Baryon Acoustic Oscillations
Figure 1: Signal from Baryon Acoustic Oscillations (BAO) in the Dark Energy Survey (DES) data. When plotting the number of galaxy pairs as a function of their angular separation in the sky, we find an excess of pairs at 2.90 degrees. This is caused by BAO waves that have traveled hundreds of millions of light-years since the Big Bang. These waves subtend a size on the sky somewhat larger than predicted by the standard model of cosmology and the Planck data. Image credit: Dark Energy Survey Collaboration.