Posted on by Shannon Hall

Mapping Dark Matter 4.5 Billion Light-years Away

This image shows the galaxy MCS J0416.1–2403, one of six clusters targeted by the Hubble Frontier Fields programme. The blue in this image is a mass map created by using new Hubble observations combined with the magnifying power of a process known as gravitational lensing. In red is the hot gas detected by NASA’s Chandra X-Ray Observatory and shows the location of the gas, dust and stars in the cluster. The matter shown in blue that is separate from the red areas detected by Chandra consists of what is known as dark matter, and which can only be detected directly by gravitational lensing.Credit: ESA/Hubble, NASA, HST Frontier Fields. Acknowledgement: Mathilde Jauzac (Durham University, UK) and Jean-Paul Kneib (École Polytechnique Fédérale de Lausanne, Switzerland).

The Milky Way measures 100 to 120 thousand light-years across, a distance that defies imagination. But clusters of galaxies, which comprise hundreds to thousands of galaxies swarming under a collective gravitational pull, can span tens of millions of light-years.

These massive clusters are a complex interplay between colliding galaxies and dark matter. They seem impossible to map precisely. But now an international team of astronomers using the NASA/ESA Hubble Space Telescope has done exactly this — precisely mapping a galaxy cluster, dubbed MCS J0416.1–2403, 4.5 billion light-years away.

“Although we’ve known how to map the mass of a cluster using strong lensing for more than twenty years, it’s taken a long time to get telescopes that can make sufficiently deep and sharp observations, and for our models to become sophisticated enough for us to map, in such unprecedented detail, a system as complicated as MCS J0416.1–2403,” said coauthor Jean-Paul Kneib in a press release.

Measuring the amount and distribution of mass within distant objects can be extremely difficult. Especially when three quarters of all matter in the Universe is dark matter, which cannot be seen directly as it does not emit or reflect any light. It interacts only by gravity.

But luckily large clumps of matter warp and distort the fabric of space-time around them. Acting like lenses, they appear to magnify and bend light that travels past them from more distant objects.

This effect, known as gravitational lensing, is only visible in rare cases and can only be spotted by the largest telescopes. Even galaxy clusters, despite their massive size, produce minimal gravitational effects on their surroundings. For the most part they cause weak lensing, making even more distant sources appear as only slightly more elliptical across the sky.

However, when the alignment of the cluster and distant object is just right, the effects can be substantial. The background galaxies can be both brightened and transformed into rings and arcs of light, appearing several times in the same image. It is this effect, known as strong lensing, which helped astronomers map the mass distribution in MCS J0416.1–2403.

“The depth of the data lets us see very faint objects and has allowed us to identify more strongly lensed galaxies than ever before,” said lead author Dr Jauzac. “Even though strong lensing magnifies the background galaxies they are still very far away and very faint. The depth of these data means that we can identify incredibly distant background galaxies. We now know of more than four times as many strongly lensed galaxies in the cluster than we did before.”

Using Hubble’s Advanced Camera for Surveys, the astronomers identified 51 new multiply imaged galaxies around the cluster, quadrupling the number found in previous surveys. This effect has allowed Jauzac and her colleagues to calculate the distribution of visible and dark matter in the cluster and produce a highly constrained map of its mass.

The total mass within the cluster is 160 trillion times the mass of the Sun, with an uncertainty of 0.5%. It’s the most precise map ever produced.

But Jauzac and colleagues don’t plan on stopping here. An even more accurate picture of the galaxy cluster will have to include measurements from weak lensing as well. So the team will continue to study the cluster using ultra-deep Hubble imaging.

They will also use ground-based observatories to measure any shifts in galaxies’ spectra and therefore note the velocities of the contents of the cluster. Combining all measurements will not only further enhance the detail, but also provide a 3D model of the galaxies within the cluster, shedding light on its history and evolution.

This work has been accepted for publication in the Monthly Notices of the Royal Astronomy and is available online.

