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  • richardmitnick 8:38 pm on April 17, 2015 Permalink | Reply
    Tags: , , Dark Energy Survey,   

    From FNAL- “Frontier Science Result: DES Reticulum II: Welcome to the neighborhood” 

    FNAL Home

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    April 17, 2015
    Alex Drlica-Wagner

    1
    This plot shows the positions of stars surrounding the newly discovered dwarf galaxy Reticulum II. Points outlined in black represent stars for which high-resolution optical spectra provided velocity measurements. Red points represent stars that were confirmed to be members of the new dwarf galaxy, while gray points are non-members. (Points that are not outlined do not have velocity measurements.)

    The number of dark matter-dominated Milky Way satellite dwarf galaxies was increased by one this week. Scientists discovered the newest dwarf galaxy, Reticulum II, in data from the Dark Energy Survey.

    Dark Energy Survey
    Dark Energy Camera
    DES and DECam, the camera built at FNAL

    However, the DES data alone were not enough to confirm that Reticulum II was indeed a dark matter-dominated dwarf galaxy. Determining the dark matter content of Reticulum II required an extensive campaign combining observations from some of the largest telescopes in the world.

    Researchers determine the dark matter content of dwarf galaxies by measuring the velocities of the stars in these objects. The higher the velocity of the stars, the more mass is required to keep the stars gravitationally bound. Stellar velocities are determined from the Doppler shift of elemental lines, which produce sharp features in the spectrum of visible light coming from the stars. Reticulum II was targeted with high- and medium-resolution spectroscopy by the Magellan 6.5-meter telescope, the Gemini 8.1-meter telescope and the VLT 8.2-meter telescope, all located in Chile.

    Magellan 6.5 meter telescopes
    Magellan 6.5 meter Interior
    Magellan 6.5 meter telescope

    Gemini South telescope
    Gemini South Interior
    Gemini South

    ESO VLT Interferometer
    ESO VLT Interior
    ESO/VLT

    The result: Reticulum II has 470 times more mass than can be accounted for by its stars alone. This makes Reticulum II the first spectroscopically confirmed dwarf galaxy discovered outside of the Sloan Digital Sky Survey.

    If dark matter is composed of weakly interacting massive particles, it may annihilate to produce Standard Model particles, including gamma rays.

    3
    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    Regions of high dark matter density, such as dwarf galaxies, would then shine in gamma rays produced from dark matter annihilation. The strength of the gamma ray signal from each dwarf galaxy would be related to the distance and dark matter content of that galaxy. While nearby and highly dark matter-dominated, Reticulum II actually has a smaller dark matter content than several other previously known dwarf galaxies. This makes it unlikely to detect a gamma ray signal from dark matter annihilation in Reticulum II without seeing a similar signal in other nearby dwarf galaxies with greater dark matter content.

    In addition to Reticulum II, researchers have found seven more dwarf galaxy candidates in the DES data. Since March 10, three additional dwarf galaxy candidates were announced using data from other surveys. Interestingly, two of these three additional candidates used the Dark Energy Camera for photometric confirmation. While spectroscopy is necessary to confirm that these candidates are indeed dwarf galaxies, it is already clear that DECam is a powerful instrument for understanding dark matter.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 8:42 am on April 14, 2015 Permalink | Reply
    Tags: , Dark Energy Survey, ,   

    From FNAL: “Mapping the cosmos: Dark Energy Survey creates detailed guide to spotting dark matter” 

    FNAL Home

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Media contacts:

    Andre Salles, Fermilab Office of Communication, 630-840-3351, media@fnal.gov

    Science contacts:

    Josh Frieman, director of the Dark Energy Survey, 847-274-0429, frieman@fnal.gov
    Chihway Chang, ETH Zurich, +41-798101425, chihway.chang@phys.ethz.ch
    Bhuvnesh Jain, University of Pennsylvania, 267-973-7063, bjain@physics.upenn.edu
    Gary Bernstein, University of Pennsylvania, 215-573-6252, garyb@physics.upenn.edu

    Analysis will help scientists understand the role that dark matter plays in galaxy formation

    1
    This is the first Dark Energy Survey map to trace the detailed distribution of dark matter across a large area of sky. The color scale represents projected mass density: red and yellow represent regions with more dense matter. The dark matter maps reflect the current picture of mass distribution in the universe where large filaments of matter align with galaxies and clusters of galaxies. Clusters of galaxies are represented by gray dots on the map – bigger dots represent larger clusters. This map covers three percent of the area of sky that DES will eventually document over its five-year mission. Image: Dark Energy Survey

    Dark Energy Survey
    Dark Energy Camera
    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    Dark Energy Survey; Camera, built at FNAL; and CTIO Victor M Blanco 4 meter telescope which houses the DECam Camera

    Scientists on the Dark Energy Survey have released the first in a series of dark matter maps of the cosmos. These maps, created with one of the world’s most powerful digital cameras, are the largest contiguous maps created at this level of detail and will improve our understanding of dark matter’s role in the formation of galaxies. Analysis of the clumpiness of the dark matter in the maps will also allow scientists to probe the nature of the mysterious dark energy, believed to be causing the expansion of the universe to speed up.

