Astronomers create first-ever dark matter map

Chuck Bednar for – @BednarChuck

After two years worth of work by some 300 researchers, the Dark Energy Survey (DES) project have unveiled the first in a series of dark matter maps showing the distribution of the mysterious substance experts believe makes up roughly 27 percent of the universe.

According to BBC News, the maps show how conglomerations of dark matter change over time and was created using a 570-megapixel camera attached to the Victor Blanco telescope in Chile. The research was presented Tuesday at a meeting of the American Physical Society, and the DES team has uploaded a paper detailing their findings to the arXiv pre-publication server.

A work in progress

The current maps depict just 0.4 percent of the sky, but astronomers eventually plan to map dark matter in one-eighth of the universe, according to BBC News. The researchers are calling them the largest contiguous maps created at this level of detail, and believe that they will improve our understanding of dark matter’s role in the formation of galaxies.

“Our goal all this time has been to see the invisible – to see dark matter,” Sarah Bridle, co-chair of the DES weak lensing group that produced the map as well as an astrophysics professor at the University of Manchester, told the British news agency. “To be able to look at a map and say, ‘That part of the sky’s got more dark matter in it, that bit’s empty,’ is the dream that we’ve had all this time, [and] it’s been a long time coming.”

Since it does not emit or block light, dark matter cannot be detected by even the most sensitive instruments. However, its effects can be observed by using gravitational lensing, a phenomenon that takes place when a gravitational pull of dark matter bends light around distant galaxies. By analyzing the role of dark matter, scientists are hoping to learn more about dark energy’s role in the acceleration of the universe’s expansion.

No surprises so far

Over much of the past two years, DES team members have worked to ensure that their system worked as planned, as well as reviewing the massive amounts of data it collected. The scientists measured the shapes of millions of galaxies during its initial survey, Engadget explained. Some of that analysis involved mitigating additional lensing effects caused by the Earth’s atmosphere and imperfections with the telescope itself.

“We measured the barely perceptible distortions in the shapes of about 2 million galaxies to construct these new maps,” said co-lead investigator Vinu Vikram from the Argonne National Laboratory and formerly form the University of Pennsylvania. “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 current maps cover only approximately three percent of the area of sky that the DES plans to document over the course of its five-year mission, and the organization said that has that mission expands, the scientists hope to compare the amounts of dark and visible matter in order to better test current cosmological theories claiming that the abundance of dark matter and the strength of its gravity suggests that galaxies will form in areas of high dark matter concentration.

“Our analysis so far is in line with what the current picture of the universe predicts,” said study co-author and ETH Zurich researcher Chihway Chang. “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.”


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