In the last several years, the Hubble space telescope has taken deep space photographs. This involved choosing an area of the sky not obscured by bright objects like stars or nearby galaxies, and “opening the shutter” for long periods of time to get a deep exposure.
The Hubble Ultra Deep Field (HUDF) image and the Great Observatories Origins Deep Survey ( GOODS) image were both taken using a special camera called the Advanced Camera for Surveys (ACS) that was mounted on board the Hubble in 2002. The HUDF (now dubbed the HUDF04 because it was taken in 2004) image had the shutter open for about a million seconds.
The goal of the researchers was to detect and study the most distant galaxies in these images. The HUDF04 has about 10,000 objects visible, almost all of which are galaxies, and some have been determined to be at distances corresponding to as early as 700 million years after the big bang.
Researchers have determined a number of key results:
- In the image, the objects are red because of the large amount of redshift.
- The early galaxies discovered are smaller than those nearby and bluish in color, indicating lots of star formation is going on, 10 times that of nearby galaxies.
- Evidence indicates this bluish color may provide a solution to the question of whether astronomers could account for enough ultraviolet radiation to cause the “reionization” of the interstellar material, also called the “reheating” of the universe.
- About 500 objects have ages earlier than 900 million years after the big bang.
- Much fewer, about 10%, were found having ages around 700 million years after the big bang, which is consistent with the big bang model of stars first forming about 200 to 300 million years after the big bang and then quickly collecting into small and then larger galaxies as a function of time.
In recent weeks newly taken photographs have added significantly to these earlier results. The Hubble telescope has been upgraded with a new infrared camera, the Wide Field Camera 3 (WFC3), and used to reexamine the same field contained in the earlier HUDF04 (this new observation is referred to as the HUDF09). Additionally, an international team of astronomers used the European Space Agency’s (ESA) Herschel Space Observatory to obtain deep images, also at infrared wavelengths. Observations with the Herschel telescope (reported on here and here) have yielded thousands of new galaxies at distances of 12 billion light-years.
Astronomers who have observed with the newly improved Hubble telescope (reported on here and here) claim to see galaxies as far away as 13 billion light-years, revealing objects that were shining as early as 650 million years after the big bang. A major goal in all these missions is to discover how galaxies were formed and how they evolved to give rise to present-day galaxies. In particular, astronomers are using this amazing collection of images to quantify details of galaxy formation from the earliest times, including the star-formation rates, the rate of mergers among galaxies, and the abundance of weak active galactic nuclei.
The bottom line is that these results, and those to come, will provide some of the strongest evidence in support for the big bang model and, as a consequence, for the RTB creation model for the beginning of the universe.