Rate of merges between galaxies studied

BALTIMORE, Oct. 27 (UPI) -- Hubble Space Telescope images and computer simulations have pinned down the rate at which smaller galaxies merge to form bigger ones, U.S. astronomers say.

The merger rate is one of the fundamental measures of galaxy evolution, yielding clues to how galaxies bulked up over time through encounters with other galaxies.

Initial deep-field surveys made by Hubble generated an imprecise range of results, suggesting 5 percent or 25 percent of the galaxies were merging, depending on how the date was analyzed, NASA said in a release Thursday.

In a study led by Jennifer Lotz of the Space Telescope Science Institute in Baltimore, a new analysis of the observations combined with supercomputer simulation of galaxy collisions yielded a much more precise estimate that falls midway between the two estimates.

"Our simulations offer a realistic picture of mergers between galaxies," she said.

"Having an accurate value for the merger rate is critical because galactic collisions may be a key process that drives galaxy assembly, rapid star formation at early times, and the accretion of gas onto central supermassive black holes at the centers of galaxies," Lotz said.