    The new maps were released today at the April meeting of the American Physical Society in Baltimore, Maryland. They were created using data captured by the Dark Energy Camera, a 570-megapixel imaging device that is the primary instrument for the Dark Energy Survey (DES).

    Dark matter, the mysterious substance that makes up roughly a quarter of the universe, is invisible to even the most sensitive astronomical instruments because it does not emit or block light. But its effects can be seen by studying a phenomenon called gravitational lensing – the distortion that occurs when the gravitational pull of dark matter bends light around distant galaxies. Understanding the role of dark matter is part of the research program to quantify the role of dark energy, which is the ultimate goal of the survey.

    This analysis was led by Vinu Vikram of Argonne National Laboratory (then at the University of Pennsylvania) and Chihway Chang of ETH Zurich. Vikram, Chang and their collaborators at Penn, ETH Zurich, the University of Portsmouth, the University of Manchester and other DES institutions worked for more than a year to carefully validate the lensing maps.

    “We measured the barely perceptible distortions in the shapes of about 2 million galaxies to construct these new maps,” Vikram said. “They are a testament not only to the sensitivity of the Dark Energy Camera, but also to the rigorous work by our lensing team to understand its sensitivity so well that we can get exacting results from it.”

    The camera was constructed and tested at the U.S. Department of Energy’s Fermi National Accelerator Laboratory and is now mounted on the 4-meter Victor M. Blanco telescope at the National Optical Astronomy Observatory’s Cerro Tololo Inter-American Observatory in Chile. The data were processed at the National Center for Supercomputing Applications at the University of Illinois in Urbana-Champaign.

    The dark matter map released today makes use of early DES observations and covers only about three percent of the area of sky DES will document over its five-year mission. The survey has just completed its second year. As scientists expand their search, they will be able to better test current cosmological theories by comparing the amounts of dark and visible matter.

    Those theories suggest that, since there is much more dark matter in the universe than visible matter, galaxies will form where large concentrations of dark matter (and hence stronger gravity) are present. So far, the DES analysis backs this up: The maps show large filaments of matter along which visible galaxies and galaxy clusters lie and cosmic voids where very few galaxies reside. Follow-up studies of some of the enormous filaments and voids, and the enormous volume of data, collected throughout the survey will reveal more about this interplay of mass and light.

    “Our analysis so far is in line with what the current picture of the universe predicts,” Chang said. “Zooming into the maps, we have measured how dark matter envelops galaxies of different types and how together they evolve over cosmic time. We are eager to use the new data coming in to make much stricter tests of theoretical models.”

    View the Dark Energy Survey analysis.

    The Dark Energy Survey is a collaboration of more than 300 scientists from 25 institutions in six countries. Its primary instrument, the Dark Energy Camera, is mounted on the 4-meter Blanco telescope at the National Optical Astronomy Observatory’s Cerro Tololo Inter-American Observatory in Chile, and its data is processed at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign.

    Funding for the DES Projects has been provided by the U.S. Department of Energy Office of Science, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, ETH Zurich for Switzerland, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência e Tecnologia, the Deutsche Forschungsgemeinschaft and the collaborating institutions in the Dark Energy Survey. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2012-39559, ESP2013-48274, FPA2013-47986 and Centro de Excelencia Severo Ochoa SEV-2012-0234, some of which include ERDF funds from the European Union.

    Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at http://www.fnal.gov and follow us on Twitter at @Fermilab.

    The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 10:43 am on March 12, 2015 Permalink | Reply
    Tags: , , Dark Energy Survey,   

    From DES: “The best of the best” Old but Worth it 

    Dark Energy Icon
    The Dark Energy Survey

    1

    Det. Josh Frieman [Fermilab and the University of Chicago]

    The clearest skies give the best images and provide the best clues to cosmic expansion

    Scroll down through Dark Energy Detectives case files, and you’ll see beautiful images of galaxies taken with the Dark Energy Camera.

    Dark Energy Camera
    DECam, built at FNAL

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco telescope in Chile houses the DECam

    While they come in different shapes, sizes, and colors, these galaxies all have one thing in common: they’re all speeding away from our own Milky Way, at speeds of tens to hundreds of millions of miles per hour. The Universe is expanding, something we’ve known for nearly 90 years.

    If we could track the speeds of each of these galaxies over time, what would we find: would they stay the same, speed up, or slow down? Since the Milky Way’s gravity tugs on them, [Sir]Isaac Newton would have told us they would slow down over time, just as an apple thrown straight up in the air slows down (and eventually falls) due to the pull of Earth’s gravity. But Isaac would have been wrong, the galaxies are getting faster, not slower. The expansion of the Universe is speeding up, something we’ve known for only 17 years. The 300 detectives of the Dark Energy Survey (DES) are embarked on a five-year mission to understand why this is happening. In this quest, they’re carrying out the largest survey of the cosmos ever undertaken.

    While these goals sound lofty and profound (and they are), at its core DES is really about taking pictures. Lots of them. On a typical night, DES detectives snap about 250 photos of the sky. After five years, we’ll have over 80,000 photos in our album. For each snapshot, the camera shutter is kept open for about a minute and a half to let in enough light from distant galaxies. On each image, you can count about 80,000 galaxies. When we put them all together, and accounting for the fact that we’ll snap each part of the sky about 50 times, that adds up to pictures of about 200 million galaxies, give or take.

