Brendan Lynch
KU News Service

Discovery of distant ‘lensing galaxy’ heralds new grasp of the universe

Thu, 10/17/2013

LAWRENCE — Occasionally, astronomers find an extraordinary “lensing galaxy” that can enhance light like a telescope from even deeper reaches of universe — brightening and magnifying background galaxies up to 30 times. 

Gregory RudnickNow, an astronomer at the University of Kansas is part of a team that has detected the most-distant-known example of a lensing galaxy — located some 9.5 billion light years away from Earth. Their findings have just been published in Astrophysical Journal Letters.

“Because it magnifies and stretches very faint background galaxies, we can see objects too intrinsically dim to otherwise observe,” said Gregory Rudnick, associate professor of physics and astronomy at KU. “The magnifying of these faint background galaxies give us opportunities to study them in unprecedented detail.”

The discovery could herald a new understanding of the way galaxies are born.

Using the Hubble Space Telescope and the Arizona-based Large Binocular Telescope Observatory, Rudnick and a team of scientists headquartered at the Max-Planck Institute in Heidelberg, Germany, have peered through the newfound gravitational lens to see a faraway galaxy forming stars at a “tremendous” rate compared to its mass in stars.

“It turns out that there are a handful of these very distant, small star-forming galaxies that are lensed by galaxies that are closer to us than the lens we have just discovered,” Rudnick said. “If you calculate the probability of this happening, it implies that these intrinsically faint, starbursting galaxies must be extremely numerous, and that they may be important building blocks of present-day galaxies.”

Moreover, the discovery allows insight into the mass and amount of dark matter in the lensing galaxy itself.

“The exact way that the light from the background galaxy is bent tells us about the amount and distribution of mass in the foreground object,” Rudnick said. “So we get an objective way of weighing the foreground object, in this case a galaxy, and seeing how its total mass is distributed — that is, how concentrated it is.”

By weighing the total mass of the lensing galaxy, and subtracting the mass of the visible stars therein, the KU researcher said that scientists could infer the mass of “dark matter” contained in the lensing galaxy. 

“Dark matter actually makes up most of the mass in the universe, but we can only infer it from a variety of techniques, of which gravitational lensing is one,” said Rudnick.  

The researchers term their discovery a “quadruple lens,” or a lens in which the source is split into four separate images.  

“Unlike a simple magnifying glass, the image isn’t just magnified and stretched,” Rudnick said. “Rather, the distribution of matter in the lens can cause strange distortions — in this case actually splitting the image into four components.”

Until the scientists can piece together the parts, the exact nature of the more distant, magnified galaxy remains opaque.

 “To ‘de-lens’ the galaxy you need a very precise understanding of the structure of the lens, which is difficult to obtain without further observations,” Rudnick said. “However, other galaxies that are similar to the lensed galaxy but were detected without being magnified by an intervening object, appear to be about a few hundred times less massive and roughly ten times smaller in spatial extent than our own galaxy. Despite their much smaller stature, these galaxies are forming new stars at rates a few times that of the much larger Milky Way. This means that they are very rapidly increasing their mass in stars.”

Wanna Skype? Chancellor gets creative to surprise Truman winner. See it here:
Rock Chalk! Junior Ashlie Koehn named KU's 18th Truman Scholar
Ashlie Koehn, a University of Kansas junior from Burns studying in Kyrgyzstan, interrupted helping her host family prepare dinner to make a Skype call on Monday evening.

.@NYTimes columnist @WCRhoden will speak at a symposium about race and sports April 23.
Wanna Skype? Chancellor gets creative to surprise Truman winner From KU News Service: Ashlie Koehn, a University of Kansas junior from Burns studying in Kyrgyzstan, interrupted helping her host family prepare dinner to make a Skype call on Monday evening. To her surprise, Chancellor Bernadette Gray-Little was on the other end of the call letting Koehn know she had been named a 2015 Harry S. Truman Scholar. Koehn is the 18th KU student to be named a Truman Scholar and the only 2015 recipient from the state of Kansas. Earlier this month, she was also named a 2015 Udall Scholar. And in spite of a distance of more than 10,800 kilometers and 11 time zones, Koehn’s thrill from hearing the news from the chancellor came through loud and clear. “Ashlie’s experience at KU epitomizes a quality undergraduate experience. She challenged herself in her coursework, exposed herself to different research opportunities, studied abroad in Germany, Switzerland and Kyrgyzstan, and participated in both student government and community service projects,” Gray-Little said. “This is quite a year for Ashlie. Her hard work is a wonderful reflection on her and also a great reflection on the university, and we all congratulate her.” Each new Truman Scholar receives up to $30,000 for graduate study. Scholars also receive priority admission and supplemental financial aid at some premier graduate institutions, leadership training, career and graduate school counseling, and special internship opportunities within the federal government. Koehn, a member of KU’s nationally recognized University Honors Program, is majoring in environmental studies, economics and international studies. Her goal after earning her KU degree is to pursue a master’s degree in economics at either the London School of Economics or the University of Reading, with a focus on the economics of climate change. In 2014, she received KU’s Newman Civic Engagement Award for her work establishing the Coalition against Slavery and Trafficking. Her involvement with the issue was sparked by Hannah Britton, associate professor of political science and women, gender, and sexuality studies, who hosted national conference on contemporary slavery at KU three years ago. “Ashlie and I met several times to think about what KU students could contribute to the issue of slavery and human trafficking, and the result was her founding of KU CAST,” Britton said. “After a year as president, Ashlie successfully handed the organization over to the next student leader. She demonstrated her strong leadership qualities by setting a unique goal and then pursuing it with her sense of passion, engagement and dedication. No matter the country or context, her leadership strength is evident in her coursework, her public service and her work experiences.” The University Honors Program works with a campus committee to select KU’s nominees for the Truman Scholarship and supports them during the application process. Anne Wallen, assistant director of national fellowships and scholarships, noted it was an amazing ruse to pull off the surprise. Originally, the call was set up to be between Wallen and Koehn. “I was totally not prepared to be greeted by Chancellor Gray-Little, but it was an amazing surprise for sure,” Koehn said. “As a first-generation student, it took time to learn the collegiate system, but my parents taught me to be resourceful and independent from a young age and KU and the Kansas Air National Guard have provided me with the opportunities to drive me into the future, both at graduate school and in my career. I plan to use the Truman Scholarship to pursue a career as an environmental economist helping to shape future trade agreements and leverage action on important international environmental issues, particularly concerning climate change.” Koehn also had a surprise of her own for the chancellor — the meal she was helping to prepare was not exactly typical Kansas dinner fare. On the menu with her host family in Kyrgyzstan on Monday was a traditional Kyrgyz meal called Beshbarmak, or “five fingers,” because you eat it with your hands. The dish is made of horse and sheep and was being prepared as a birthday celebration for Koehn’s host mom. Chancellor Gray-Little, as she signed off from Skype, made sure to encourage Koehn to enjoy her Beshbarmak. Koehn is the daughter of Rodney and Carolyn Koehn of Burns. She graduated from Fredric Remington High School in Moundridge. She is an active member of the Kansas Air National Guard and currently on leave while studying abroad in Bishkek, Kyrgyzstan. She is a member of the KU Global Scholars Program and a past member of the Student Senate. In addition to being named a 2015 Truman and Udall scholar, she was named a 2014 Boren Scholar and Gilman Scholar and in 2013 was named the Kansas Air National Guard Airman of the Year.

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