Amazing Discovery: Astronomers Found Large Number of Distant Dwarf Galaxies

A University of California, Riverside team of astronomers has discovered a large population of distant dwarf galaxies that belong to an important cosmic period when the universe was between two to six billion years old.

Their discovery, described in a paper published in The Astrophysical Journal, may shed some light in the productive period of star formation in the universe billion of years ago. Their findings may also provide better understanding in the history of the early universe.

According to a press release, dwarf galaxies are the smallest and dimmest galaxies in the universe. Due to their size and faintness, these galaxies remain elusive even with the most powerful telescopes we have today. In order to study these important galaxies, astronomers have been using a natural phenomenon called gravitational lensing. When a massive object such as galaxy is located along the line of sight to another object, it can act as a natural lens, making the background object to appear brighter and larger.

Using gravitational lensing and deep images of three clusters of galaxies taken by the Wide Field Camera 3 on Hubble Space Telescope, the researchers were able to detect a large population of distant dwarf galaxies that were 10 to 100 times fainter than previously observed galaxies. Spectroscopic data from Multi-Object Spectrograph for Infrared Exploration (MOSFIRE) on the W.M. Keck Observatory confirmed that the discovered galaxies were between two to six billion years old, which is considered to be the most productive time for star formation in the universe.

With their discovery, the researchers were able to demonstrate that the number of these dwarf galaxies evolves during this important time period such that they are even more abundant at earlier times. Furthermore, the researchers observed that the dwarf galaxies is responsible for more than half of the ultraviolet light during that star formation era. During those time, dwarf galaxies houses numerous of newly-formed stars, which produces ultraviolet radiation.