Science Forums 2

[CraigD]

Originally Posted by Pluto

Lenses galore - Hubble finds large sample of very distant galaxies

Galaxy clusters of galaxies are big, very big and I'd like someone to explain to me how they could be formed in just 700 million years. I know I keep on repeating myself. But! the answer or explanation is what I'm seeking. A scientific explanation.

Pluto, I believe you misunderstand the survey the news article you’ve linked describes.

The very distant (redshift z>7) galaxies reported are not part of the galaxy clusters used as gravitational lenses to image them. These galaxy clusters – 6 were used, including Abell 2218, are fairly nearby, about 2 billion light years away.

Detail of the study can be found in a paper linked to from the news article, “A Hubble & Spitzer Space Telescope Survey for Gravitationally-Lensed Galaxies: Further Evidence for a Significant Population of Low Luminosity Galaxies beyond Redshift Seven” (warning – 6.5 MB PDF file). The wikipedia article “gravitational lens” has an introductory explanation of how clusters of galaxies are used as gravitational lenses to make very distant observations, and references to more detailed explanations.