From “Symmetry”: “15 spectacular photos from the Dark Energy Camera” Photo Essay

Symmetry Mag

From “Symmetry”

10.4.22
Lauren Biron

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The Dark Energy Survey

Dark Energy Camera [DECam] built at The DOE’s Fermi National Accelerator Laboratory.

NOIRLab National Optical Astronomy Observatory Cerro Tololo Inter-American Observatory (CL) Victor M Blanco 4m Telescope which houses the Dark-Energy-Camera – DECam at Cerro Tololo, Chile at an altitude of 7200 feet.

NOIRLabNSF NOIRLab NOAO Cerro Tololo Inter-American Observatory(CL) approximately 80 km to the East of La Serena, Chile, at an altitude of 2200 meters.

The Dark Energy Survey is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. The Dark Energy Survey began searching the Southern skies on August 31, 2013.

According to Albert Einstein’s Theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up.

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Nobel Prize in Physics for 2011 Expansion of the Universe

4 October 2011

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2011

with one half to

Saul Perlmutter
The Supernova Cosmology Project
The DOE’s Lawrence Berkeley National Laboratory and The University of California-Berkeley,

and the other half jointly to

Brian P. SchmidtThe High-z Supernova Search Team, The Australian National University, Weston Creek, Australia.

and

Adam G. Riess

The High-z Supernova Search Team,The Johns Hopkins University and The Space Telescope Science Institute, Baltimore, MD.

Written in the stars

“Some say the world will end in fire, some say in ice…” *

What will be the final destiny of the Universe? Probably it will end in ice, if we are to believe this year’s Nobel Laureates in Physics. They have studied several dozen exploding stars, called supernovae, and discovered that the Universe is expanding at an ever-accelerating rate. The discovery came as a complete surprise even to the Laureates themselves.

In 1998, cosmology was shaken at its foundations as two research teams presented their findings. Headed by Saul Perlmutter, one of the teams had set to work in 1988. Brian Schmidt headed another team, launched at the end of 1994, where Adam Riess was to play a crucial role.

The research teams raced to map the Universe by locating the most distant supernovae. More sophisticated telescopes on the ground and in space, as well as more powerful computers and new digital imaging sensors (CCD, Nobel Prize in Physics in 2009), opened the possibility in the 1990s to add more pieces to the cosmological puzzle.

The teams used a particular kind of supernova, called Type 1a supernova. It is an explosion of an old compact star that is as heavy as the Sun but as small as the Earth. A single such supernova can emit as much light as a whole galaxy. All in all, the two research teams found over 50 distant supernovae whose light was weaker than expected – this was a sign that the expansion of the Universe was accelerating. The potential pitfalls had been numerous, and the scientists found reassurance in the fact that both groups had reached the same astonishing conclusion.

For almost a century, the Universe has been known to be expanding as a consequence of the Big Bang about 14 billion years ago. However, the discovery that this expansion is accelerating is astounding. If the expansion will continue to speed up the Universe will end in ice.

The acceleration is thought to be driven by dark energy, but what that dark energy is remains an enigma – perhaps the greatest in physics today. What is known is that dark energy constitutes about three quarters of the Universe. Therefore the findings of the 2011 Nobel Laureates in Physics have helped to unveil a Universe that to a large extent is unknown to science. And everything is possible again.

*Robert Frost, Fire and Ice, 1920
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To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called Dark Energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

The Dark Energy Survey 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 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

Over six years (2013-2019), the Dark Energy Survey collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.
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Photo by Reidar Hahn, Fermilab.

The powerful camera built for the Dark Energy Survey has taken more than 1 million photos from its perch in Chile. Here are some of the best.

From high atop a mountain in the Chilean Andes, the Dark Energy Camera has snapped more than one million exposures of the southern sky. The images have captured around 2.5 billion astronomical objects, including galaxies and galaxy clusters, stars, comets, asteroids, dwarf planets, and supernovae.

Now 10 years since the Dark Energy Camera first saw stars, the impressive 570-megapixel camera was originally built at the U.S. Department of Energy’s Fermi National Accelerator Laboratory for the Dark Energy Survey. The international DES collaboration uses the deep-space data to investigate dark energy, a phenomenon that is accelerating the expansion of space.

The Dark Energy Survey, whose scientists are now analyzing the data collected from 2013-2019, isn’t the only experiment to benefit from the powerful piece of equipment. Other research groups have also used the camera to conduct additional astronomical observations and surveys. Here are some of the many stellar photos created using the Dark Energy Camera.

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Acknowledgment: M. Soraisam (University of Illinois). Image processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin CTIO/NOIRLab/DOE/NSF/AURA.

The Southern Pinwheel Galaxy (also known as Messier 83 or NGC 5236) is about 15 million lightyears from Earth. It took DECam more than 11 hours of exposure time to capture this image. The camera is mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory, a program of NSF’s NOIRLab.

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Acknowledgments: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) and D. de Martin (NSF’s NOIRLab) Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA.

The Dark Energy Survey imaged one-eighth of the sky, capturing light from galaxies up to 8 billion lightyears away. The survey repeatedly imaged 10 “deep fields” like the one shown here. By returning to certain sections of the sky, scientists are able to build up and collect different wavelengths of light to image incredibly distant galaxies and faint objects. These deep fields can be used to calibrate the rest of the DES data and to hunt for supernovae.

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Marty Murphy, Nikolay Kuropatkin, Huan Lin and Brian Yanny, Dark Energy Survey.

While the Dark Energy Survey typically looks at objects millions or billions of lightyears away, sometimes closer objects come into view. In 2014, the Dark Energy Survey spotted Comet Lovejoy traveling about 51 million miles from Earth. Each rectangle in the image represents one of the 62 CCDs that DECam uses, each one a sophisticated sensor designed to capture light from distant galaxies.