    One of the ways we’ll learn about dark energy—the putative stuff causing the universe to speed up—is by measuring the shapes of those 200 million galaxies very precisely and comparing them to each other. Imagine taking photos of 200 million people, roughly one out of every 35 people on Earth, to learn about the diversity of the human race. To gain the most information about our species, you will want all of your photos to be taken by a professional photographer under identical conditions conducive to getting the best image: good lighting, camera perfectly in focus, no jiggling of the camera or movement of your human subject during the exposure, etc. But inevitably, with 200 million photos, given the vagaries of people and circumstance, some photos will come out better than others. In some, the subject may be a bit blurred. In others, there may be too much or too little background light to see the person clearly.

    In the Dark Energy Survey, we’re striving to get the best, clearest snapshots of these 200 million galaxies that we can. As professional photographers of the night sky (a.k.a. astronomers), we’re using the best equipment there is—the Dark Energy Camera, which we built ourselves—to do the job. The camera has 570 Megapixels and 5 large lenses. It has a sophisticated auto-focus mechanism to always give us the crispest images possible.

    No need for a flash, since galaxies burn with the light of billions of suns.

    But as with human photography, Nature doesn’t always cooperate. The Dark Energy Camera is mounted on the Blanco telescope, located at Cerro Tololo in the Chilean Andes. This site has mostly very clear nights, but occasionally, clouds roll by. Turbulence in the atmosphere, which makes stars twinkle, leads to a slight blurring of the images of stars and galaxies, even if the camera is in perfect focus. The camera works by taking pictures of all the light that reflects off the 4-meter-diameter mirror of the telescope. If a cold front moves through, making the air in the telescope dome cooler than the 15-ton mirror, plumes of hot air rising off the mirror lead to blurry images. The sharpest images are those taken straight overhead—the further away from straight up that we point the telescope, the more atmosphere the light has to pass through, again increasing the blurring; since our survey covers a large swath of the sky, we cannot always point straight up. Strong wind blowing in through the open slit of the dome can cause the telescope to sway slightly during an exposure, also blurring the picture. Since the Earth rotates around its axis, during an exposure the massive telescope must compensate by continuously, very smoothly moving to stay precisely locked on to its target; any deviation in its motion will—you guessed it—blur the image.

    For all these reasons and others, the quality of the DES images varies. On some nights, conditions conspire to give us very crisp images. On others, the images are a bit more blurred than we’d like, making it harder to measure the shapes of those distant galaxies. If an image is too blurred, we don’t include it in the album: we’ll come back another night to take a photo of those particular galaxies. So far, about 80% of the photos we’ve taken have been good enough to keep.

    Most nights during our observing season, we have three detectives operating the camera; each of us is there for about a week, and in the course of a season about 50 detectives rotate through, taking their “shifts.” On the night of January 27, 2015, I was in the middle of my week-long observing shift at the telescope with two fellow detectives, Yuanyuan Zhang from the University of Michigan and Andrew Nadolski from the University of Illinois at Urbana-Champaign. That night, Andrew was manning the camera, I was checking the quality of the images as they were taken, and Yuanyuan was our boss.

    The conditions that night were outstanding. Although it was a bit humid, the atmosphere was extremely smooth and stable. We were mainly taking pictures using filters that let in only very red or near-infrared light. This was because the moon was up, and the moon is actually quite blue: red filters block most of the moonlight that scatters off the atmosphere from entering the camera, enabling us to see red galaxies against the dark night sky. In his famous photograph “Monolith, the Face of Half Dome” taken in Yosemite National Park, Ansel Adams used a red (but not infrared) filter to darken the blue daytime sky to dramatic effect.

    At 12:28 am local time, we snapped exposure number 403841, using a near-infrared filter called the z-band. The z-band is so red that it’s beyond the visible spectrum that can be seen by the human eye, but digital cameras, and the Dark Energy Camera in particular, are very sensitive to near-infrared light. Computers at the telescope analyze each image right after it’s taken and display the results on a bank of monitors, so we can tell whether we’re taking data that passes muster for our cosmic album. When 403841 came out, the screen showed that it was an exceptionally sharp image. Further analysis convinced us that it was in fact the sharpest image of the roughly 35,000 snapshots that DES has taken so far, going back two years to the beginning of the survey.

    The image was so sharp that the light from each star was spread out over only about 0.6 seconds of arc or about 0.00017 degrees. For comparison, that’s how big a crater a kilometer across on the surface of the moon looks from Earth. It’s also the angular size of a typical human hair seen at a distance of about 100 feet.

    A small portion of the 403841 image is shown above in false color, showing a great spiral galaxy plus a number of smaller, fainter galaxies and a few bright stars in our own Milky Way. The star inside the red circle at the lower right of the image has its light spread out over only 0.6 arc seconds. While not as pretty as the color images of galaxies in other DED case files, this is closer to what a raw image directly from the camera looks like. The raw DES digital images are sent for processing to the National Center for Supercomputing Applications in Urbana-Champaign, Illinois (if you’re under 40, ask your parents if they remember sending film out for processing), to make them science-ready for our fellow DES detectives.