Posted on by Shannon Hall

Missing Light Crisis: The Universe Seems a Little Too Dark

The Milky Way as seen from Devil's Tower, Wyoming. Image Credit: Wally Pacholka

There are few moments more breathtaking than standing beneath a brilliant starry sky. Thousands of small specks of light mark only the beginning of the vast cosmic arena, with its unimaginable vistas of time and space. The Milky Way, wrapping above in a cosmic sheet of colors and patterns, also hints that there’s more than meets the eye.

Most of us long for these dark nights, far away from the city lights. But a new study suggests the Universe is a little too dark.

The vast reaches of empty space are bridged by filaments of hydrogen and helium. But there’s a disconnect between how bright the large-scale structure of the Universe is expected to be and how bright it actually is.

In a recent study, a team of astronomers led by Juna Kollmeier from the Carnegie Institute for Science found the light from known populations of stars and quasars is not nearly enough to explain observations of intergalactic hydrogen.

In a brightly lit Universe, intergalactic hydrogen will be easily destroyed by energetic photons, meaning images of the large-scale structure will actually appear dimmer. Whereas in a dim Universe, there are fewer photons to destroy the intergalactic hydrogen and images will appear brighter.

Hubble Space Telescope observations of the large-scale structure show a brightly lit Universe. But supercomputer simulations using only the known sources of ultraviolet light produces a dimly lit Universe. The difference is a stunning 400 percent.

Computer simulations of intergalactic hydrogen in a "dimly lit" universe (left) and a "brightly lit" universe (right) that has five times more of the energetic photons that destroy neutral hydrogen atoms. Hubble Space Telescope observations of hydrogen absorption match the picture on the right, but using only the known astronomical sources of ultraviolet light produces the much thicker structures on the left, and a severe mismatch with the observations. Image is credited to Ben Oppenheimer and Juna Kollmeier.
Computer simulations of intergalactic hydrogen in a “dimly lit” universe (left) and a “brightly lit” universe (right) that has five times more of the energetic photons that destroy neutral hydrogen atoms. Image Credit: Ben Oppenheimer / Juna Kollmeier.

Observations indicate that the ionizing photons from hot, young stars are almost always absorbed by gas in the host galaxy, so they never escape to affect intergalactic hydrogen. The necessary culprit could be the known number of quasars, which is far lower than needed to produce the required light.

“Either our accounting of the light from galaxies and quasars is very far off, or there’s some other major source of ionizing photons that we’ve never recognized,” said Kollmeier in a press release. “We are calling this missing light the photon underproduction crisis. But it’s the astronomers who are in crisis — somehow or other, the universe is getting along just fine.”

Strangely, this mismatch only appears in the nearby, relatively well-studied cosmos. In the early Universe, everything adds up.

“The simulations fit the data beautifully in the early universe, and they fit the local data beautifully if we’re allowed to assume that this extra light is really there,” said coauthor Ben Oppenheimer from the University of Colorado. “It’s possible the simulations do not reflect reality, which by itself would be a surprise, because intergalactic hydrogen is the component of the Universe that we think we understand the best.”

So astronomers are attempting to shed light on the missing light.

“The most exciting possibility is that the missing photons are coming from some exotic new source, not galaxies or quasars at all,” said coauthor Neal Katz from the University of Massachusetts at Amherst.

The team is exploring these new sources with vigor. It’s possible that there could be an undiscovered population of quasars in the nearby Universe. Or more exotically, the photons could be created from annihilating dark matter.

“The great thing about a 400 percent discrepancy is that you know something is really wrong,” said coauthor David Weinberg from Ohio State University. “We still don’t know for sure what it is, but at least one thing we thought we knew about the present day universe isn’t true.”

The results were published in The Astrophysical Journal Letters and are available online.

Posted on by Nancy Atkinson

Intriguing X-Ray Signal Might be Dark Matter Candidate

A mysterious X-ray signal in the Perseus galaxy cluster. Credit: NASA/CXC/SAO/E.Bulbul, et al.

Could a strange X-ray signal coming from the Perseus galaxy cluster be a hint of the elusive dark matter in our Universe?

