ESA Euclid mission will study Dark Energy

An artist's concept of the ESA's Euclid misssion to study dark energy.

Credit: ESA/C. Carreau

Euclid is an ESA mission to map the geometry of the dark Universe.

The Euclid mission will investigate the distance-redshift relationship and the evolution of cosmic structures by measuring shapes and redshifts of galaxies and clusters of galaxies out to redshifts ~2, or equivalently to a look-back time of 10 billion years.

To accomplish the Euclid mission ESA has selected Thales Alenia Space (see also the ESA press release) for the construction of the satellite and its Service Module and Airbus Defence and Space (EADS ex-Astrium) for the Payload Module.

Euclid will be equipped with a 1.2 m diameter Silicon Carbide (SiC) mirror telescope made by EADS feeding 2 instruments, VIS and NISP, built by the Euclid Consortium :

• a high quality panoramic visible imager (VIS), 
• a near infrared 3-filter (Y, J and H) photometer (NISP-P) and 
• a slitless spectrograph (NISP-S). 

With these instruments physicists will probe the expansion history of the Universe and the evolution of cosmic structures by measuring the modification of shapes of galaxies induced by gravitational lensing effects of dark matter and the 3-dimension distribution of structures from spectroscopic red­shifts of galaxies and clusters of galaxies.

The satellite will be launched by a Soyuz ST-2.1B rocket and then travel to the L2 Sun-Earth Lagrangian point for a 6 years mission.

Members of the Euclid Consortium at the Euclid Meeting in Leiden.

Credit: ESA

In this way, Euclid will cover the entire period over which dark energy played a significant role in accelerating the expansion.

NASA will also participate in the ESA's Euclid mission in conjunction with it's own WFIRST-AFTA mission, searching for Dark Energy.

Last year, NASA nominated 40 American scientists to join the 14 American scientists already part of the international Euclid Consortium, the team responsible for the science, data production and instruments for the mission. NASA will also provide 16 infrared detectors for the telescope.

Euclid's goal is to understand the nature of dark energy and its role in the expansion of the universe. To do so, it plans to use two complimentary probes to study the phenomenon. The first probe will study weak gravitational lensing, while the second will examine BAOs.

Orbiting at the second Lagrangian point, Euclid will use two instruments to study a wide region of the sky free from the contaminating light from the solar system and the galaxy. It will also observe two "Euclid Deep Fields" of the early universe.

Of the approximately 10 billion sources Euclid intends to observe, more than 1 billion will be studied for weak lensing, while tens of millions of galaxies will be measured for clustering caused by BAOs.

"WFIRST-AFTA and Euclid will make complimentary observations, with WFIRST-AFTA observing fainter galaxies and Euclid observing more sky," Nasa project manager Gehrels said.

"The combined data set will be much larger and more accurate than any other BAO measurement."

When combined with ground-based observations over a variety of wavelengths, the new observations that WFIRST-AFTA and Euclid provide, should bring significant insights into dark energy and the expansion of the universe.

"The best constraints on dark energy in the 2020s will come from a combination of Euclid, WFIRST and ground-based data," WFIRST project manager Rhodes said.

NASA's WFIRST-AFTA: Dark Energy Hunt Combines Powerful New Tools and 2 Missions

An artist's rendition of the proposed WFIRST-AFTA mission, which will study dark energy, extrasolar planets and objects in the near-infrared.

Credit: NASA

Dark energy makes up nearly three-fourths of the universe, driving its accelerating expansion, but the substance is still mysterious to scientists that study it.

In upcoming years, NASA has plans to investigate this powerful force with the new WFIRST-AFTA mission and a strong role in the European Space Agency's Euclid mission.

"NASA has plans for a robust dark energy portfolio over the next decade," Jason Rhodes of the NASA Jet Propulsion Laboratory said during a news conference at the April meeting of the American Physics Society in Savannah, Georgia.


'A tripod of science'
NASA's proposed Wide-Field Infrared Survey Telescope-Astrophysics Focused Telescope Assets, or WFIRST-AFTA, will use five probes to perform three complimentary surveys in its search to clarify the nature of dark energy.

"WFIRST-AFTA is a survey mission to make the most precise measurements on the influence of dark energy and dark matter on the universe," Neil Gehrels, WFIRST project scientist of NASA's Goddard Space Flight Center, told Space.com by email.

