule et Cosmologie of the French Centre National de la Recherche Scientifique (CNRS), one of the lead authors of the study.

“Our new measurement tells us about the time when the Universe was climbing the hill – still being slowed by gravity.”

Equipped with this high detail map of BAOs, the scientists were able to paint a picture of how the Universe evolved through out history. For the first time, we see how dark energy worked at a time before the Universe’s current acceleration started.

The BOSS findings show that the expansion of the Universe slowed down some 11 billion years ago as a tug of war ensued  between the attractive gravitational forces of galaxies. As the Universe continued to expand,  the constant repulsive force of dark energy began to dominate as matter was diluted by the expansion of space. This is consistent with current Universe expansion theories.

“No technique has ever been able to probe this ancient era before,” says BOSS principal investigator David Schlegel of the Lawrence Berkeley National Laboratory.

“Back then, the expansion of the Universe was slowing down; today, it’s speeding up. How dark energy caused the transition from deceleration to acceleration is one of the most challenging questions in cosmology.

More than eighty years since Edwin Hubble and Georges Lemaitre first measured the expansion rate of the nearby Universe, the SDSS-III has made the same measurement of the expansion rate of the Universe 11 billion years ago. Currently, the BOSS project is only completed by a third. In the few years, scientists plan to map the locations of a million-and-a-half galaxies and more than 160,000 quasars. By the time SDSS-III is complete, it will have helped transform the Lyman-alpha forest technique from a risky idea into a standard method by which astronomers explore the nature of the faraway Universe, the authors involved in the study claim .

Findings were published in the journal Astronomy and Astrophysics.

New Experiment on to Revalidate Nobel Winning Universe Acceleration Finding

This year’s Nobel Prize winning finding that the ‘Universe is accelerating’ is being subjected to another validation test in the USA to confirm whether the expansion is “even or uneven”.

 

“We are testing the acceleration theory through another experiment to find whether the expansion is even or multi-directional. We are confident it would be ‘even’,” says eminent cosmologist Prof.Robert Kirshner who guided two of the three-member team of researchers that bagged the Nobel Prize in Physics – 2011 for the revolutionary finding recently.

With the experimental study now on, this time using the MMT telescope in Arizona and the Magellan Telescope in Northern Chile, he said, the researchers would, within two years, be in a position to collect enough data to determine whether the expansion of the Universe is even or in all directions, Kirshner said.

Kirshner of the Centre for Astrophysics, Harvard University (USA) was interacting with this Indian Science Writers Association(ISWA) representative in South Goa on the sidelines of the just concluded week-long VII International Conference on “Gravitation and Cosmology” organised by the International Centre for  Theoretical Sciences(ICTS) under the prestigious Tata Institute of Fundamental Research, Mumbai.

As many as 300 astrophysicists from across the world had participated in the conference and shared their findings and experiences on black holes,gravitation wave experiments and need for international collaborations to promote research in astrophysics of the 21st century.

His researchers – Adam Riess and Brian Schmidt – along with Perl mutter, had recently received the Nobel Prize in Physics for their stellar discovery in 1998, used the Panstars Telescope with big array of detectors with a gigapixel resolution to capture the image of many galaxies at the same time for the study.

“I am also confident that such high resolution and higher sensitive telescopes enable us trace the history of their shifts by recognizing what is known as their “Red Shifts” as the galaxies move away from us,” he said.

The on-going studies may also throw light on the ‘fossils of light” emitted when stars exploded during what is known as the “Big Bang” 14 billion years ago that led to the creation of the Universe.

“We expect data we gather could unlock the secrets of the origin of the Universe including the history of the first galaxies, stars and the supernovae and their death,” he said.

Scientists believe that the Universe contain galaxies, each composed of about 100 billion stars observable enough and 100 billion unobservable galaxies.

Earlier in his plenary talk in the conference on “Exploding Stars and the Accelerating Universe,” Kirshner said observations of exploding stars halfway across the universe show that the expansion of the universe is speeding up.

“We attribute this to a pervasive ‘dark energy’ whose properties we would like to understand. This work was recently honoured by the 2011 Nobel Prize in Physics to Perl Mutter, Schmidt and Riess.”

He had also presented the most recent evidence from supernovae, Cosmic Microwave Background (CMB) fluctuations, and galaxy clustering. The present state of knowledge on dark energy is completely consistent with a modern version of the cosmological constant, but with a ridiculously low value.

