And the Winning Posters Are ...

Munshi

"Correlation of Galaxy Types in the 2MASS Redshift Survey with 2MASS/SDSS Colors and HI Content," by Ferah Munshi, Karen L. Masters, and John Huchra. The authors selected 1449 bright galaxies from the 2MASS redshift survey which match with galaxies which also detected in the SDSS DR5 survey. They computed the galaxies' near-infrared and optical colors and correlate them with the galaxy type. As expected, they found variation of average color with type: later-type spiral galaxies are bluer. For a subset of 461 of these galaxies, using data on 21-centimeter emission lines from rare transitions of neutral hydrogen (HI), the authors showed that near-infrared and optical color is correlated with neutral hydrogen content. Also as expected, HI content correlates with galaxy type such that later-type spirals have a higher ratio of neutral hydrogen to luminosity. Since a galaxy's 2-micron luminosity is very well correlated with its baryonic mass in stars, this confirms the higher efficiency of star formation in early-type spirals.

Pritchard, left, and Wagner

"Lensing Magnification of High-Redshift Supernovae by Massive Clusters," by Mark Wagner, Tyler Pritchard, Kyle Dawson, Xiaosheng Huang, Saul Perlmutter, George Smoot, Nao Suzuki, and David Rubin. During the course of their most recent supernova search, the Supernova Cosmology Project discovered three high-redshift supernovae (very distant supernovae, which occurred early in the history of the universe) behind massive galaxy clusters. The clusters' gravity bends and intensifies the light from the supernovae, a phenomenon known as gravitational lensing. The authors fit theoretical models of mass, including dark matter, with the observed data from the clusters and used the resulting estimates to calculate how much gravitational lensing magnified the brightness of the supernovae, allowing excess brightness to be corrected. The goal of the project is to understand and reduce any systematic error due to weak gravitational lensing when using distant supernovae for cosmology. As increasingly distant supernovae are observed, analysis of their magnification due to gravitational lensing by foreground clusters will be of growing importance.