Type Ia supernovas are thought to form from the explosion of a white dwarf star. Because these powerful detonations all share similar brightness that can be viewed in distant galaxies, they are regarded as "standard candles" of cosmology. Recording how dim a supernova appears provides an indication of their distance.

WFIRST-AFTA will survey nearly 3,000 Type Ia supernovas to determine how rapidly they are moving away from the Milky Way due to the expansion of the universe. Scientists think dark energy drives this expansion.

"We can trace out how the universe is expanding more rapidly in the current epoch than earlier in the history of the universe and use that to constrain models of dark energy," Gehrels said.

An artist's view shows three different potential methods of forming Type 1a supernovae, the 'standard candles' used to measure the expansion of the universe. 

The first two panels show a white dwarf in a binary system accumulating matter from its larger companion. The panel on the right shows two white dwarfs colliding, a possible third scenario.

Credit: NASA/Swift/ Aurore Simonnet, Sonoma State Univ.

The telescope will also perform a High Latitude Imaging Survey to determine the effects of dark matter structures on the light from distant galaxies.

Einstein predicted, and scientists have subsequently confirmed, that massive structures bend the light coming from objects behind them, serving as a gravitational lens.

Astronomers have used such natural telescopes formed by features such as massive galaxies to study objects throughout the universe.

Dark matter works the same way, bending the light from galaxies that sit behind it. By searching for small distortions of galactic shapes, WFIRST-AFTA will allow scientists to determine the dark matter distribution along the lines of sight.

The third dark energy survey planned for WFIRST-AFTA will study baryonic acoustic oscillations, or BAOs. Ripples of sound waves left over from the early universe grew into the larger structures of the universe over time.

Accurately measuring the position and distance of a hundred million galaxies will map these disturbances to determine the evolution of dark energy over time.

The three complimentary surveys combine to provide a broad portrait of dark energy.

"The combined power of all these probes will give the best understanding of dark energy in the current universe and how it evolved with time as the universe expanded," Gehrels said. "WFIRST-AFTA is the only observatory, space or ground based, that combines all of these probes."

Proposed to launch in the mid-2020s, WFIRST-AFTA is not searching solely for information about dark energy.

Instead, it combines what Gehrels calls "a tripod of science." The telescope will also image planets outside the solar system and perform near-infrared surveys.

ESA Planck and NASA WMAP: Dark energy a mirage concealed behind phantom fields

Observations of ESA's Planck and NASA's WMAP satellites help to solve the equation of the state of dark energy. 

Credit: ESA et al.

Quintessence and phantom fields, two hypotheses formulated using data from satellites, such as ESA's Planck and NASA's Wilkinson Microwave Anisotropy Probe (WMAP), are among the many theories that try to explain the nature of dark energy.

Now researchers from Barcelona and Athens suggest that both possibilities are only a mirage in the observations and it is the quantum vacuum which could be behind this energy that moves our universe.

Cosmologists believe that some three quarters of the universe are made up of a mysterious dark energy which would explain its accelerated expansion.

The truth is that they do not know what it could be, therefore they put forward possible solutions.

One is the existence of quintessence, an invisible gravitating agent that instead of attracting, repels and accelerates the expansion of the cosmos.

WMAP Satellite Diagram

From the Classical World until the Middle Ages, this term has referred to the ether or fifth element of nature, together with earth, fire, water and air.

Another possibility is the presence of an energy or phantom field whose density increases with time, causing an exponential cosmic acceleration.

This would reach such speed that it could break the nuclear forces in the atoms and end the universe in some 20,000 million years, in what is called the Big Rip.

The experimental data that underlie these two hypotheses comes from satellites such as ESA's Planck and NASA's Wilkinson Microwave Anisotropy Probe (WMAP).

Observations from the two probes are essential for solving the so-called equation of the state of dark energy, a characterising mathematical formula, the same as that possessed by solid, liquid and gaseous states.

Now researchers from the University of Barcelona (Spain) and the Academy of Athens (Greece) have used the same satellite data to demonstrate that the behaviour of dark energy does not need to resort to either quintessence or phantom energy in order to be explained.

The details have been published in the Monthly Notices of the Royal Astronomical Society journal.