He also discussed ways to use infrared observations to make the supernova measurements with better accuracy and higher precision.

Kirshner also explained how improved supernova measurements and the matrix of evidence from other observations can help us understand whether modifications to general relativity or a time-varying component of dark energy can be ruled out.//EOM//

 

Astrophysicists create giant map of dark matter

Dark matter is a type of matter which astrophysicists believe covers the greater part of the Universe’s mass. However, dark matter can’t be seen, nor does it interract with any type of electromagnetic radiation – it is only observed through the gravitational object it has on other bodies. Dark matter is estimated to constitute 84% of the matter in the universe and 23% of the mass-energy. Now, astrophysicists have mapped the first 3D image of a gigantic dark matter filament.

By studying and collating images from the Hubble Space Telescope, researchers were able to get a pretty accurate picture of dark matter (shown in blue in the above picture) – extending some 60 million light years away from a massive galactic cluster called MACS J0717.

Current theories suggest than then the Big Bang took placedense matter condensed into a web of tangled dark matter filaments throughout the universe, a process they’ve mapped in computer simulations. It is believed that dark matter is structured like a angled web, with long strings of mostly dark matter intersecting at giant galaxy clusters. But identifying these filaments in outer space – that’s an entirely different thing.

“Filaments of the cosmic web are hugely extended and very diffuse, which makes them extremely difficult to detect, let alone study in 3D,” said the study’s lead author, Mathilde Jauzac of LAM in France and University of KwaZulu-Natal in South Africa.

The cluster itself was important for the study.

“From our earlier work on MACS J0717, we knew that this cluster is actively growing, and thus a prime target for a detailed study of the cosmic web,” study researcher Harald Ebeling, of the University of Hawaii at Manoa, said in a statement Tuesday (Oct. 16).

The length of the filament (60 million light years) is absolutely huge, and the fact that researchers were able to map it 3D makes the achievement even more significant. Also, if this string is representative for others in terms of size, then these strings might contain even more dark matter than theorists had predicted.

The study will be published in the Nov. 1 issue of Monthly Notices of the Royal Astronomical Society.

The first images from the world’s most powerful camera [STUNNING PHOTOS]

The Dark Energy Camera (DECam) is the most powerful sky survey instrument yet built, a collaborative international effort which took more than eight hard years worth of planning and design. Recently, the camera, installed on top of a mountain in Chile at the Victor Blanco Telescope at the Cerro Tololo Inter-American Observatory, was tested for the first time and came back with some incredible sights.

So far, two images have been released to the public, both taken just a few days ago on September 12. The first one, from above is the stunning  globular star cluster 47 Tucanae, a mere 17,000 light years away. Below is the barred spiral galaxy NGC 1365, in the Fornax cluster of galaxies, which lies a whooping 60 million light years from Earth.

The DECam, which is photometric imaging camera, was developed by the Dark Energy Survey (DES) collaboration based at the Fermi National Accelerator Laboratory. The instrument works by measuring the amount of light emitted by cosmic objects, rather than spectral details. Consisting of  62 charge-coupled devices (CCDs), which allow for capturing 570 megapixels images, the camera is capable of imaging galaxies up to 8 billion light years away.

Currently, DECAM’s goal is to measure the expansion history of the universe by collecting images of 4,000 distant supernovae and 300 million distant galaxies within the next five years and plotting the largest 3-D map of the Universe. The current largest 3-D map of the Universe has been released by the third Sloan Digital Sky Survey and its largest component, the Baryon Oscillation Spectroscopic Survey (BOSS).

via Gizmodo

The 2.5m Sloan telescope at Apache Point Observatory. (c) SDSS

Survey reveals how dark energy expanded and shaped the Universe

The 2.5m Sloan telescope at Apache Point Observatory. (c) SDSS

The 2.5m Sloan telescope at Apache Point Observatory. (c) SDSS

Encompassing years worth of work, the  Sloan Digital Sky Survey (SDSS-III) has now precisely measured the distance between over a quarter of a million galaxies. As part of the project, called the Baryon Oscillation Spectroscopic Survey, or BOSS, scientists built a massive map of all the studied galaxies so far, some more than six billion years ago – a period that marks a tipping point in the Universe’s history. Around this time, matter became so spread out that gravity wasn’t enough to slow down the Universe’s attraction, and instead dark energy took over causing the Universe to begin an accelerated expansion process which continues to this day. Dark energy is still a huge mystery even to the most enlightened astrophysicists, however what makes the  Baryon Oscillation Spectroscopic Survey extremely exciting so far is that it confirms the theoretical models proposed.