    In DES, we keep a “bragging rights” web page of the sharpest images we have taken in each of the five filters we use. Our friend 403841 is now prominently displayed there—the best of the best. But the best thing about records is that they’re made to be broken.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    Dark Energy Camera

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and [has mounted] it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Started in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

     
  • richardmitnick 4:57 pm on January 6, 2015 Permalink | Reply
    Tags: , , , , Dark Energy Survey   

    From DES: “Our dark, tangled web: Clues of dark energy” 

    Dark Energy Icon
    The Dark Energy Survey

    d
    Lurking beneath a sea of light, an intricate pattern rustles and changes ever so slowly. It is built from dark, and nearly invisible, cosmic forces. Amidst the clumps and knots of galaxies lay empty, usually fallow spaces. While each galaxy, with its billions of stars, has a unique story of birth and evolution, we don’t miss the forest for the trees. Taken as a whole, the pattern of clusters and voids in our galaxy maps can tell us about the dark forces that shape our universe.

    m
    Mapping of galaxies by the Sloan Digital Sky Survey out to 2 billion light-years away. Red and green points indicate positions of galaxies, with red points having a larger density of galaxies. The fully black areas on the sides are parts of the sky inaccessible to the survey.

    Looking at the image from the Dark Energy Camera (above), we can see a plethora of celestial objects, including many blue, red and yellow smudges, many of which are distant galaxies. It may appear that these galaxies are randomly strewn about the cosmos. However, astronomers charting the locations of these galaxies across large distances have found that galaxies are organized into structures, into cosmic patterns that can span swaths of space and time much larger than what is seen in this image. The figure [above], from the Sloan Digital Sky Survey, shows a map of millions of galaxies. These galaxies appear to cluster into knots and filaments (areas with many galaxies), and leave behind voids (areas with few or no galaxies). Some filamentary structures stretch across a billion light-years – 60 trillion times the distance from the Earth to the Sun!

    DECam
    DECam, built at FNAL

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    The Victor M Blanco Telescope (CTIO) in Chile houses DECam

    Like any good detective, we cannot ignore a pattern. How do galaxies, separated by up to billions of light-years, eventually coalesce into the great cosmic structures we see today? It turns out the ‘mastermind’ of this cosmic operation is a familiar friend (and foe) to us on Earth: the force of gravity.

    Using computer simulations, astronomers have investigated how gravity acts among so many galaxies over such very large distances. The Millennium Simulation, and others like it, show that a mostly random distribution of matter will naturally cluster into filaments and voids through the force of gravity. When we statistically compare the simulation results to our data (observations of many galaxies), the patterns are the same: gravity’s influence throughout the visible universe has fostered this grand filamentary structure, which has been dubbed, “The Cosmic Web.”


    Millennium simulation

    The Millennium Simulation: brighter areas are where more matter and galaxies have concentrated. (See more of this simulation in this fly-through video).

    What does this mean for the detectives working on the Dark Energy Survey? It turns out that gravity has a nemesis in its goal for creating web-like order across the universe: dark energy, the invisible force causing the accelerated expansion of space throughout the universe. The faster space grows and accelerates, the greater the distances galaxies must travel to form filaments and clusters. If there is more dark energy, gravity needs more time to pull galaxies together, and web-like structure develops slowly. If there is no dark energy, the web gets built quickly. By studying how quickly or slowly the cosmic web was built across time, we learn how strong dark energy has been and if it is growing stronger or weaker.

    The battle between gravity and dark energy, manifested in the evolving structure of the cosmic web, is a key way to study dark energy. In fact, the cosmic web is particularly important for answering one specific question: is there even dark energy at all?!

    Most astronomers agree that there is overwhelming evidence for the accelerated expansion of the universe. For many reasons, the most plausible source of this acceleration is some new force or otherwise unseen, “dark” energy. The leading alternative theory though is a change in the laws of gravity (specifically, in [Albert] Einstein’s laws of general relativity). Since physicists and astronomers have tested Einstein’s laws numerous times on Earth, the Solar System, and within galaxies, the change would only manifest itself at much larger distance scales. It could be causing the appearance of cosmic acceleration, such that there might be no dark energy.

    This second hypothesis would re-write our case file on the cosmic web. Perhaps instead of fighting against dark energy, gravity is just not carrying quite the influence across billions of light years that we’ve predicted. Measurements of the cosmic web, in conjunction with other measures of cosmic acceleration, will be key in telling us whether our universe is a battleground for dark energy and gravity, or if gravity is just different than previously thought. Either conclusion (or perhaps an even stranger one!) would signify a fundamental revision in how we think about the workings of our universe.

