Abell 2218 Reveals More Cosmic Secrets
Galaxy Clusters are some of the most enigmatic and beautiful phenomenon observable. They are also often home to another fascinating occurence known as gravitational lensing. One which I have imaged many times over is Abell 2218. Located in Draco (a great constellation for deep sky galaxy hunting), this cluster is well known for an image from hubble showing massive arcs of distorted galaxies. The light from these galaxies passes near the cluster and gravity bends and warps the light creating interesting arcs, swirls and swooshes.
Today, it was announced that this lensing effect has enabled astronomers to identify the most distant galaxy ever discovered. At a mere 500 million years old “after the big bang”, this heavily red-shifted galaxy is the most distant known. We probably will need to wait for a new round of infrared optimized telescopes to observe further back.
By Hubble’s Law, the more distant the object, the faster the object is receding from us. As with the doppler effect, objects moving away from us have their light shift towards the longer end of the spectrum, or towards being more “red”. However, specialized mirrors and cameras need be deployed to maximize the collection of this infrared light.
A few weeks ago I received a new telescope (about which more later ) and one of my first light tests was to hit this same target, Abell 2218. Here’s the comparison of my image with that from hubble. While it may not appear very interesting, what is interesting is that there is a clear presence of “gravitational arc L” in this image. At lower than magnitude 23, this is an impressive feat for the front driveway of a “rural” Seattle home!