{"id":78221,"date":"2024-03-18T11:51:20","date_gmt":"2024-03-18T15:51:20","guid":{"rendered":"http:\/\/www.bu.edu\/cas\/?post_type=r_cas_magazine&p=78221"},"modified":"2024-03-18T16:32:46","modified_gmt":"2024-03-18T20:32:46","slug":"mapping-the-universe","status":"publish","type":"r_cas_magazine","link":"https:\/\/www.bu.edu\/cas\/arts-sciences\/article\/mapping-the-universe\/","title":{"rendered":"Mapping the Universe"},"content":{"rendered":"
By Marc Chalufour<\/h6>\n

Exploding stars. Colliding galaxies. A mountaintop camera that can see the beginning of time. These aren\u2019t plot points in the latest sci-fi series. They\u2019re the real-world building blocks of the Dark Energy Survey, a decade-long effort to map the universe and to understand what it\u2019s made of.<\/p>\n

\"Dillon
Astronomer Dillon Brout<\/figcaption><\/figure>\n

More than 400 scientists have contributed to the Dark Energy Survey (DES), including Dillon Brout<\/span><\/a>, an assistant professor of astronomy and physics. He joined the project at its outset, as a <\/span>graduate student at the University of Pennsylvania<\/span><\/a>, <\/span> and co-led the cosmological analysis team that focused on calculating the locations of supernovae, which provide clues critical to measuring the size of the universe.<\/p>\n

Cosmology is the branch of astronomy devoted to understanding the origins and nature of the universe as a whole. Like all explorers, cosmologists need a map. In the decade since DES launched, Brout and his peers have conducted the largest survey of supernovae ever, identifying approximately 1,500 of the exploding stars and using each one as a precise point in their map of the expanding universe. Their findings, submitted to The Astrophysical Journal<\/em> in January, provide an unprecedented look at the way dark energy causes that expansion to accelerate.<\/p>\n

Brout\u2019s great-granduncle\u2014the man who encouraged him to pursue cosmology\u2014was a renowned physicist who also had been drawn to the mysteries of the universe\u2019s expansion. For Brout, the DES wasn\u2019t just a professional milestone\u2014it was the continuation of a family legacy.<\/p>\n

\"The
The Cerro Tololo Inter-American Observatory, located in north central Chile, houses several telescope facilities for many kinds of astronomy, astrophysics and cosmology. PHOTOS: The Dark Energy Survey<\/span><\/figcaption><\/figure>\n

\"The<\/p>\n

The Great Unknown<\/h3>\n

There is much more that scientists don\u2019t<\/em> know about the universe than they do<\/em> know. Approximately 95 percent of the universe consists of dark matter and dark energy, opposing forces that they know must exist but can\u2019t see\u2014which is why they\u2019re \u201cdark.\u201d Figuring out how these mysterious forces shape the cosmos could explain the big bang, the explosion that created the universe nearly 14 billion years ago.<\/p>\n

\u201cEver since that initial moment of creation, the universe has been going through a tug of war,\u201d Brout says. \u201cWhat we\u2019re doing with the supernovae is using them as a measuring stick to study the interplay between the gravitational pull of dark matter inwards and the outward pressure of dark energy.\u201d<\/p>\n

The results of that battle have shaped scientific theories dating back to 1917, when Albert Einstein hypothesized that the universe was static and eternal in his general theory of relativity. To balance the inward pull of gravity of all galaxies, he believed, there must be something pushing outward in the empty space between galaxies: an \u201cenergy of empty space,\u201d that scientists call the cosmological constant. Not long after Einstein\u2019s theory, in 1929, American astronomer Edwin Hubble provided concrete evidence that the universe is not static, but rather that it is expanding and that it must have had a beginning\u2014the big bang. At the time, Einstein regarded his static universe hypothesis and his theory of the cosmological constant as the biggest blunder of his career. However, he may not have been totally wrong, says Brout. The \u201cenergy of empty space\u201d might be the dark energy that cosmologists study today, with one significant difference: it appears to be winning that eternal tug of war.<\/p>\n

To collect their data, Brout and his colleagues used a relatively basic strategy: they photographed the sky. Of course, they did so with one of the most powerful digital cameras ever made. The 570-megapixel Dark Energy Camera, mounted on a telescope at the Cerro Tololo Inter-American Observatory in the Chilean Andes, focuses on huge swaths of the sky. \u201cWe don\u2019t care about single objects or stars,\u201d Brout says. \u201cWe survey as many stars and as many galaxies as possible to collect an understanding of the entire universe and to infer what the whole<\/em> universe is doing.\u201d<\/p>\n

The researchers used a sophisticated process to analyze the images, which is where Brout made one of his biggest contributions during his PhD\u2014leading construction of the system that extracted precise measurements from the photographed supernovae. He now leads the analysis team that brought the DES \u201cfrom image pixels all the way to the fundamental properties of the universe,\u201d he says.<\/p>\n

\"The<\/p>\n

\"The
The V\u00edctor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory. PHOTOS: NOIRLab<\/figcaption><\/figure>\n

A single Supernova emits as much light as an entire galaxy of 200 billion stars, so they make ideal reference points for mapping the universe. The team was able to photograph supernovae from 500 million light years ago\u2014nearby, by cosmology standards\u2014and also discovered supernovae more than eight billion light years away. \u201cThis means that we get to see the universe as it was more than half of the way back to the big bang,\u201d says Brout.<\/p>\n