Using archival data from the Chandra X-ray Observatory and the XMM-Newton mission, astronomers found an unidentified X-ray emission line, or a spike of intensity at a very specific wavelength of X-ray light. This spike was also found in 73 other galaxy clusters in XMM-Newton data.

The scientists propose that one intriguing possibility is that the X-rays are produced by the decay of sterile neutrinos, a hypothetical type of neutrino that has been proposed as a candidate for dark matter and is predicted to interact with normal matter only via gravity.

“We know that the dark matter explanation is a long shot, but the pay-off would be huge if we’re right,” said Esra Bulbul of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts, who led the study. “So we’re going to keep testing this interpretation and see where it takes us.”

Astronomers estimate that roughly 85 percent of all matter in the Universe is dark matter, invisible to even the most powerful telescopes, but detectable by its gravitational pull.

Galaxy clusters are good places to look for dark matter. They contain hundreds of galaxies as well as a huge amount of hot gas filling the space between them. But measurements of the gravitational influence of galaxy clusters show that the galaxies and gas make up only about one-fifth of the total mass. The rest is thought to be dark matter.

Bulbul explained in a post on the Chandra blog that she wanted try hunting for dark matter by “stacking” (layering observations on top of each other) large numbers of observations of galaxy clusters to improve the sensitivity of the data coming from Chandra and XMM-Newton.

“The great advantage of stacking observations is not only an increased signal-to-noise ratio (that is, the amount of useful signal compared to background noise), but also the diminished effects of detector and background features,” wrote Bulbul. “The X-ray background emission and instrumental noise are the main obstacles in the analysis of faint objects, such as galaxy clusters.”

Her primary goal in using the stacking technique was to refine previous upper limits on the properties of dark matter particles and perhaps even find a weak emission line from previously undetected metals.

“These weak emission lines from metals originate from the known atomic transitions taking place in the hot atmospheres of galaxy clusters,” said Bulbul. “After spending a year reducing, carefully examining, and stacking the XMM-Newton X-ray observations of 73 galaxy clusters, I noticed an unexpected emission line at about 3.56 kiloelectron volts (keV), a specific energy in the X-ray range.”

In theory, a sterile neutrino decays into an active neutrino by emitting an X-ray photon in the keV range, which can be detectable through X-ray spectroscopy. Bulbul said that her team’s results are consistent with the theoretical expectations and the upper limits placed by previous X-ray searches.

Bulbul and her colleagues worked for a year to confirm the existence of the line in different subsamples, but they say they still have much work to do to confirm that they’ve actually detected sterile neutrinos.

“Our next step is to combine data from Chandra and JAXA’s Suzaku mission for a large number of galaxy clusters to see if we find the same X-ray signal,” said co-author Adam Foster, also of CfA. “There are lots of ideas out there about what these data could represent. We may not know for certain until Astro-H launches, with a new type of X-ray detector that will be able to measure the line with more precision than currently possible.”

Astro-H is another Japanese mission scheduled to launch in 2015 with a high-resolution instrument that should be able to see better detail in the spectra, and Bulbul said they hope to be able to “unambiguously distinguish an astrophysical line from a dark matter signal and tell us what this new X-ray emission truly is.”

Since the emission line is weak, this detection is pushing the capabilities Chandra and XMM Newton in terms of sensitivity. Also, the team says there may be explanations other than sterile neutrinos if this X-ray emission line is deemed to be real. There are ways that normal matter in the cluster could have produced the line, although the team’s analysis suggested that all of these would involve unlikely changes to our understanding of physical conditions in the galaxy cluster or the details of the atomic physics of extremely hot gases.

The authors also note that even if the sterile neutrino interpretation is correct, their detection does not necessarily imply that all of dark matter is composed of these particles.

