In 2008,a massive cluster of yellowish galaxies appears to have been caught in a spider web of eerily distorted background galaxies, in an image taken by the Advanced Camera for Surveys (ACS) aboard NASA’s Hubble Space Telescope. The gravity of the cluster’s trillion stars functions as a cosmic “zoom lens,” bending and magnifying the light of the galaxies far behind it, a technique known as gravitational lensing.
The faraway galaxies appear as arc-shaped objects around the cluster, named Abell 1689. The increased magnification provided by the lens allows astronomers to study extremely distant galaxies in greater detail.
One galaxy, dubbed A1689-zD1, is so far away that it does not show up in the visible-light image taken with ACS. However, its light is stretched to invisible infrared wavelengths by the universe’s expansion. To observe this remote galaxy, astronomers used both Hubble’s Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and NASA’s Spitzer Space Telescope with its Infrared Array Camera (IRAC).
The distant galaxy appears as a grayish-white smudge in the close-up view taken with Hubble’s NICMOS, and as a whitish blob in the Spitzer IRAC close-up view. The galaxy is teeming with star birth. Astronomers estimate that the galaxy is 12.8 billion light-years away. Abell 1689 is 2.2 billion light-years away.
A1689-zD1 was born during the middle of the “dark ages” – a period in the early universe when the first stars and galaxies were only beginning to burst to life – which lasted from about 400,000 to roughly one billion years after the Big Bang. Astronomers believe that A1689-zD1 was one of the galaxies that helped end this period of darkness.
Thanks to advanced telescopes such as Hubble and Spitzer, astronomers are able to explore and discover even the most remote galaxies in our universe. This newly identified A1689-zD1 provides an exciting opportunity to uncover more details about our universe’s history and uncover secrets which may have been hidden for eons.