    As the Dark Energy Survey collects more beautiful images of hundreds of millions of galaxies over a five-year span, our detectives will be carefully logging their positions, charting out the cosmic web, hoping to identify what forces are at work in the dark.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    Dark Energy Camera

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and [has mounted] it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Started in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

     
  • richardmitnick 2:50 pm on December 24, 2014 Permalink | Reply
    Tags: , , , , Dark Energy Survey,   

    From The Dark Energy Survey: ” Our dark, tangled web: Clues of dark energy” 

    Dark Energy Icon
    The Dark Energy Survey

    December 24, 2014
    Detective Ross Cawthon (University of Chicago)
    Image: Det.’s Marty Murphy and Reidar Hahn (FNAL)

    ds

    Lurking beneath a sea of light, an intricate pattern rustles and changes ever so slowly. It is built from dark, and nearly invisible, cosmic forces. Amidst the clumps and knots of galaxies lay empty, usually fallow spaces. While each galaxy, with its billions of stars, has a unique story of birth and evolution, we don’t miss the forest for the trees. Taken as a whole, the pattern of clusters and voids in our galaxy maps can tell us about the dark forces that shape our universe.

    s
    Sloan Digital Sky Survey: Galaxy Map
    Mapping of galaxies by the Sloan Digital Sky Survey out to 2 billion light-years away. Red and green points indicate positions of galaxies, with red points having a larger density of galaxies. The fully black areas on the sides are parts of the sky inaccessible to the survey. (See [below] also the SDSS fly-through.)

    Looking at the image from the Dark Energy Camera (above), we can see a plethora of celestial objects, including many blue, red and yellow smudges, many of which are distant galaxies. It may appear that these galaxies are randomly strewn about the cosmos. However, astronomers charting the locations of these galaxies across large distances have found that galaxies are organized into structures, into cosmic patterns that can span swaths of space and time much larger than what is seen in this image. The figure above], from the Sloan Digital Sky Survey, shows a map of millions of galaxies. These galaxies appear to cluster into knots and filaments (areas with many galaxies), and leave behind voids (areas with few or no galaxies). Some filamentary structures stretch across a billion light-years – 60 trillion times the distance from the Earth to the Sun!

    Like any good detective, we cannot ignore a pattern. How do galaxies, separated by up to billions of light-years, eventually coalesce into the great cosmic structures we see today? It turns out the ‘mastermind’ of this cosmic operation is a familiar friend (and foe) to us on Earth: the force of gravity.

    Using computer simulations, astronomers have investigated how gravity acts among so many galaxies over such very large distances. The Millennium Simulation, and others like it, show that a mostly random distribution of matter will naturally cluster into filaments and voids through the force of gravity. When we statistically compare the simulation results to our data (observations of many galaxies), the patterns are the same: gravity’s influence throughout the visible universe has fostered this grand filamentary structure, which has been dubbed, “The Cosmic Web.”

    ms
    Millennium simulation: http://www.mpa-garching.mpg.de/galform/virgo/millennium/seqB_063a_half.jpg
    The Millennium Simulation: brighter areas are where more matter and galaxies have concentrated. (See more of this simulation in this fly-through video).

    What does this mean for the detectives working on the Dark Energy Survey? It turns out that gravity has a nemesis in its goal for creating web-like order across the universe: dark energy, the invisible force causing the accelerated expansion of space throughout the universe. The faster space grows and accelerates, the greater the distances galaxies must travel to form filaments and clusters. If there is more dark energy, gravity needs more time to pull galaxies together, and web-like structure develops slowly. If there is no dark energy, the web gets built quickly. By studying how quickly or slowly the cosmic web was built across time, we learn how strong dark energy has been and if it is growing stronger or weaker.

    The battle between gravity and dark energy, manifested in the evolving structure of the cosmic web, is a key way to study dark energy. In fact, the cosmic web is particularly important for answering one specific question: is there even dark energy at all?!

    Most astronomers agree that there is overwhelming evidence for the accelerated expansion of the universe. For many reasons, the most plausible source of this acceleration is some new force or otherwise unseen, “dark” energy. The leading alternative theory though is a change in the laws of gravity (specifically, in [Albert] Einstein’s laws of general relativity). Since physicists and astronomers have tested Einstein’s laws numerous times on Earth, the Solar System, and within galaxies, the change would only manifest itself at much larger distance scales. It could be causing the appearance of cosmic acceleration, such that there might be no dark energy.

    This second hypothesis would re-write our case file on the cosmic web. Perhaps instead of fighting against dark energy, gravity is just not carrying quite the influence across billions of light years that we’ve predicted. Measurements of the cosmic web, in conjunction with other measures of cosmic acceleration, will be key in telling us whether our universe is a battleground for dark energy and gravity, or if gravity is just different than previously thought. Either conclusion (or perhaps an even stranger one!) would signify a fundamental revision in how we think about the workings of our universe.

    As the Dark Energy Survey collects more beautiful images of hundreds of millions of galaxies over a five-year span, our detectives will be carefully logging their positions, charting out the cosmic web, hoping to identify what forces are at work in the dark.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    Dark Energy Camera

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and [has mounted it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Started in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

     
  • richardmitnick 5:44 pm on October 28, 2014 Permalink | Reply
    Tags: , , , , Dark Energy Survey,   

    From Dark Energy Detectives: “Across the world and up all night” 

    Dark Energy Icon
    The Dark Energy Survey

    Undated

    For the last week, detectives from the Dark Energy Survey have been coordinating across four continents to bring to light more evidence of how the fabric of spacetime is stretching and evolving.

    In Sussex, England, over 100 detectives met to discuss the current state and the future of the Survey that is conducted at the Blanco telescope, located at Cerro Tololo in Chile. At this semi-annual collaboration meeting (with a new venue each time), we continued to strategize analyses for the many probes of spacetime evolution and dark energy: as I write, several early results are being prepared for publication.