The Chandra press release shared an interesting behind-the-scenes look into how science is shared and discussed among scientists:

Because of the tantalizing potential of these results, after submitting to The Astrophysical Journal the authors posted a copy of the paper to a publicly accessible database, arXiv. This forum allows scientists to examine a paper prior to its acceptance into a peer-reviewed journal. The paper ignited a flurry of activity, with 55 new papers having already cited this work, mostly involving theories discussing the emission line as possible evidence for dark matter. Some of the papers explore the sterile neutrino interpretation, but others suggest different types of candidate dark matter particles, such as the axion, may have been detected.

Only a week after Bulbul et al. placed their paper on the arXiv, a different group, led by Alexey Boyarsky of Leiden University in the Netherlands, placed a paper on the arXiv reporting evidence for an emission line at the same energy in XMM-Newton observations of the galaxy M31 and the outskirts of the Perseus cluster. This strengthens the evidence that the emission line is real and not an instrumental artifact.

Further reading:
Paper by Bulbul et al.
Chandra press release
ESA press release
Chandra blog

Posted on by Elizabeth Howell

Could This Be The Signal Of Dark Matter? Unsure Scientists Checking This Out

An intriguing signal could be due to "dark matter annihilations" pops up on the left of this data gathered by NASA's Fermi Gamma-ray Space Telescope. The image on left shows the galactic center in gamma rays with energies between 1 and 3.16 GeV. Red indicates the most activity, and the labels are for pulsars. The image at right has all these gamma-ray sources removed. Credit: T. Linden, Univ. of Chicago

Sometimes a strange signal comes from the dark and it takes a while to figure out what that signal means. In this case, scientists analyzing high-energy gamma rays emanating from the galaxy’s center found an unexplained source of emission that they say is “consistent with some forms of dark matter.”

The data came courtesy of NASA’s Fermi Gamma-ray Space Telescope and was analyzed by a group of independent scientists. They found that by removing all known sources of gamma rays, they were left with gamma-ray emissions that so far, they cannot explain. More observations will be needed to characterize these emissions, they cautioned.

Scientists aren’t even sure what dark matter (which can only be detected through gravitational effects) is made of. One theoretical candidate could be something called Weakly Interacting Massive Particles (WIMPs), which could produce gamma rays in ranges that Fermi could detect.

Also, the location of the radiation at the galaxy’s center is an interesting spot, since scientists believe that’s where dark matter would lurk since the insofar invisible substance would be the base of normal structures like galaxies.

“The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it,” stated Dan Hooper, an astrophysicist at Fermilab and lead author of the study.

“The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models.”

The scientists suggest that if WIMPs were destroying each other, this would be “a remarkable fit” for a dark matter signal. They again caution, though, that there could be other explanations for the phenomenon.

“Dark matter in this mass range can be probed by direct detection and by the Large Hadron Collider (LHC), so if this is dark matter, we’re already learning about its interactions from the lack of detection so far,” stated co-author Tracy Slatyer, a theoretical physicist at the Massachusetts Institute of Technology.

“This is a very exciting signal, and while the case is not yet closed, in the future we might well look back and say this was where we saw dark matter annihilation for the first time.”

You can read more about the research in Physical Review D or in preprint form on Arxiv.

Source: NASA

Posted on by Fraser Cain

Weekly Space Hangout – March 7, 2014: Cosmos Premiere & NASA Budget

Host: Fraser Cain
Astrojournalists: David Dickinson, Matthew Francis, Casey Dreier, Jason Major, Brian Koberlein, Alan Boyle

This week’s stories:

Alan Boyle (@b0yle, cosmiclog.com ):
Cosmos premiere!

David Andrew Dickinson (@astroguyz):
Watch the Close Pass of NEO 2014 DX110
Daylight Saving time: A Spring Forward or a Step Back?
A Natural Planetary Defense Against Solar Storms

Matthew Francis (@DrMRFrancis, BowlerHatScience.org):
Using gravitational lensing to measure a spinning quasar
CosmoAcademy classes

Casey Dreier (Planetary.org):
The 2015 NASA Budget Request
NASA Kinda Embraces Exploring Europa

Jason Major (@JPMajor, LightsInTheDark.com):
That’s the way the asteroid crumbles

Brian Koberlein (@briankoberlein, briankoberlein.com):
*Possible* evidence for dark matter WIMPs
Black Holes exceed Eddington limit
Using quasars in a quantum experiment

We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.