Scientists claim that dark energy accounts for 73% of all the mass-energy in the universe. That’s a massive proportion, considering that dark energy is still just that thing, expressed in cosmological constants in mathematical models. Understanding dark energy, thus, becomes a key prerequisite to holistically understanding the Universe.

“There’s been a lot of talk about using galaxy maps to find out what’s causing accelerating expansion,” says David Schlegel of the Lawrence Berkeley National Laboratory.

“We’ve been making a map, and now we’re using it – starting to push our knowledge out to the distances when dark energy turned on.

The BOSS project was centered around the fascinating  baryon acoustic oscillations. These sound waves were emitted some 30,000 years after the Big Bang and then continued to oscillated throughout for some 350,000 years, when the Universe cooled down and hampered their propagation. Matter clustered around the center and edges of the wave, basically guiding galaxies to form in those areas.

The Sloan Digital Sky Survey found that these galaxies were found to be almost at the exact location predicted by the model, helping scientists measure how fast the Universe was expanding six billion years ago, to an accuracy of two percent.

Besides providing highly accurate measurements of the distances between galaxies, the BOSS also serves as a great experiment for testing Einstein’s Theory of Relativity.

“Since gravity attracts, galaxies at the edges of galaxy clusters fall in toward the centres of the clusters,” says Beth Reid, a NASA Hubble Fellow at Lawrence Berkeley National Laboratory.

“General Relativity predicts just how fast they should be falling. If our understanding of General Relativity is incomplete, we should be able to tell from the shapes we see in BOSS’s maps near known galaxy clusters.”

The rate at which galaxies fall into clusters, however, is well consistent with Einstein’s predictions, thus providing another sound proof debunking General Relativity naysayers.

“We already knew that the predictions of General Relativity are extremely accurate for distances within the solar system,” says Reid, “and now we can say that they are accurate for distances of 100 million light-years.

We’re looking a billion times further away than Einstein looked when he tested his theory, but it still seems to work.”

The survey is still a long way from being finished, as only a third of it was completed thus far. As scientists map the Universe at an even greater scale and dwell deeper, billions of light years farther, the Universe’s secrets will come closer to becoming unraveled.

The findings were published in the journal Cosmology and Extragalactic Astrophysics.

[via io9]

‘El Gordo’ – largest galaxy cluster ever seen, is colliding and growing

Galaxy clusters are the biggest stable structures in our Universe that we know of, typically containing 50 to 1000 galaxies.

El Gordo

Seven billion light years away and two million billion times heavier than our Sun lies El Gordo – which is Spanish for ‘the fat one’. Astronomers reporting at the 219th American Astronomical Society meeting said that at the moment, El Gordo is undergoing a process of growth and collision, and that it will grow even larger.

Aside from discovering it, which is really remarkable in itself, astrophysicists have set out to figure exactly how these clusters form, collide and grow – and they hope El Gordo can play a big role here.

“El Gordo is at a distance that corresponds to a distance of about seven billion light years – we’re looking at it at a time that the Universe was only half as old as it is now, when structure was forming at a different rate,” explained Jack Hughes of Rutgers University in New Jersey, US.

Stellar superlatives

Galaxy clusters hold many records, and from what we know so far, collisions like the ones in El Gordo are the most energetic events in the Universe, as incredible amounts of matter and dark matter collide at incredible speeds. Just imagine a collision between hundreds and hundreds of galaxies, all of them filled with stars and planets and dark matter, just colliding! Don’t know about you, but I find it really hard to wrap my mind around that.

Generally speaking, galaxy clusters grow by sheer force of gravity; they’re big, they’re heavy and they attract other objects – normal matter and dark matter work together here. But meanwhile, the much more mysterious dark energy works to pull the entire Universe apart at growing speeds. Understanding these connected processes is a Herculean task, and placing major galaxy clusters in this context is very important.

Big clusters, like El Gordo release energetic particles which affect the cosmic microwave background, the really faint background radiation left over from the Big Bang.

“By looking at and understanding the properties of El Gordo, we’re able to understand the time evolution of the structure formation of the Universe,” Prof Hughes said.

Right now, researchers are working on a model to show just how big the galaxy cluster will become.

El Gordo is going to continue to grow,” Prof Hughes said. “We could extrapolate what its mass will be; unfortunately the models are uncertain, but it could become the most massive cluster known about, even when we count the nearby Universe.”

