Tag archives: BOSS

An artist’s illustration of how BOSS uses quasars to measure the distant universe. (Courtesy: Zosia Rostomian, Lawrence Berkeley National Laboratory; Andreu Font-Ribera, BOSS)

By Calla Cofield at the APS April Meeting in Savannah, Georgia

Scientists looking at data from the Baryon Oscillation Spectroscopic Survey (BOSS), the largest programme in the third Sloan Digital Sky Survey, have measured the expansion rate of the universe 10.8 billion years ago — a time prior to the onset of accelerated expansion caused by dark energy. The measurement is also the most precise measurement of a universal expansion rate ever made, with only 2% uncertainty. The results were announced at a press conference at the APS’s April meeting on Monday, at the same time that the results were posted on the arXiv preprint server.

The rate of universal expansion has changed over the course of the universe’s lifetime. It is believed to have gradually slowed down after the Big Bang, but mysteriously began accelerating again about 7 billion years ago (by rippstein). BOSS and other observatories have previously measured expansion rates going back 6 billion years.

(more…)