Posted on by Shannon Hall

Astronomers Map Dark Matter Throughout the Entire Universe

Full sky map of the cosmic microwave background. The color red indicates a cool spot while the color blue indicates a hot spot. Image credit: NASA.

Warped visions of the cosmic microwave background – the earliest detectable light – allow astronomers to map the total amount of visible and invisible matter throughout the universe.

Roughly 85 percent of all matter in the universe is dark matter, invisible to even the most powerful telescopes, but detectable by its gravitational pull.

In order to find dark matter, astronomers look for an effect called gravitational lensing: when the gravitational pull of dark matter bends and amplifies light from a more distant object. In its most eccentric form it results in multiple arc-shaped images of distant cosmic objects.

The Hubble Space Telescope shows the effect of gravitational lensing as background galaxies are warped by the galaxy cluster MACS J1206. Image Credit: NASA
The Hubble Space Telescope shows the effect of gravitational lensing as background galaxies are warped by the galaxy cluster MACS J1206. Image Credit: NASA

But there’s one caveat here: in order to detect dark matter there must be an object directly behind it. The ‘stars’ have to be aligned.

In a recent study led by Dr. James Geach of the University of Hertfordshire in the United Kingdom, astronomers have set their eyes on the cosmic microwave background (CMB) instead.

“The CMB is the most distant/oldest light we can see,” Dr. Geach told Universe Today. “It can be thought of as a surface, backlighting the entire universe.”

The photons from the CMB have been hurling toward the Earth since the universe was only 380,000 years old. A single photon has had the chance to run into plenty of matter, having effectively probed all the matter in the universe along its line of sight.

“So our view of the CMB is a bit distorted from what it intrinsically looks like – a bit like looking at the pattern on the bottom of a swimming pool,” Dr. Geach said.

By noting the small distortions in the CMB, we can probe all of the dark matter throughout the entire universe. But doing just this is extremely challenging.

The team observed the southern sky with the South Pole Telescope, a 10 meter telescope designed for observations in the microwave. This large, groundbreaking survey produced a CMB map of the southern sky, which was consistent with previous CMB data from the Planck satellite.

The characteristic signatures of gravitational lensing by intervening matter can not be extracted by eye. Astronomers relied on the use of a well-developed mathematical procedure. We wont go into the nasty details.

This produced a “map of the total projected mass density between us and the CMB. That’s quite incredible if you think about it – it’s an observational technique to map all of the mass in the universe, right back to the CMB,” Dr. Geach explained.

But the team didn’t finish their analysis there. Instead, they continued to measure the CMB lensing at the positions of quasars – powerful supermassive black holes in the centers of the earliest galaxies.

“We found that regions of the sky with a large density of quasars have a clearly stronger CMB lensing signal, implying that quasars are indeed located in large-scale matter structures,” Dr. Ryan Hickox of Dartmouth College – second author on the study – told Universe Today.

Finally, the CMB map was used to determine the mass of these dark matter halos. These results matched those determined in older studies, which looked at how the quasars clustered together in space, with no reference to the CMB at all.

Consistent results between two independent measurements is a powerful scientific tool. According to Dr. Hickox, it shows that “we have a strong understanding of how supermassive black holes reside in large-scale structures, and that (once again) Einstein was right.”

The paper has been accepted for publication in the Astrophysical Journal Letters and is available for download here.

Posted on by Jason Major

An “Elemental” Explanation of Dark Matter

Image from Dark Universe, showing the distribution of dark matter in the universe. Credit: AMNH

Atoms, string theory, dark matter, dark energy… there’s an awful lot about the Universe that might make sense on paper (to physicists, anyway) but is extremely difficult to detect and measure, at least with the technology available today. But at the core of science is observation, and what’s been observed of the Universe so far strongly indicates an overwhelming amount of… stuff… that cannot be observed. But just because it can’t be seen doesn’t mean it’s not there; on the contrary, it’s what we can’t see that actually makes up the majority of the Universe.