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco telescope, home of the DECam

    At Cerro Tololo, a team of observers operated the Dark Energy Camera (DECam) on the Blanco telescope, as we make our way through the second season of observing for the Survey. Each season goes August through February, during the Chilean summer.

    DECam
    DECam, built at Fermilab

    The Anglo-Australian Telescope at Siding Spring Observatory in Australia is home to the OzDES Survey – long-term project for obtaining highly precise distance measurements of objects discovered by DES, such as supernovae and galaxy clusters. These “follow-up” measurements will be very important evidence in pinning down the culprit for dark energy.

    Anglo Australian Telescope Exterior
    Anglo Australian Telescope Interior
    Anglo Australian Telescope at Siding Spring Observatory

    At Cerro Pachon, just east of Cerro Tololo, another team of two agents began to search for evidence of highly warped space in the distant cosmos, using the Gemini (South) Telescope (@GeminiObs). We spent six nights working to measure highly accurate distances of strong gravitational lensing systems. These systems are galaxies or groups of galaxies that are massive enough to significantly distort the fabric of space-time. Space and time are so warped that the light rays from celestial objects – like galaxies and quasars – behind these massive galaxies become bent. The resulting images in DECam become stretched or even multiplied – just like an optical lens. In future case reports, we’ll expand on this phenomenon in more detail.

    Gemini South telescope
    Gemini South Interior
    Gemini South

    All the while, supercomputers the National Center for Supercomputing Applications (NCSA) are processing the data from DECam each night, turning raw images into refined data – ready for analysis by the science teams.

    image
    The image above doesn’t display any obvious strong lenses, but it is an example of the exquisite lines of evidence that DES continues to accumulate each night.

    Here are positions of some of the galaxies above. What information can you find about them? There are several electronic forensic tools to assist your investigation (for example, http://ned.ipac.caltech.edu/forms/nearposn.html; take care to enter the positions with the correct formatting, as they are below). Tweet your findings to our agents at @darkenergdetec, and we can compare case notes.

    RA: 304.3226d, Dec: -52.7966d

    RA: 304.2665d, Dec: -52.6728d

    RA: 304.0723d, Dec: -52.7044d

    Good night, and keep looking up,

    Det. B. Nord

    Det. M. Murphy [image processing]

    See the full article here.

    Dark Energy Camera

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and will mount it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Starting in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

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  • richardmitnick 10:39 am on October 15, 2014 Permalink | Reply
    Tags: , Dark Energy Survey, , ,   

    From FNAL: “From the Center for Particle Astrophysics – Big eyes” 


    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Wednesday, Oct. 15, 2014

    ch
    Craig Hogan, head of the Center for Particle Astrophysics, wrote this column.

    To create small things you need particles with lots of energy, and to learn about them you need to capture and study lots of particles. So it is not surprising that the worldwide physics community is in the business of building giant accelerators and detectors..

    We also find out about new physics without using accelerators by studying the biggest system of all — the cosmos. Such experiments also need big detectors, in particular, giant cameras to make deep, wide-field maps of cosmic structure. For example, Fermilab’s Dark Energy Camera (DECam) is now collecting data for the Dark Energy Survey, using light from distant galaxies gathered by the 4-meter Blanco telescope on Cerro Tololo in Chile. Designed for depth, speed, sensitivity and scientific precision, it’s a behemoth compared to the camera in your phone. By the time you add up all the parts — the detectors, the lenses, the cooling systems, the electronics and the structure to hold them precisely in place 50 feet up in the telescope beam — you have a machine that weighs about 10 tons. That may not seem very big compared to the Tevatron or the thousand-ton telescope the camera is mounted on, but it’s a lot for a digital camera — the biggest ever built.

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco 4 meter telescope

    DECam
    DECam

    FNALTevatron
    Tevatron

    The giant telescope simulator used to test DECam has recently been removed from the Fermilab building where the camera was put together. In the same space, another giant camera will soon start to take shape. This one will study the cosmic microwave background — the primordial light from the big bang. That light has been cooled by the cosmic expansion to microwave wavelengths, so the camera detectors and even its lenses must be cold to match. About 15,000 advanced superconducting detectors from Argonne National Laboratory will be integrated into a camera system about as big as DECam and then shipped for an experiment to take place under the thin, cold, crystalline skies at the South Pole.

    Cosmic Background Radiation Planck
    CMB from ESA/Planck

    ESA Planck
    ESA Planck schematic
    ESA/Planck

    This machine — the SPT-3G camera — will also be the largest of its kind ever built. When it is finished, it will be installed on the South Pole Telescope, where it will map the faint ripples of polarization imprinted on the light since it was created almost 14 billion years ago.

    South Pole Telescope
    South Pole Telescope

    The SPT-3G experiment will advance cosmic mapping by an order of magnitude, but it is also a stepping stone along a path to an even larger Stage 4 CMB project in the following decade. That project, endorsed by the P5 report and supported by a nationwide collaboration of labs and university groups now forming, will carry out a comprehensive survey of the primordial radiation over much of the sky and teach us about new physics ranging from neutrino masses to dark energy.

    See the full article here.

