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ASU astronomers find young galaxies that appeared soon after the Big Bang

July 25, 2017

Using powerful Dark Energy Camera in Chile, researchers reach the cosmic dawn

ASU astronomers Sangeeta Malhotra and James Rhoads, working with international teams in Chile and China, have discovered 23 young galaxies, seen as they were 800 million years after the Big Bang. The results from this sample have been recently published in the Astrophysical Journal.

Long ago, about 300,000 years after the beginning of the universe (the Big Bang), the universe was dark. There were no stars or galaxies, and the universe was filled with neutral hydrogen gas. In the next half-billion years or so, the first galaxies and stars appeared. Their energetic radiation ionized their surroundings, illuminating and transforming the universe.

This dramatic transformation, known as re-ionization, occurred sometime in the interval between 300 million years and 1 billion years after the Big Bang. Astronomers are trying to pinpoint this milestone more precisely, and the galaxies found in this study help in this determination.

“Before re-ionization, these galaxies were very hard to see, because their light is scattered by gas between galaxies, like a car’s headlights in fog,” Malhotra said. “As enough galaxies turn on and ‘burn off the fog’ they become easier to see. By doing so, they help provide a diagnostic to see how much of the ‘fog’ remains at any time in the early universe.

Milestones in the history of the universe
Milestones in the history of the Universe (not to scale). The intergalactic gas was in a neutral state from about 300,000 years after the Big Bang until light from the first generation of stars and galaxies began to ionize it. The gas was completely ionized after 1 billion years. The LAGER study takes a close look at the state of the Universe at 800 million years (yellow box) to investigate when and how this transformation occurred. Image courtesy of National Astronomical Observatory of Japan

The Dark Energy Camera

To detect these galaxies, Malhotra and Rhoads have been using the Dark Energy Camera (DECam), one of the new powerful instruments in the astronomy field. DECam is installed at the National Optical Astronomy Observatory (NOAO)’s 4-meter Blanco Telescope, located at the Cerro Tololo Inter-American Observatory (CTIO), in northern Chile, at an altitude of 7,200 feet.

“Several years ago, we carried out a similar study using a 64-megapixel camera that covers the same amount of sky as the full moon,” Rhoads said. “DECam, by comparison, is a 570-megapixel camera and covers 15 times the area of the full moon in a single image.”

DECam was recently made even more powerful when it was equipped with a special narrowband filter, designed at ASU’s School of Earth and Space Exploration (SESE), primarily by Rhoads and Zhenya Zheng (who was a SESE postdoctoral fellow and is currently at the Shanghai Astronomical Observatory in China), with assistance from Alistair Walker of NOAO.

“We spent several months refining the design of the filter profile, optimizing the design to get maximum sensitivity in our search,” said Zheng, the lead author of this study.

Touching the cosmic dawn

The galaxy search using the ASU-designed filter and DECam is part of the ongoing “Lyman Alpha Galaxies in the Epoch of Reionization” project (LAGER). It is the largest uniformly selected sample that goes far enough back in the history of the universe to reach cosmic dawn.

“The combination of large survey size and sensitivity of this survey enables us to study galaxies that are common but faint, as well as those that are bright but rare, at this early stage in the universe,” said Malhotra.

Junxian Wang, a co-author on this study and the lead of the Chinese LAGER team, adds that “our findings in this survey imply that a large fraction of the first galaxies that ionized and illuminated the universe formed early, less than 800 million years after the Big Bang.”

The next steps for the team will be to build on these results. They plan to continue to search for distant star-forming galaxies over a larger volume of the universe and to further investigate the nature of some of the first galaxies in the universe.  

