Hubble Deep Field: False Color Image
Could even fainter galaxies lie hidden in the image? To test if more galaxies might lurk in the spaces between the galaxies that Hubble finds, in this image we have removed the detected galaxies, smoothed the picture, and amplified the color scale by a factor of ten. Grey patches show where the galaxies and stars were removed. Red patches in this image correspond to variations in sky brightness that are 10 times smaller than the red patches in the first image. Statistical analysis shows that the variations of color in this image, including the new red patches, are caused mostly by noise, rather than by fainter galaxies. Therefore, Hubble has probably detected most of the light in faint galaxies.
Credit: Dr. Michael S. Vogeley - Princeton University Observatory