If this doesn’t make sense, that’s okay — they’re all pretty complex concepts. So in order to help non-scientists (which, like dark energy, most of the population is comprised of) get a better grasp as to what all this “dark” stuff is about, CERN scientist and spokesperson James Gillies has teamed up with TED-Ed animators to visually explain some of the Universe’s darkest secrets. Check it out above (and see more space science lessons from TED-Ed here.)

Because everything’s easier to understand with animation!

Lesson by James Gillies, animation by TED-Ed.

Posted on by Nancy Atkinson

New Video Map Shows Large-Scale Cosmic Structure out to 300 million Light Years

Map showing all galaxies in the local universe color-coded by their distance to us: blue galaxies are the closest, and red are farther, up to 300 million light-years away. Credit: University of Hawaii.

Researchers with the Cosmic Flows project have been working to map both visible and dark matter densities around our Milky Way galaxy up to a distance of 300 million light-years, and they’ve now released this new video map which shows the motions of structures of the nearby Universe in greater detail than ever before.

“The complexity of what we are seeing is almost overwhelming,” says researcher Hélène Courtois, associate professor at the University of Lyon, France, and associate researcher at the Institute for Astronomy (IfA), University of Hawaii (UH) at Manoa. Courtois narrates the video.

The video zooms into our local area of the Universe — our Milky Way galaxy lies in a supercluster of 100,000 galaxies — and then slowly draws back to show the cosmography of the Universe out to 300 million light years.

The map shows how the large-scale structure of the Universe is a complex web of clusters, filaments, and voids. Large voids are bounded by filaments that form superclusters of galaxies. These are the largest structures in the universe.

The team explains:

The movements of the galaxies reveal information about the main constituents of the Universe: dark energy and dark matter. Dark matter is unseen matter whose presence can be deduced only by its effect on the motions of galaxies and stars because it does not give off or reflect light. Dark energy is the mysterious force that is causing the expansion of the universe to accelerate.

Read more about this video here, and read the team’s paper here.

Cosmography of the Local Universe from Daniel Pomarède on Vimeo.

Posted on by Ken Kremer

NASA Experiment Seeks Signatures of Formation of First Stars and Galaxies

NASA’s CIBER experiment seeks clues to the formation of the first stars and galaxies. It will study the total sky brightness, to probe the component from first stars and galaxies using spectral signatures, and searches for the distinctive spatial pattern seen in this image, produced by large-scale structures from dark matter. This shows a numerical simulation of the density of matter when the universe was one billion years old. Galaxies formation follows the gravitational wells produced by dark matter, where hydrogen gas coalesces, and the first stars ignite. Credit: Volker Springel/Virgo Consortium.

When did the first stars and galaxies form in the universe and how brightly did they burn?

Scientists are looking for tell-tale signs of galaxy formation with an experimental payload called CIBER.

NASA will briefly turn night into day near midnight along the mid-Atlantic coastline on June 4 – seeking answers to illuminate researchers theories about the beginnings of our Universe with the launch of the Cosmic Infrared Background ExpeRiment (CIBER) from NASA’s launch range at the Wallops Flight Facility along Virginia’s eastern shoreline. See viewing map below.

CIBER will blast off atop a powerful four stage Black Brant XII suborbital rocket at 11 PM EDT Tuesday night, June 4. The launch window extends until 11:59 PM EDT.

Currently the weather forecast is excellent.

The public is invited to observe the launch from an excellent viewing site at the NASA Visitor Center at Wallops which will open at 9:30 PM on launch day.

The night launch will be visible to spectators along a long swath of the US East coast from New Jersey to North Carolina; if the skies are clear as CIBER ascends to space to an altitude of over 350 miles and arcs over on a southeasterly trajectory.

Backup launch days are available from June 5 through 10.

