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  • 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
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    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
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    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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  • richardmitnick 9:23 am on July 10, 2014 Permalink | Reply
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    From Fermilab- “The sky is not the limit: DES gets time on Gemini telescope” 


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

    Thursday, July 10, 2014
    Hanae Armitage

    In an ambitious five-year mission, the Dark Energy Survey team has devoted itself to mapping the southern sky in unprecedented detail, ultimately hoping to decipher what may stand as the most bewildering phenomenon of our expanding universe.

    In March, DES applied to the Large and Long Program at the Gemini Observatory, a program meant to foster scientific exploration through global collaboration. Although the Gemini Observatory has existed since 2000, the Large and Long Program launched just last year as another means to probe the shrapnel of the big bang. It offers time on two of the world’s finest telescopes, one located atop an 8,900-foot mountain in the Chilean Andes (Gemini South) and the other on Mauna Kea, Hawaii (Gemini North).

    Gemini North telescope
    Gemini North

    Gemini South telescope
    Gemini South

    Just last month, co-leader of the Strong Lensing Science Working Group at DES, Liz Buckley-Geer, received the email she’d been waiting for: Spread over the next three years, DES had been awarded a lofty total of 276 hours on Gemini South.

    “Because we were asking for such a big block of time I really didn’t think we had much of a chance,” Buckley-Geer said. “I was pretty gobsmacked when I got the email two weeks ago.”

    With a hefty 8.1-meter mirror, the Gemini telescope is twice as large as the telescope on which DECam is currently mounted. But DES scientists don’t plan to take new images with Gemini South. DECam images are plenty clear and show high-quality snapshots of galaxies and galaxy clusters. Instead of imaging, DES scientists will use an instrument called a spectrograph to further inspect the images and, in some cases, confirm a rare phenomenon called strong lensing.

    DECam
    DECam

    One of five methods DES uses to explore dark energy, strong lensing is the bending of light from a distant galaxy, or source, due to the gravitational influence of a massive foreground object, or lens. Lensing changes the observed shape of the distant galaxy and intensifies brightness. To find these strong lensing systems in the DECam images, DES scientists look for objects that look distorted, often appearing as long bright arcs, multiple blue knots or, in the rarest cases, an Einstein ring. DES will focus on certain classes of strong lenses that can be used to study dark energy.

    “The strong lenses provide a kind of peephole to the more distant, fainter universe that wouldn’t be available if the lenses weren’t there,” said DES Operations Scientist Tom Diehl.

    But what appear to be strong lenses are not always so. To separate the lenses from the impostors, scientists measure the redshifts of both the lens and the source. A true strong lens is one in which the source redshift is larger than the lens redshift.

    A redshift occurs when light wavelengths increase, or shift toward the red side of the electromagnetic spectrum. The measured redshift of a galaxy is related to the expansion of the universe as a function of time, and it allows DES scientists to calculate the distance to the object.

    To determine the redshift of a galaxy, the scientists will compare the spectrum of the obtained light with known features in the spectrum of various chemical compounds found on Earth. If the same features are seen in an observed spectrum from a distant source but occur at shifted wavelengths, then the redshift can be calculated.

    “The observations with Gemini will give us the redshifts of all these objects, and armed with that information we can move on to the next step,” Buckley-Geer said. “It’s not all the information we need, but it’s one piece of the jigsaw puzzle closer to understanding these system in relation 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 9:25 am on April 4, 2014 Permalink | Reply
    Tags: , , , , Dark Energy Survey,   

    From Fermilab- “Frontier Science Result: Sloan Digital Sky Survey Sloan Digital Sky Survey and the cosmological constant” 


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

    Friday, April 4, 2014
    John Marriner

    The Sloan Digital Sky Survey supernova (SDSS SN) survey was born in 2004, when a team led by Fermilab’s Josh Frieman was approved as part of the first extension of the original survey. Frieman, now leader of the Dark Energy Survey, recognized that the wide-field-of-view Sloan telescope made it an ideal instrument to observe supernovae — extremely bright, exploding stars.

    The Sloan supernova project has resulted in more than 30 publications, including the recent paper of Betoule, et al, to be published in Astronomy and Astrophysics. It is the most precise analysis of supernova data to date.

    Stars in the type Ia class of supernovae explode with the same intrinsic brightness. Thus scientists can determine the distance to a supernova by measuring the apparent brightness as seen from Earth. The wavelength of distant light is shifted toward redder colors, and the amount of redshift reveals how long ago the light was emitted. Taken together, the measurements of the supernova brightness and redshift allow scientists to determine the size of the universe as a function of cosmic time.