Top photo: CTIO Blanco Telescope in Chile. Photo by Tim Abbott/CTIO

Karin Valentine

Media Relations & Marketing manager , School of Earth and Space Exploration

480-965-9345

 
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Young African leaders learn about successes, challenges of solving problems in America

Young African leaders find innovation during fellowship at ASU.
July 25, 2017

ASU hosts 50 Mandela Fellows in 6-week State Department program

A group of young African leaders has been visiting Arizona to learn how American institutions collaborate to solve problems — and also how sometimes they fail.

Arizona State University is among several universities that are hosting the Mandela Washington Fellowship for Young African Leaders, an intensive six-week program of academic work and community service. This is the fourth year of the fellowship program, begun in 2014 as the main part of the Young African Leaders Initiative in the U.S. Department of State. The 50 fellows at ASU are from 28 countries in Africa and are in one of two study cohorts: civic leadership and public management.

“It’s eye-opening for them to see the continuing issues we’re dealing with in the U.S.,” according to Alberto Olivas, the academic director for the civic leadership group. Olivas is executive director of the Congressman Ed Pastor Center for Politics and Public Service in the College of Public Service and Community Solutions at ASU, which is hosting the program.

“A lot of them are surprised that we’re as frank as we are about the challenges we’re still dealing with in terms of racism. Homelessness as an issue has been very surprising for them,” he said.

“It’s good for them to see that not everything is perfect in America, but here’s what we’re working on and here’s what we’ve learned so far in confronting these issues of race and class and historical conflicts,” Olivas said.

The fellows are between the ages of 25 and 35 and are selected based on their accomplishments in their home countries. Many own their own businesses, lead nonprofit organizations or teach. While here, each scholar develops a project that he or she can implement back in the home community. They also learn practical skills, such as marketing strategies and the best way to write a grant application.

Video by Deanna Dent/ASU Now

Labran Alio Maidoukia is a fire captain in charge of security at a uranium processing plant in Niger, a French-speaking country in west Africa.

“Uranium is like our bank account. So I’m in charge of the safety of our bank account,” he said.

Maidoukia was hired by the United Nations to work with other countries in Africa on developing a response plan for terrorist attacks.

“I am a fire captain, so I don’t have public management and policy skills. That’s what I’m looking for here,” he said.

The fellows are meeting with several community organizations including the Tucson Urban League, Ability 360 and Native American Connections.

“The Tucson Urban League CEO was very frank and open with them about the struggles the organization has had and her efforts to turn around the organization to be on more solid footing,” Olivas said. “It was very practical for them, and they asked a lot of questions.”

The fellows have also had fun. The group has visited the Grand Canyon, Kartchner Caverns, the Musical Instrument Museum and an adventure course in Flagstaff.

Shaakira Chohan, who is an architect in Johannesburg, South Africa, said the rope course taught her a lesson about leadership.

“I’m an active person, and I like the outdoors. I took it for granted that it was something everyone would be excited to do,” she said. “Then I saw firsthand that some people were genuinely scared. So instead of moving quickly through the course, I realized that it was a role I could play to help people use their bodies to move forward, so it became about teamwork.”

The brutal summer heat has been challenging for some of the scholars. Chohan said that as an architect, she was surprised by Phoenix.

“It’s a desert climate but yet as I walk around the city, I haven’t seen a particularly responsive design, with elements like shading. Why is there so much tarmac?” she said.

“I’m looking to learn how we increase effective community participation in our design so it doesn’t happen from the top down but is reflective of the culture.” 

Olivas said that he has had to gather a lot of local expertise in his role as academic director.

“It’s been a rediscovery of how rich this community is in expertise and talent and heart, and it’s been an opportunity to create new networks of mutual support within ASU and local institutions,” he said.

“And having the Mandela program here gives our community leaders an opportunity to have a global impact by sharing what they know.”

Top photo: Simphiwe Petunia Dube, a Mandela fellow from Swaziland, makes her way across a ropes course during a leadership training exercise at Flagstaff Extreme Adventure Course on June 26. Photo by Deanna Dent/ASU Now

Mary Beth Faller

reporter , ASU Now

480-727-4503