Launch visibility map for the CIBER payload launch from NASA Wallops, Va, on June 4, 2013 at 11 PM EDT. Credit: NASA
Launch visibility map for the CIBER payload launch from NASA Wallops, Va, on June 4, 2013 at 11 PM EDT. Credit: NASA

“The objectives of the experiment are of fundamental importance for astrophysics: to probe the process of first galaxy formation. The measurement is extremely difficult technically,” said Jamie Bock, CIBER principal investigator from the California Institute of Technology

Over the past several decades more than 20,000 sounding rockets have blasted off from an array of launch pads at Wallops, which is NASA’s lead center for suborbital science.

The Black Brant XII sounding rocket is over 70 feet tall.

The launch pad sits adjacent to the newly constructed Pad 0A of the Virginia Spaceflight Authority from which the Orbital Sciences Antares rocket blasted off on its maiden flight on April 21, 2013.

“The first massive stars to form in the universe produced copious ultraviolet light that ionized gas from neutral hydrogen. CIBER observes in the near infrared, as the expansion of the universe stretched the original short ultraviolet wavelengths to long near-infrared wavelengths today.”

“CIBER investigates two telltale signatures of first star formation — the total brightness of the sky after subtracting all foregrounds, and a distinctive pattern of spatial variations,” according to Bock.

Preparing the CIBER instrument for flight. The optics and detectors are cooled by liquid nitrogen to -19C (77 K, -312F) during the flight to eliminate infrared emission from the instrument and to achieve the best detector sensitivity. Photo: NASA/Berit Bland
Preparing the CIBER instrument for flight. The optics and detectors are cooled by liquid nitrogen to -19C (77 K, -312F) during the flight to eliminate infrared emission from the instrument and to achieve the best detector sensitivity. Photo: NASA/Berit Bland

This will be the fourth launch of CIBER since 2009 but the first from Wallops. The three prior launches were all from the White Sands Missile Range, N.M. and in each case the payload was recovered and refurbished for reflight.

However the June 4 launch will also be the last hurrah for CIBER.

The scientists are using a more powerful Black Brant rocket to loft the payload far higher than ever before so that it can make measurements for more than twice as long as ever before.

The consequence of flying higher is that CIBER will splashdown in the Atlantic Ocean, about 400 miles off the Virgina shore and will not be recovered.

You can watch the launch live on NASA Ustream beginning at 10 p.m. on launch day at: http://www.ustream.com/channel/nasa-wallops

I will be onsite at Wallops for Universe Today.

And don’t forget to “Send Your Name to Mars” aboard NASA’s MAVEN orbiter- details here. Deadline: July 1, 2013

Ken Kremer

…………….
Learn more about Conjunctions, Mars, Curiosity, Opportunity, MAVEN, LADEE and NASA missions at Ken’s upcoming lecture presentations

June 4: “Send your Name to Mars on MAVEN” and “CIBER Astro Sat, LADEE Lunar & Antares Rocket Launches from Virginia”; Rodeway Inn, Chincoteague, VA, 8:30 PM

June 11: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; NJ State Museum Planetarium and Amateur Astronomers Association of Princeton (AAAP), Trenton, NJ, 730 PM.

June 12: “Send your Name to Mars on MAVEN” and “LADEE Lunar & Antares Rocket Launches from Virginia”; Franklin Institute and Rittenhouse Astronomical Society, Philadelphia, PA, 8 PM.

NASA’s CIBER payload will launch from a suborbital launch pad located directly behind this Antares rocket erected at Pad 0A at the NASA Wallops Flight Facility along the Eastern shore of Virginia. Only a few hundred feet of beach sand and a miniscule sea wall separate the Wallops Island pads from the Atlantic Ocean waves and Mother Nature. Credit: Ken Kremer (kenkremer.com)
NASA’s CIBER payload will launch from a suborbital launch pad located directly behind this Antares rocket erected at Pad 0A at the NASA Wallops Flight Facility along the Eastern shore of Virginia. Only a few hundred feet of beach sand and a miniscule sea wall separate the Wallops Island pads from the Atlantic Ocean waves and Mother Nature.
Credit: Ken Kremer (kenkremer.com)
Posted on by Jason Major

Researchers May Have Finally Detected a Dark Matter Particle

The international Super Cryogenic Dark Matter Search (SuperCDMS) has detected what may be the particle that's thought to make up dark matter throughout the Universe.