DES is the largest survey of its kind to date, and to sort through hundreds of thousands of objects, Brout relies on machine learning algorithms to help identify each supernova photographed. Then the team measured the brightness and the redshift of its light\u2014the wavelength of light moving away from us shifts to the red end of the spectrum, while light moving toward us shifts to the blue end. With that information, the DES team determined the movement of galaxies and the rate of the universe\u2019s expansion\u2014explaining how the universe works with an unprecedented level of detail.<\/p>\n

\"\"
ABOVE: An example of a supernova discovered by the Dark Energy Survey within the field covered by one of the individual detectors in the Dark Energy Camera; BELOW: The filter system installed on the Dark Energy Camera used by the Dark Energy Survey to discover supernovae and monitor their brightness evolution. PHOTO: Fermilab.<\/figcaption><\/figure>\n

\"This<\/p>\n

All in the Family<\/h3>\n

With his DES project wrapped up, Brout is looking ahead to the next major international collaboration. He\u2019s also pausing to appreciate how he ended up here\u2014because he nearly followed a different path.<\/p>\n

When Brout became interested in physics in high school, he learned a surprising fact from his parents. \u201cYou know, we have some distant relative who lives in Belgium and is apparently some important physicist,\u201d they said. \u201cI came to realize very quickly that he is one of the most important physicists of all time,\u201d Brout says.<\/p>\n

\"Robert
Theoretical physicist <\/span>Robert Brout<\/figcaption><\/figure>\n

Turns out, his great-granduncle, Robert Brout<\/span><\/a>,<\/span> along with Fran\u00e7ois Englert, published the first paper to theorize that a \u201cGod particle\u201d gives everything in the universe mass. Their theory dominated particle physics for more than half a century. Then, in 2012, scientists identified such a particle, which by then was called the Higgs boson. In 2013, Englert and Peter Higgs were awarded the Nobel Prize in physics<\/span><\/a> for their work in developing the theory; Robert Brout likely would have received the award with them, but he\u2019d died a year earlier.<\/p>\n

Dillon Brout has been researching his great-granduncle\u2019s legacy and hopes to write a book. \u201cHe\u2019s up there with Einstein because of his impact on so many different aspects of physics,\u201d he says.<\/p>\n

Brout only learned of his great-granduncle a few years before his death, but they exchanged frequent letters in that time. When Brout shared his interest in particle physics, his great-granduncle encouraged him to study cosmology instead. \u201cIn 2008, he was thinking about the birth of the universe,\u201d Brout says. \u201cThat set me on the trajectory that brought me here today.\u201d<\/p>\n

In 1978, Robert Brout \u00a0<\/span>coauthored a paper<\/span><\/a> about how the universe may have expanded in the initial moments of the big bang, a theory that is now called inflation. For Dillon Brout, working on DES and his new project is a chance to build on the idea. \u201cIf we could connect the dots between what the universe is doing now and what caused that initial inflation\u2014that would be a dream for me.\u201d<\/p>\n

With all of the progress made in 10 years of DES, Brout says, a significant breakthrough is getting closer. But mysteries still remain. Is dark energy Einstein\u2019s \u201cenergy of empty space?\u201d Or was Einstein wrong, and is there a different explanation for the nature of the universe, yet to be discovered?<\/p>\n

\"The
The Legacy Survey of Space and Time is a planned 10-year survey of the southern sky that will take place at the Vera C. Rubin Observatory, currently under construction on the El Pe\u00f1on peak of Cerro Pach\u00f3n in northern Chile. PHOTO: Stanford University.<\/figcaption><\/figure>\n

Brout is now leading a project to answer those questions: the Rubin Observatory Legacy Survey of Space and Time (LSST) Dark Energy Science Collaboration, located one mountaintop over in the Chilean Andes. The LSST will build upon the technology of DES, but with upgraded hardware, a larger field of view, and more sensitive electronics\u2014\u201cmajor improvements in every facet of building the telescope,\u201d Brout says.<\/p>\n

The DES identified 1,500 supernovae; the LSST could find 1 million. \u201cThis is revolutionary. We can ask different questions,\u201d he says. \u201cWe can probe the universe in completely new ways. It\u2019s a whole new game we\u2019re going to be playing.\u201d<\/p>\n

\"The
The Blanco Telescope. PHOTO: The Dark Energy Survey<\/span><\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

Assistant Professor of Astronomy Dillon Brout is searching for the origins of the cosmos\u2014and continuing a family legacy<\/p>\n","protected":false},"featured_media":78235,"template":"","department":[],"_links":{"self":[{"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/magazine-articles\/78221"}],"collection":[{"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/magazine-articles"}],"about":[{"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/types\/r_cas_magazine"}],"version-history":[{"count":34,"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/magazine-articles\/78221\/revisions"}],"predecessor-version":[{"id":78353,"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/magazine-articles\/78221\/revisions\/78353"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/media\/78235"}],"wp:attachment":[{"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/media?parent=78221"}],"wp:term":[{"taxonomy":"r_cas_department","embeddable":true,"href":"https:\/\/www.bu.edu\/cas\/wp-json\/wp\/v2\/department?post=78221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}