A very small, faint galaxy more than 13.4 billion light-years from Earth is creating a
great deal of excitement among astronomers. This protogalaxy, which is just 500
light-years across (a two-hundredth of the size of the Milky Way), is thought to be
one of the building blocks of today’s galaxies. It may prove to be an important
missing piece in the puzzle of how and when the first stars and galaxies formed in the
universe.
The discovery was made thanks to the gravitational lensing of light
from the distant protogalaxy by a huge cluster of galaxies along the line of sight. The
cluster effectively magnified the light from the protogalaxy.
The protogalaxy
was first identified from images taken from the Hubble Space Telescope archive, and
further observations of its spectrum were made using the two 10 m Keck telescopes in
Hawaii. The observations reveal a 2 million year old, 1 million solar mass,
galaxy-like object consisting of young hot stars.
Previous galaxies discovered
at high redshifts are extremely bright. This is the first time that a faint protogalaxy
has been analysed, owing to the amplification of its signal by the gravitational lens.