Dark matter: it’s invisible, it’s elusive, it’s controversial… and it’s everywhere — in the Universe, yes, but especially in the world of astrophysics, where researchers have been exhaustively trying to reveal its true identity for decades.

Now, scientists with the international Super Cryogenic Dark Matter Search (SuperCDMS) experiment are reporting the detection of a particle that’s thought to make up dark matter: a weakly-interacting massive particle, or WIMP. According to a press release from Texas A&M University (whose high-energy physicist Rupak Mahapatra is a principal investigator in the experiment) SuperCDMS has identified a WIMP-like signal at the 3-sigma level, which indicates a 99.8 percent chance of an actual discovery — a “concrete hint,” as it’s being called.

“In high-energy physics, a discovery is only claimed at 5-sigma or better,” Mahapatra said. “So this is certainly very exciting, but not fully convincing by the standards. We just need more data to be sure. For now, we have to live with this tantalizing hint of one of the biggest puzzles of our time.”

If this is indeed a WIMP it will be the first time such a particle has been directly observed, lending more insight into what dark matter is… or isn’t.

Notoriously elusive, WIMPs rarely interact with normal matter and therefore are difficult to detect. Scientists believe they occasionally bounce off, or scatter like billiard balls from, atomic nuclei, leaving behind a small amount of energy capable of being tracked by detectors deep underground, particle colliders such as the Large Hadron Collider at CERN and even instruments in space like the Alpha Magnetic Spectrometer (AMS) mounted on the International Space Station.

A stack of crystal germanium CDMS detectors (Fermilab)
A stack of crystal germanium CDMS detectors (Fermilab)

The CDMS experiment, located a half-mile underground at the Soudan mine in northern Minnesota and managed by the United States Department of Energy’s Fermi National Accelerator Laboratory, has been searching for dark matter since 2003. The experiment uses very sophisticated detector technology and advanced analysis techniques to enable cryogenically cooled (almost absolute zero temperature at -460 degrees F) germanium and silicon targets to search for the rare recoil of dark matter particles.

This newly-announced detection actually comes from data acquired during an earlier phase of the experiment.

“This result is from data taken a few years ago using silicon detectors manufactured at Stanford that are now defunct,” Mahapatra said. “Increased interest in the low mass WIMP region motivated us to complete the analysis of the silicon-detector exposure, which is less sensitive than germanium for WIMP masses above 15 giga-electronvolts [one GeVa is equal to a billion electron volts] but more sensitive for lower masses. The analysis resulted in three events, and the estimated background is 0.7 events.”

Although Mahapatra says the result is certainly encouraging and worthy of further investigation, he cautions it should not be considered a discovery just yet.

“We are only 99.8 percent sure, and we want to be 99.9999 percent sure,” Mahapatra said. “At 3-sigma, you have a hint of something. At 4-sigma, you have evidence. At 5-sigma, you have a discovery.”

“In medicine, you can say you are curing 99.8 percent of the cases, and that’s OK. When you say you’ve made a fundamental discovery in high-energy physics, you can’t be wrong.”

– Dr. Rupak Mahapatra, SuperCDMS principal investigator, Texas A&M University

Advanced 6-inch silicon detectors developed by Mahapatra's lab at Texas A&M
Advanced 6-inch silicon detectors developed by Mahapatra’s lab at Texas A&M

The collaboration will continue to probe this WIMP sector using the SuperCDMS Soudan experiment’s operating germanium detectors and is considering using larger, more advanced 6-inch silicon detectors developed at the Texas A&M’s Department of Electrical Engineering in future experiments.

The team has detailed its results in a paper published in arXiv that eventually will appear in Physical Review Letters. Mahapatra will also announce the results today at 12 p.m. CDT in a talk at the Mitchell Institute for Fundamental Physics and Astronomy.

Source: Texas A&M University

(Read more about dark matter here and here.)