    The Nobel Prize-winning discovery of [Saul] Perlmutter, Riess and Schmidt showed the expansion of the universe is now accelerating, not decelerating from gravity as expected. The phenomenon is called dark energy, and its properties are often described in terms of the ratio of its pressure to its density — a ratio called w. [Albert] Einstein’s equations for general relativity include the possibility of a value called the cosmological constant, which could provide the mathematical description of dark energy if the value of w is exactly -1. Any other result requires some other modification to Einstein’s equations.

    The Sloan supernova survey and a similar, higher-redshift survey known as the Supernova Legacy Survey formed a “joint lightcurve analysis” group (JLA) to analyze supernova data from both surveys. The full SDSS SN sample and essential improvements in analysis technique produced the new, precise result.

    chart
    The allowed region for cosmological parameters according the recent analysis of supernova data combined with the previously published results from the ESA/Planck satellite data.

    The figure above shows the result of the JLA analysis and illustrates the effectiveness of combining the supernova data with data from the Planck satellite, which has provided the most precise measurement of the cosmic microwave background. Along the horizontal axis, labeled ΩM, is the fraction of the universe that consists of ordinary matter, and w is the parameter that describes dark energy. The color contours show the experimentally allowed region for these cosmological parameters. The gray region shows the combination of the Planck and the JLA results.

    The measured value of w is -1.018 ± 0.057 and is consistent with Einstein’s cosmological constant. Nevertheless, it is still only a step towards understanding 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 1:14 pm on February 25, 2014 Permalink | Reply
    Tags: , , , , Dark Energy Survey, , ,   

    From Fermilab: “To catch a falling asteroid: Dark Energy Camera scientists locate object passing Earth” 


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

    Tuesday, Feb. 25, 2014
    Leah Hesla

    For seven minutes earlier this month, two Fermilab physicists moonlighted as astronomers who, like the Men in Black, were positioned to protect the Earth from the scum of the universe.

    On Feb. 3, Alex Drlica-Wagner and Steve Kent were in Chile taking data for the Dark Energy Survey when they received an email stating that a satellite telescope had picked up signs of a potentially hazardous asteroid, one whose orbit might soon meet with Earth’s.

    three
    This Dark Energy Survey observing team was on shift at the Dark Energy Camera in Chile when they got the call to check out a potentially hazardous asteroid. From left: Steve Kent (Fermilab and University of Chicago), Alex Drlica-Wagner (Fermilab) and Hernan Tirado, telescope operator at the Cerro-Tololo Inter-American Observatory, where DECam is housed. Photo: Sara Barber, University of Oklahoma

    The message had come from a scientist at the Jet Propulsion Laboratory. Bad weather in the northern hemisphere had foiled attempts by JPL’s two go-to cameras to photograph the asteroid, hindering the lab’s ability to predict its orbit. Could the Dark Energy Camera take a bit of time off from its usual task of imaging distant galaxies to take pictures of this near-Earth object?

    DECam
    DECam

    “We know about thousands of these asteroids,” said Kent, SCD. “Of course, one we didn’t know about hit Russia last year, so there’s a lot of interest.”

    Since the asteroid was new on the orbital block, astronomers had only a rough idea of where it was headed. They did know it would soon pass in line with the sun and thus be difficult to spot in photographs.

    “If we didn’t follow up on it within two days, they weren’t going to be able to follow it up anytime soon,” said Drlica-Wagner of Fermilab’s Center for Particle Astrophysics. “Because of the weather and the uncertainty of the predictions, DECam was the only thing that could pull it off.”

    Given Chile’s clear skies and DECam’s large field of view, Drlica-Wagner and Kent were fairly confident they could catch the asteroid on camera in five takes, even if its predicted location was only an estimate. They punched in the coordinates JPL gave them and took their shots. Seven minutes later, they had photos.

    The asteroid turned up in all five, though it wasn’t immediately apparent. The images had to be processed by the National Optical Astronomy Observatory in Tucson, Ariz., and coordinates submitted to the Minor Planet Center in Cambridge, Mass., to figure out the orbit. The results were then sent to JPL.

    The asteroid looked just like the faint stars that it shared the photos with, except for one characteristic — it appeared in different positions in the five images, just the way a cartoon dot would move in a flipbook.

    After combining the pictures with the satellite data, the asteroid-tracking crew brought good news.

    “People shouldn’t be particularly worried,” Drlica-Wagner said. At its closest approach to Earth on March 1, newly discovered Apollo-class asteroid 2014 BE63 will be 18 million miles away.

    The Dark Energy Camera scientists were glad to come to the aid of fellow astronomers.

    “In astronomy there are always things that are time-critical in nature. People will say, ‘You’re at the telescope. Can you do something for me?'” Kent said. “It’s a bit of a tradition to help when you can.”

    He added jokingly, “In this case, saving the Earth was an extra factor, so we thought it was generous.”

    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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