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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  • richardmitnick 2:40 pm on September 15, 2014 Permalink | Reply
    Tags: , , , , Dark Energy Survey   

    From The Dark Energy Survey: “Distant Wanderer” 

    Dark Energy Icon
    The Dark Energy Survey

    Dark Energy Detectives

    No Date
    Det. D. Gerdes

    After a great journey, a long-hidden member of our solar system has returned. Not since the 9th century, when Charlemagne ruled as Emperor of the Holy Roman Empire and Chinese culture flourished under the Tang Dynasty, has this small icy world re-entered the realm of the outer planets.

    wandersr

    This distant wanderer is among first of its kind discovered with data from the Dark Energy Survey (DES). Now officially known as 2013 TV158, it first came into view on October 14, 2013, and has been observed several dozen more times over the following 10 months as it slowly traces the cosmic path laid out for it by Newton’s law of gravitation. We see this small object move in the animation to the left, comprised of a pair of images taken two hours apart in August, 2014.

    It takes almost 1200 years for 2013 TV158 to orbit the sun, and it is probably a few hundred kilometers across – about the length of the Grand Canyon.

    In eight more years, it will make its closest approach to the sun – still a billion kilometers beyond Neptune. At this distance, the sun would shine with less than a tenth of a percent of its brightness here on earth, and would appear no larger than a dime seen from a hundred feet away.

    That’s what high noon looks like on 2013 TV158.

    Then it will begin its six-century outbound journey, slowly fading from the view of even the most powerful telescopes, eventually reaching a distance of nearly 30 billion kilometers before pirouetting toward home again sometime in the 27th century.

    This object is just one of countless tiny worlds that inhabit the frozen outer region of the solar system called the Kuiper Belt, an expanse 20 times as wide and many times more massive than the asteroid belt between Mars and Jupiter. The dwarf planet Pluto also calls the Kuiper Belt its home. The orbits of Jupiter, Pluto and 2013 TV158 around the sun can be seen in the image to the lower right.

    kb
    Known objects in the Kuiper belt, derived from data from the Minor Planet Center. Objects in the main belt are colored green, whereas scattered objects are colored orange. The four outer planets are blue. Neptune’s few known trojans are yellow, whereas Jupiter’s are pink. The scattered objects between Jupiter’s orbit and the Kuiper belt are known as centaurs. The scale is in astronomical units. The pronounced gap at the bottom is due to difficulties in detection against the background of the plane of the Milky Way.

    Scientists believe that these Kuiper Belt Objects, or KBOs, are relics from the formation of the solar system, cosmic leftovers that never merged into one of the larger planets. By studying them, we can gain a better understanding of the processes that gave birth to the solar system 4.5 billion years ago.

    image
    Because they are so distant and faint, KBOs are extremely difficult to detect. The first KBO, Pluto, was discovered in 1930. Sixty-two years would pass before astronomers found the next one. Astronomers have identified well over half a million objects in the main asteroid belt between Mars and Jupiter. To date, we know of only about 1500 KBOs.

    DES is designed to peer far beyond our galaxy, to find millions of galaxies and thousands of supernovae, but it can also do much more. DES records images of ten specific patches of the sky each week between August and February. These images are a perfect hunting ground for KBOs, which move slowly enough that they can stay in the same field of view for weeks or even months. This allows us to look for objects that appear in different places on different nights, and eventually track the orbit over many nights of observations.

    So far we’ve searched less than one percent of the DES survey area for new KBOs. Who knows what other distant new worlds will wander into view?

    Det. D. Gerdes

    Dark Energy Camera
    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    The Dark Energy camera, DECam, built at Fermilab, and its home, the Victor M.Blanco 4m Telescope in Chile

    See the full article here.

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and will mount it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Starting in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

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  • richardmitnick 1:45 pm on September 12, 2014 Permalink | Reply
    Tags: , , , , Dark Energy Survey,   

    From FNAL- “Frontier Science Result: DES Dark Energy Survey discovers new trans-Neptunian objects” 


    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    Friday, Sept. 12, 2014
    David Gerdes, University of Michigan

    three
    Planet hunters, from left: Zhilu Zhang (Carleton College), David Gerdes (University of Michigan) and Ross Jennings (Carleton College)

    Ever wish you could spend your summer vacation exploring someplace cool? Undergraduate students Ross Jennings and Zhilu Zhang, both of Carleton College, got to explore one of the coolest places in the solar system when they accepted research fellowships at the University of Michigan to work with Professor David Gerdes on a search for trans-Neptunian minor planets with the Dark Energy Survey. This faraway region of the solar system, more than five billion kilometers from the sun, is populated by thousands of small, icy worlds that take centuries to complete one orbit. These trans-Neptunian objects (TNOs) are believed to be leftovers from the primordial cloud that gave birth to the solar system.

    two
    These side-by-side images show the new minor planet 2013 QO95. The circled object in the left picture is roughly 200 kilometers in size and lies just beyond Pluto. The bright star in the image is too faint to be seen with the unaided eye. Images: Dark Energy Survey

    Dark Energy Camera
    Dark Energy Camera on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes.

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco 4m Telescope

    To look for TNOs in Dark Energy Survey data, Gerdes and his students examined the 10 fields that DES visits roughly every five days to search for type Ia supernovae. This search uses difference imaging software to detect transient objects such as a supernova that brightens rapidly and then fades over the next few months. But it’s also the perfect tool to find TNOs, which move from night to night against the background of fixed stars, yet slowly enough that they can stay in the same field of observation for weeks.