Europe to lead ambitious Sun mission

Europe aims for the stars: known as the Solar Orbiter will fly towards the Sun and get closer to it than any other man made object has; also, ESA will launch two other missions with the purpose of studying dark matter and dark energy.

Closer to the Sun

The mission was adopted today, and it will cost almost one billion euro. NASA will also participate in the mission, providing two instruments for the probe and the rocket which will launch it on its way, but this very ambitious mission is Europe’s project – and everybody from the ESA seems very proud:

“And I’m really looking forward to Solar Orbiter, which will become the reference for solar physics in the years to come,” said Alvaro Gimenez, ESA’s director of science.

A launch date hasn’t been officially proposed yet, but somewhere around 2017-2019 seems quite likely, if anything doesn’t change significantly. The probe will orbit around the star, staring directly into the furnace; but staring isn’t its primary job.

“Solar Orbiter is not so much about taking high-resolution pictures of the Sun, although we’ll get those; it’s about getting close and joining up what happens on the Sun with what happens in space,” explained Tim Horbury from Imperial College London and one of Solar Orbiter’s lead scientists.

There are some phenomena around the sun which we have only a basic understanding of.

“The solar wind and coronal mass ejections – these big releases of material coming off the Sun; we don’t know precisely where they’re coming from, and precisely how they’re generated. Solar Orbiter can help us understand that.”

Dark energy and dark matter

The ESA delegates, who were meeting in Paris, also approved a mission to investigate two of the great mysteries of modern cosmology – dark matter and dark energy. Some physicists are convinced that these phenomena dictate and shape the way our Universe evolves. The Euclid telescope will map the distribution of galaxies to try to get some fresh insight on these dark puzzles.

Just like the solar orbiter, the Euclid telescope will cost around 1 billion euro, but it still needs to pass some legislative hurdles in order to be approver, so a launch will probably not occur until 2019.

“They are both exciting missions, and it was really good to hear today that the physics Nobel Prize was awarded to research on the accelerating Universe, which is of course linked to Euclid,” mister Himenez added.

Euclid has the Herculean task of mapping out the spread of galaxies and clusters of galaxies over 10 billion years of cosmic history, as well as mapping their 3D distributon. The patterns of huge voids that exist between galaxies can offer important clues about the expansion of the cosmos through time – expansion which appears to be accelerating as a consequence of some unknown property of space itself referred to by scientists as dark energy.

“Euclid will give us an insight into how structures in the Universe are growing and whether they are growing at the rate we expect from General Relativity (our theory of gravity on large scales),” said Bob Nichol, a Euclid scientist from Portsmouth University.

But there’s even more.

“But aside from all that, Euclid should also deliver a picture of the Universe that has Hubble clarity over the whole sky. Euclid will detect billions of objects and they will all be there for us to go look at. And when we look back 50 years from now, that could be the one thing about Euclid we all say was worth it – a tremendous legacy for our children,” he told BBC News.

NASA passing the torch

The European Space Agency wants to launch this project on its own, but that could change pretty quick, as the Americans are desperate to run a similar mission they call WFirst (Wide-Field Infrared Survey Telescope); however, due to the huge budget costs NASA underwent, it is likely that it won’t even be approved until Europe’s one has launched already – thus giving Europe a huge advantage in one of the most important fields of modern astrophysics. Thus, ESA has offered to give NASA a 20% part in this affair.

“The door is always open to the Americans, and we are ready to co-operate with them if they come with a reasonable proposal,” said Dr Gimenez.

All in all, ESA seems to be moving, slowly but certainly in the right direction, and in the decades to come, it’s quite possible for it to become the leading edge in space exploration and astrophysics.

Via BBC

Supercomputer simulation confirms Universe formation model

Astronomers at  UC Santa Cruz have set  a new benchmark for cosmological research for decades to come maybe, after successfully simulating the forming of distant galaxies, like our very own Milky Way, under the mysterious forces of dark matter and dark energy.

Named Bolshoi – for the Russian word meaning “grand” or “great” – the simulation’s results are on par with what astrophysicists have theorized for years, confirming the current models which try to explain how the “Big Bang” sparked the origin of the subatomic particles and galaxies that populate our expanding Universe. This extraordinary feat was reached after more than four years of hard work and with the help of the invaluable Pleiades supercomputer at NASA‘s Ames Research Center in Mountain View – one of the most powerful computing unit in the world.

