University of Minnesota
School of Physics & Astronomy


Seeing through the Cosmic Fog

Chaoyun Bao
Chaoyun Bao
Richard Anderson

Chaoyun Bao is a graduate student in professor Shaul Hanany's Observational Cosmology lab. Hanany's group launched a microwave telescope called EBEX on a balloon at high altitude from Antarctica in 2012. During the balloon's 28-day trip around the Antarctic sky it gathered data on the Cosmic Microwave Background (CMB), which is a remnant signal from the Big Bang. Bao's job is to do data analysis and simulation for EBEX, including separating polarization anisotropies from foreground contamination signal from our own Milky Way galaxy.

Bao says the group has been working on analyzing the data from the 2012 flight. The first step is to identify the usable time segments of data. Then those time segments must be aligned with the pointing data, so that the group knows what part of the sky the telescope was looking at. Then instrumental effects need to be eliminated from the data set. After all those steps, the group can create images of the sky seen by each of the thousand detectors in the telescope. With those images the group can then figure out the unknown offset between each of the balloon's detectors and finally collate all the images together to form a large observed map. Once the collation step is completed, the work of extracting cosmological signal can begin.

Bao is working on developing an algorithm to separate dust emissions produced by our own galaxy from the CMB in the collated image. She analogizes this process to trying to see through a fog. Bao's algorithm will remove galactic contamination under the presence of instrumental effects. Bao hopes that this algorithm will have broader application for other CMB experiments, since it could be adjusted and customized for various experimental settings. She is expected to graduate in 2015 ant plans to continue working in the science field.