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Dark Energy Survey.

The spiral galaxy NGC 1566, sometimes called the Spanish Dancer, is about 69 million lightyears from Earth. Each photo from DECam is the result of choices made during image processing. The camera uses five filters that each record a different wavelength of light (between 400 and 1,080 nanometers) and can be combined to make color images.

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W. Clarkson (UM-Dearborn)/CTIO/NOIRLab/DOE/NSF /AURA/STScI, C. Johnson (STScI), and M. Rich (UCLA)

This DECam photo, taken looking toward the center of our Milky Way galaxy, covers an area roughly twice as wide as the full moon and contains more than 180,000 stars. You can also see a wider version encompassing more of the Milky Way’s bulge. While beautiful, the stars and dust of the Milky Way block out distant galaxies needed to study dark energy—so the Dark Energy Survey typically aims the telescope in the opposite direction, away from the plane of our galaxy.

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Erin Sheldon, Dark Energy Survey.

From our position on Earth, we see the spiral galaxy NGC 681 from the side (or edge-on). The galaxy, also known as the Little Sombrero Galaxy, is about 66.5 million lightyears away. To keep images of distant objects as sharp as possible, DECam uses a mechanism called a Hexapod, which uses six pneumatically driven pistons to align the camera’s many optical elements between exposures. In addition to the five light filters, DECam also has five optical lenses, the biggest of which is more than 3 feet wide and weighs 388 pounds.

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Image processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani and Davide de Martin
CTIO/NOIRLab/NSF/AURA/SMASH/D. Nidever (Montana State University)

This image shows a wide-angle view of the Small Magellanic Cloud. The Large and Small Magellanic Clouds are dwarf satellite galaxies to the Milky Way, and their proximity makes them a valuable place to study star formation. The Dark Energy Camera captured deep looks at our galactic neighbors for the Survey of the Magellanic Stellar History, or SMASH.

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Image processing: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), J. Miller (Gemini Observatory/NSF’s NOIRLab), M. Zamani and D. de Martin (NSF’s NOIRLab) Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA

The large galaxy at the center of this image is NGC 1515, a spiral galaxy with several neighboring galaxies in the Dorado Group. When looking at the large-scale structure of the universe, astronomers find galaxies are not distributed randomly but instead cluster together, forming a sort of cosmic web. The Dark Energy Survey has made some of the most precise maps of the universe’s structure and its evolution over time.

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Robert Gruendl, Dark Energy Survey

NGC 288 is a globular cluster of stars located about 28,700 lightyears from Earth. These stars are bound together by gravity and are concentrated toward the center of the sphere. Globular clusters are an interesting way to study how stars and our own Milky Way evolved, though the Dark Energy Survey looks at distant galaxies and galaxy clusters to better understand dark energy.

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PI: M. Soraisam (University of Illinois at Urbana-Champaign/NSF’s NOIRLab) Image processing: T.A. Rector (University of Alaska Anchorage/NSF’s NOIRLab), M. Zamani (NSF’s NOIRLab) and D. de Martin (NSF’s NOIRLab) CTIO/NOIRLab/DOE/NSF/AURA

This Dark Energy Camera image shows light from Centaurus A, a galaxy more than 12 million lightyears away. It is partially obscured by dark bands of dust caused by the collision of two galaxies.

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Image processing: DES, Jen Miller (Gemini Observatory/NSF’s NOIRLab), Travis Rector (University of Alaska Anchorage), Mahdi Zamani and Davide de Martin DES/DOE/Fermilab/NCSA and CTIO/NOIRLab/NSF/AURA

The Dark Energy Survey has found several new dwarf galaxies and used the data to limit how big potential dark matter particles could be. This irregular dwarf galaxy, IC 1613, is about 2.4 million lightyears away and contains around 100 million stars. Dwarf galaxies are considered small and faint by astronomical standards; for comparison, our Milky Way galaxy is estimated to contain between 100 and 400 billion stars.

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Rob Morgan, Dark Energy Survey

The Helix Nebula (NGC 7293) is a planetary nebula about 650 lightyears from Earth. It is shown here extending over several of the Dark Energy Camera’s CCDs. Planetary nebulae, so named because they appeared round and sharp-edged like planets, are actually the remains of stars. Here, a dying star has ejected its outer layers, leaving a small white dwarf surrounded by gas. In billions of years, our own sun will experience a similar fate.

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Dark Energy Survey

The spiral Sculptor Galaxy is about 11 million lightyears away. It’s one of more than 500 million galaxies imaged by the Dark Energy Survey across 5000 square degrees of sky. To optimize observations, DES used automated software to point the camera and capture exposures. The software could factor in what part of the sky was overhead, weather conditions, moonlight, and which areas had been recently imaged.

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Image processing: DES, Jen Miller (Gemini Observatory/NSF’s NOIRLab), Travis Rector (University of Alaska Anchorage), Mahdi Zamani and Davide de Martin DES/DOE/Fermilab/NCSA and CTIO/NOIRLab/NSF/AURA

The wispy shells around elliptical galaxy NGC 474 (center) are actually hundreds of millions of stars. To the left is a spiral galaxy, and in the background there are thousands of other, more distant galaxies—visible in this zoomable version. DECam images contain vast amounts of information; each one is about a gigabyte in size. The Dark Energy Survey would take a few hundred images per session, producing up to 2.5 terabytes of data in a single night.

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Dark Energy Survey

The Dark Energy Camera captured the barred spiral galaxy NGC 1365 in its very first photographs in 2012. The galaxy sits in the Fornax cluster, about 60 million lightyears from Earth. This close-up comes from the camera’s much wider field of view, which you can explore in the interactive DECam viewer.

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Symmetry is a joint Fermilab/SLAC publication.