Joan Solà

"Our theoretical study demonstrates that the equation of the state of dark energy can simulate a quintessence field, or even a phantom field, without being one in reality, thus when we see these effects in the observations from WMAP, Planck and other instruments, what we are seeing is an mirage," told SINC Joan Solà, one of the authors from University of Barcelona.

Nothing fuller than the quantum vacuum
"What we think is happening is a dynamic effect of the quantum vacuum, a parameter that we can calculate," explained the researcher.

The concept of the quantum vacuum has nothing to do with the classic notion of absolute nothingness.

"Nothing is more 'full' than the quantum vacuum since it is full of fluctuations that contribute fundamentally to the values that we observe and measure," Solà pointed out.

The detailed, all-sky picture of the infant universe created from nine years of WMAP data. 

The image reveals 13.77 billion year old temperature fluctuations (shown as colour differences) that correspond to the seeds that grew to become the galaxies. 

The signal from our galaxy was subtracted using the multi-frequency data. This image shows a temperature range of ± 200 microKelvin.

Credit: NASA / WMAP Science Team

These scientists propose that dark energy is a type of dynamical quantum vacuum energy that acts in the accelerated expansion of our universe.

This is in contrast to the traditional static vacuum energy or cosmological constant.

The drawback with this strange vacuum is that it is the source of problems such as the cosmological constant, a discrepancy between the theoretical data and the predictions of the quantum theory that drives physicists mad.

"However, quintessence and phantom fields are still more problematic, therefore the explanation based on the dynamic quantum vacuum could be the more simple and natural one," concluded Solà.

More information: Spyros Basilakos, Joan Sola. "Effective equation of state for running vacuum: "mirage" quintessence and phantom dark energy". Monthly Notices of the Royal Astronomical Society 437(4), February 2014. DOI: 10.1093/mnras/stt2135

AMS Dark Matter: NASA Chief Speaks Out

The news today (April 3) that the International Space Station has played a pivotal role in what could be one of the biggest leaps forward for astrophysics has left the NASA Administrator with nothing but high praise.

The news stems from the station's Alpha Magnetic Spectrometer, which detected signals that just might be evidence of dark matter particles colliding and annihilating each other. (Of course, it could be something else, too.

The science team has not yet confirmed the signal is definitely from dark matter, but it is a tantalizing possibility.)

Here's what Bolden says about today's AMS announcement, which NASA sent out to reporters this afternoon:

"The AMS cosmic ray particle results announced today could help foster a new understanding of the fields of fundamental physics and astrophysics. I am confident that this is only the first of many scientific discoveries enabled by the station that will change our understanding of the universe. Multiple NASA human spaceflight centers around the country played important roles in this work, and we look forward to many more exciting results from AMS. "

"For more than 50 years, NASA has pushed the boundaries beyond Earth to unveil the underlying architecture of the cosmos, revealing new knowledge about our place within it. The International Space Station is a gateway to the universe, teaching us how humans can live, work, and thrive in space as we endeavor to venture deeper into the solar system. "

"It's a remarkable testament that the orbital laboratory could play such an important supporting role in research at the very smallest scale of the physical universe. It's proof positive the space station is humanity's greatest achievement in low-Earth orbit."

The Alpha Magnetic Spectrometer is a complicated (and expensive) instrument launched to the space station in May 2011 on one of NASA's last-ever shuttle missions. The $2 billion instrument is the result of 16 years of work by 200 scientists from 16 different countries and 56 different institutions.

Dark energy and dark matter mysteries - Update

The Mysteries currently facing the Dark Energy Scientists can be compiled into a small list.

• Gravity acting across vast distances does not seem to explain what astronomers see
• Galaxies, for example, should fly apart; some other mass must be there holding them together
• Astrophysicists have thus postulated "dark matter" - invisible to us but clearly acting on galactic scales
• At the greatest distances, the Universe's expansion is accelerating
• Thus we have also "dark energy" which acts to drive the expansion, in opposition to gravity
• The current theory holds that 73% of the Universe is dark energy, 23% is dark matter, and just 4% the kind of matter we know well

For decades, the strange substance called dark matter has teased physicists, challenging conventional notions of the cosmos.

Today, though, scientists believe that with the help of multi-billion-dollar tools, they are closer than ever to piercing the mystery -- and the first clues may be unveiled just weeks from now.

