The most detailed dark matter map of the Universe

DES year one mass map full

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A new study from the Dark Energy Survey reveals the most accurate measurement of dark matter structure in the universe. This research uses galaxy positions and shapes to confirm that dark matter and dark energy make up most of the cosmos. Researchers from the Australian Astronomical Observatory contributed to the study with data collected at the 3.9m Anglo-Australian Telescope.

Astrophysics research has revealed that the universe in mostly made of dark matter (26%) and dark energy (70%). Atoms only account for 4% of the cosmos. The most precise measurements were derived in 2015 using data from the Planck satellite (European Space Agency) that studied the structure of the Cosmic Microwave Background (CMB), the “echo” of the Big Bang, 13.4 billion years ago.

A new study conducted by the Dark Energy Survey (DES) collaboration, an international team of scientists that includes researchers from the Australian Astronomical Observatory, supports, both qualitatively and quantitatively, that the majority of the cosmos is made up of elusive dark matter and dark energy.

The new research applies a very different approach to that used by the Planck team. DES scientists measure present-day galaxy positions and shapes to obtain the most accurate measurement ever made of the present large-scale structure of the universe.

The DES results have been made public today in a presentation at the American Physical Society Division of Particle and Fields meeting at the U.S. Department of Energy’s Fermi National Accelerator Laboratory. The analysis required 10 scientific publications to encapsulate the detail behind the final result included in the key paper released today.

The primary instrument for DES is the 570-megapixel Dark Energy Camera (DECam) mounted at the U.S. National Science Foundation’s 4m Blanco Telescope at Cerro Tololo Inter-American Observatory in Chile. This powerful camera is able to capture digital images of light from galaxies eight billion light years from Earth.

Scientists from the AAO participated in this study. AAO’s Dr Kyler Kuehn was formerly part of the US team that built DECam and has been part of the DES team since 2007.

“It is very gratifying to see these fantastic results, the culmination of more than a decade of work by hundreds of scientists and engineers to design, build, and operate the Dark Energy Camera”, Dr Kuehn said.

The AAO’s 3.9m Anglo-Australian Telescope (AAT) has played a role in the DES science results. As part of the OzDES survey, Australian astronomers used the 2dF+AAOmega facility at the AAT to measure the redshifts of thousands of galaxies imaged with DECam in the DES deep fields. These redshifts were used to help develop the techniques that were used by DES to infer the redshifts of millions of galaxies that were used to derive these results.

“The 2dF+AAOmega facility at the AAT is a perfect match to DECam. It covers the same field of view and it can obtain redshifts for almost 400 galaxies simultaneously”, AAO astronomer Dr Chris Lidman said.

Scientists on DES are using DECam to map an eighth of the sky in unprecedented detail over five years. The fifth year of observation will begin in August. The new results released today draw only from data collected during the survey’s first year, which covers one thirtieth of the sky.

“This is only the tip of the iceberg; we still have several more years’ worth of DES observations to analyse, and those should yield even more accurate cosmological measurements in due time”, Dr Kuehn emphasized.

Since 2013 Dr Kuehn has worked at the AAO as instrument scientist and astronomer. He is part of a new project, called “Taipan”, and also leads future instrumentation development. His astronomy research combines observations of dwarf galaxies around the Milky Way using both the 2dF+AAOmega instrument at the AAO’s 3.9m AAT and DECam at the 4m Blanco Telescope to seek a better understanding of the properties of the dark matter.

“In addition to the central focus of the Dark Energy Survey – for which we are now seeing the first results – there are many other scientific questions that DECam is helping to answer. Whether from the astronomers of the Dark Energy Survey itself, or other independent researchers using DECam, there will be a lot more exciting science coming out of this incredibly productive instrument”, Dr Kuehn said.

 

The AAO is a division of the Department of Industry, Innovation and Science.

The Dark Energy Survey is a collaboration of more than 400 scientists from 26 institutions in seven countries. Funding for the DES Projects has been provided by the U.S. Department of Energy Office of Science, U.S. National Science Foundation, Ministry of Science and Education of Spain, Science and Technology Facilities Council of the United Kingdom, Higher Education Funding Council for England, ETH Zurich for Switzerland, National Center for Supercomputing Applications at the University of Illinois at Urbana- Champaign, Kavli Institute of Cosmological Physics at the University of Chicago, Center for Cosmology and Astro-Particle Physics at Ohio State University, Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, 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 Ministério da Ciência e Tecnologia, Deutsche Forschungsgemeinschaft, and the collaborating institutions in the Dark Energy Survey, the list of which can be found at www.darkenergysurvey.org/collaboration.

 

Publication details:

- Link to DES webpage with the year 1 results, including links to the 10 scientific papers: https://www.darkenergysurvey.org/des-year-1-cosmology-results-papers

- Link to OzDES webpage: http://www.mso.anu.edu.au/ozdes/

- Further details about this discovery can be found on the Dark Energy Survey’s press release here: http://news.fnal.gov/2017/08/dark-energy-survey-reveals-accurate-measurement-dark-matter-structure-universe

 

Science Contacts:

- Dr Chris Lidman

Research Astronomer, OzDES Principal Investigator, Head of National Facilities, Australian Astronomical Observatory, and ARC Centre of Excellence for All-sky Astrophysics (CAASTRO)

P: +61 (0) 2 9372 4823 E: chris.lidman@aao.gov.au

- Dr Kyler Kuehn

Instrument Scientist, Australian Astronomical Observatory

M: +61 405 073 010 E: kyler.kuehn@aao.gov.au

Media contact:

- Dr Ángel López-Sánchez,

Research Astronomer and Science Communication Officer, Australian Astronomical Observatory

M: +61 406 265 917 E: angel.lopez-sanchez@aao.gov.au

Images:

DES year one mass map full

Caption: Map of dark matter made from gravitational lensing measurements of 26 million galaxies in the Dark Energy Survey. The map covers about 1/30th of the entire sky and spans several billion light years in extent. Red regions have more dark matter than average, blue regions less dark matter. Image credit: Chihway Chang of the Kavli Institute for Cosmological Physics at the University of Chicago, and the DES collaboration.

This image is available at: https://www.aao.gov.au/files/press/DES-year-one-mass-map-full.jpeg

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