    Gerdes, Jennings and Zhang started with a list of nearly 100,000 observations of individual transients, then linked different combinations with trial orbits to see which ones were consistent with a TNO. As more and more points were added to each candidate orbit, the team refined their calculations and made improved predictions for additional observations. By the end of the summer, the team had discovered five new TNOs.

    The properties of the new objects reflect the rich dynamical structure of the trans-Neptunian region: One orbits the sun once for every two orbits of Neptune, and another makes two orbits for every five of Neptune. These orbital resonances protect the objects from disruptive close encounters with the giant planet. A third object has a highly elongated, 1,200-year orbit that is among the 50 longest orbital periods known. (Read more about the fourth and fifth objects.)

    In the course of this summer project, the students learned a variety of skills, from Python programming to the mechanics of submitting results for publication.

    But the most important thing, said Zhang, was this: “You need to really have a lot of enthusiasm for the research you are involved in, because there is a lot of repetition and tedious work involved in research, and it is not about discovering new things every day. However, the joy you get after you finally find something is so special that I haven’t felt anything like that before in my entire life.”

    Now that’s cool.

    See the full article here.

    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics.

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  • richardmitnick 3:41 pm on August 18, 2014 Permalink | Reply
    Tags: , , , , Dark Energy Survey,   

    From Symmetry: “Dark Energy Survey kicks off second season” 

    Symmetry

    August 18, 2014
    No Writer Credit

    On August 15, with its successful first season behind it, the Dark Energy Survey collaboration began its second year of mapping the southern sky in unprecedented detail. Using the Dark Energy Camera, a 570-megapixel imaging device built by the collaboration and mounted on the Victor M. Blanco Telescope in Chile, the survey’s five-year mission is to unravel the fundamental mystery of dark energy and its impact on our universe.

    CTIO Victor M Blanco 4m Telescope
    Victor M Blanco 4m Telescope

    Dark Energy Camera
    Dark Energy Camera

    Along the way, the survey will take some of the most breathtaking pictures of the cosmos ever captured. The survey team has announced two ways the public can see the images from the first year.

    Today, the Dark Energy Survey relaunched its photo blog, Dark Energy Detectives. Once every two weeks during the survey’s second season, a new image or video will be posted to http://www.darkenergydetectives.org with an explanation provided by a scientist. During its first year, Dark Energy Detectives drew thousands of readers and followers, including more than 46,000 followers on its Tumblr site.

    Starting on September 1, the one-year anniversary of the start of the survey, the data collected by DES in its first season will become freely available to researchers worldwide. The data will be hosted by the National Optical Astronomy Observatory. The Blanco Telescope is hosted at the National Science Foundation’s Cerro Tololo Inter-American Observatory, the southern branch of NOAO.

    In addition, the hundreds of thousands of individual images of the sky taken during the first season are being analyzed by thousands of computers at the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, Fermi National Accelerator Laboratory and Lawrence Berkeley National Laboratory. The processed data will also be released in coming months.

    Scientists on the survey will use these images to unravel the secrets of dark energy, the mysterious substance that makes up 70 percent of the mass and energy of the universe. Scientists have theorized that dark energy works in opposition to gravity and is responsible for the accelerating expansion of the universe.

    “The first season was a resounding success, and we’ve already captured reams of data that will improve our understanding of the cosmos,” says DES Director Josh Frieman of Fermilab and the University of Chicago. “We’re very excited to get the second season under way and continue to probe the mystery of dark energy.”

    While results on the survey’s probe of dark energy are still more than a year away, a number of scientific results have already been published based on data collected with the Dark Energy Camera.

    The first scientific paper based on Dark Energy Survey data was published in May by a team led by Ohio State University’s Peter Melchior. Using data that the survey team acquired while putting the Dark Energy Camera through its paces, they used a technique called gravitational lensing to determine the masses of clusters of galaxies.

    In June, Dark Energy Survey researchers from the University of Portsmouth and their colleagues discovered a rare superluminous supernova in a galaxy 7.8 billion light years away. A group of students from the University of Michigan discovered five new objects in the Kuiper Belt, a region in the outer reaches of our solar system, including one that takes over a thousand years to orbit the Sun.

    kuiper
    Kuiper Belt

    In February, Dark Energy Survey scientists used the camera to track a potentially hazardous asteroid that approached Earth. The data was used to show that the newly discovered Apollo-class asteroid 2014 BE63 would pose no risk.

    Several more results are expected in the coming months, says Gary Bernstein of the University of Pennsylvania, project scientist for the Dark Energy Survey.

    The Dark Energy Camera was built and tested at Fermilab. The camera can see light from more than 100,000 galaxies up to 8 billion light-years away in each crystal-clear digital snapshot.

    “The Dark Energy Camera has proven to be a tremendous tool, not only for the Dark Energy Survey, but also for other important observations conducted year-round,” says Tom Diehl of Fermilab, operations scientist for the Dark Energy Survey. “The data collected during the survey’s first year—and its next four—will greatly improve our understanding of the way our universe works.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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