“In one sense, you might think the initial results are a little boring, because they basically show that our standard cosmological model works,” physics Professor Joel Primack said in a university release Thursday. “What’s exciting is that we now have this highly accurate simulation that will provide the basis for lots of important new studies in the months and years to come.”

Anatoly Klypin, an astronomer at New Mexico State University, wrote the computer code that produced it, Primack said. He went on to say, the simulation will provide astronomers around the world with new guides for observing and describing the most distant galaxies that telescopes can see.

The simulation is based  on a “map” of the early universe that was created nearly 10 years ago by a satellite called the Wilkinson Microwave Anisotropy Probe, or Wmap. The afformentioned probe captured a faint microwave echoed by the long forgoten Big Bang, now calculated to have occurred 13.7 billion years ago, and has since then provided invaluable data for various models, simulations or Universe maps.

The simulation traces the evolution of large-scale structures in the universe, and reveals how “halos” of dark matter, still covered in mystery to scientists,  surround all the known galaxies to provide them with the gravity that holds them together.

“We know that the dark matter exists, but we still don’t know exactly what it is, yet it’s essential to explain the evolution and structure of all the stars and all the galaxies,” Primack said in an interview.

Dark matter – everywhere

Astronomers have calculated that dark matter accounts for something between 75 and 82 percent of all the matter in the Universe. The rest is the ordinary matter that makes up everything else in the Universe, protons and neutrons for the atoms that form our surroundings, from star dust to burgers.

The initial release of data from the Bolshoi simulation began in early September.

“We’ve released a lot of the data so that other astrophysicists can start to use it,” he said. “So far it’s less than one percent of the actual output, because the total output is so huge, but there will be additional releases in the future.”

One can only wonder how these simulations and theories can be taken into effect if Einstein’s theory of relativity is wrong. More videos related to the Balshoi simulation depicting dark matter and energy halos can be seen on the UCSC’s website.

 

Illustration of where the new SDSS map data exists in space and time.

Astronomers plot largest 3D map of the Universe

Illustration of where the new SDSS map data exists in space and time.

Illustration of where the new SDSS map data exists in space and time.

Unveiled this past weekend, astronomers from the Sloan Digital Sky Survey have created a 3D map of the Universe using the light from 14,000 quasars, some of the brightest bodies in the universe, to illuminate gas clouds in regions of space some 11 billion light years away. From the study‘s abstract:

These features arise as the light from the quasar is absorbed by the intervening neutral hydrogen. This gives one-dimensional information about the fluctuations in the neutral hydrogen density along the line of sight to the quasar. When spectra of many quasars are combined, it allows one to build a three-dimensional image of the fluctuations in the neutral hydrogen density and thus infer the corresponding fluctuations in the matter density.

Previous attempts at creating a working 3D map of the Universe have been with successful results in the past, but they had only gone as far as plotting galaxies 7 billion light-years away from Earth. This new version goes far beyond anything previously attempted in distance and time, as it charts clouds of hydrogen as far as 11 billion light years.

Image courtesy of Sloan Digital Sky Survey

Image courtesy of Sloan Digital Sky Survey

Of course, it’s not like someone will be able to chart through these maps anytime soon, especially considering we’re having difficulties reaching infinitely closer points compared, like Mars, but these mapped out 3D representations will provide absolute invaluable insights towards the formation of the Universe, and help answer numerous puzzling questions astronomers have long been after, including the nature of dark energy.

“We’re looking for a bump in the data that may tell us how fast universe is expanding,” said cosmologist Anže Slosar of Brookhaven National Laboratory, one of the researchers who presented the map May 1 at the American Physical Society meeting in Anaheim, California. “We don’t have enough data to see the bump yet, but we expect to get there in a few years.”

Data for the map was scanned with the help of the Baryon Oscillation Spectroscopic Survey, or BOSS, which can analyze light from individual quasars. The team analyzed 14,000 of about 160,000 known quasars and by 2014 astronomers hope to have 50,000 or 60,000 quasar slices in their grips; enough data, they hope, to finally elaborate a meaningful hypothesis concerning the formation and fate of the Universe. The researchers also plan to release a proper 3-D representation of the data (instead of the 2-D images shown here) for the public by then.

Slice of the full map showing the density of hydrogen gas in the ancient universe. Blue represents little gas, while red represents dense clouds.

Slice of the full map showing the density of hydrogen gas in the ancient universe. Blue represents little gas, while red represents dense clouds.