"We are so excited because we believe we are on the threshold of a major discovery," said Michael Turner, director of the Kavli Institute for Cosmological Physics at the University of Chicago, at an annual conference of the American Association for the Advancement of Science (AAAS).

Dark matter throws down the gauntlet to the so-called Standard Model of physics.

Elegant and useful for identifying the stable of particles and forces that regulate our daily life, the Standard Model only tells part of the cosmic story.

For one thing, it does not explain gravity, although we know how to measure gravity and exploit it for our needs.

And the Standard Model has been found to account for only around four or five percent of the stuff in the Universe.

The rest is dark matter, making up 23 percent, and dark energy, an enigmatic force that appears to drive the expansion of the Universe, which accounts for around 72 or 73 percent.

"On the cosmology side we now understand that this mysterious dark matter holds together our galaxy and the rest of the Universe," said Turner.

"And the tantalizing thing on the cosmology side is that we have an airtight case that the dark matter is made of something new... there is no particle in the Standard Model that can account for dark matter."

HEXAGON NASA's Ex-Spy Satellite to Seek out Dark Energy

Astronomers are excited by the possibility of using one of two cast-off spy satellite telescopes gifted to NASA to probe for dark energy.

They have already come up with a design that would incorporate the spy telescope into the proposed Wide Field Infrared Survey Telescope (WFIRST), a high-priority NASA mission that would hunt for dark energy, exoplanets and supernovae.

Though a final review and economic analysis won't be released until April, the new design based on the donated scopes would boost WFIRST's abilities significantly, some researchers say.

But the concept could also require more power and a bigger launch vehicle, potentially raising the project's roughly $1.5 billion price tag.

ESO Dark Energy Camera Image: Barred Spiral Galaxy NGC 1365

This image from the 570-megapixel Dark Energy Camera on a mountaintop in Chile shows the barred spiral galaxy NGC 1365.

The most powerful sky-mapping machine ever created has captured and recorded ancient starlight for the first time.

Picture: FERMILAB/US DEPARTMENT OF ENERGY/AFP/Getty

Sky Survey Map of Massive Galaxies, Distant Black Holes, Clues to Dark Matter and Energy

The Sloan Digital Sky Survey III(SDSS-III) has released the largest-ever three-dimensional map of massive galaxies and distant black holes, helping astronomers better explain the mysterious “dark matter” and “dark energy” that make up 96 percent of the universe. 

According to SDSS-III scientific spokesperson and University of Pittsburgh assistant professor of physics and astronomy Michael Wood-Vasey, scientists using the map, titled Data Release 9 (DR9), can retrace the Universe’s history over the last seven billion years. 

Wood-Vasey co-wrote the DR9 summary paper featured on the arXiv database.

“This is science at its collaborative best,” said Wood-Vasey. “SDSS-III scientists work together to address big questions extending from our own galaxy to distant reaches of the Universe, and then they share that data with the world to allow anyone to make the next big discovery.”

The new DR9 map of the Universe includes images of 200 million galaxies and spectra measurements of how much light galaxies gives off at different wavelengths— of 1.35 million galaxies, including new spectra of 540,000 galaxies dating from when the universe was half its present age.

Researchers at SDSS-III say that studying spectra is important because it allows scientists to figure out how much the Universe has expanded since the light left each galaxy.

Additionally, having this new data to analyze not only helps researchers understand the distant Universe, and the Earth’s own Milky Way Galaxy.

DR9 includes better estimates regarding the temperatures and chemical compositions of more than a half million stars in the Milky Way.

DR9 represents the latest in a series of data releases stretching back to 2001. This release includes new data from the ongoing SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), which will eventually measure the positions of 1.5 million massive galaxies over the past seven billion years of cosmic time, as well as 160,000 quasars—giant black holes feeding on stars and gas—from as long ago as 12 billion years.

While all of these new images and spectra contain the promise of new discoveries about the universe, SDSS-III is only in the middle of its six-year survey and will release three times as much data by the time it has completed its work, in 2014.

All the newly released data is now available on the DR9 Web site, at http://www.sdss3.org/dr9.

Additionally, the SkyServer Web site includes lesson plans for teachers who use DR9 data to teach astronomy and other topics in science, technology, and mathematics.