Piecing the Universe together
Thanks to the work of nearly 100 astronomers from all over the world, known collectively as All-Wavelength Extended Groth Strip International Survey (AEGIS), computer users can view galaxies and star formations that date back nine billion years.
Five AEGIS teams compiled galactic images that can now be viewed on Google Sky. Marc Davis of the University of California, Berkeley and Sandra Faber of the University of California, Santa Cruz led one of these teams, called Deep Extragalactic Evolutionary Probe (DEEP2) Redshift Survey.
Jeffrey Newman, assistant professor of physics and astronomy at the University of Pittsburgh, was Davis’s “right-hand man” on the DEEP2 Redshift Survey team.
Researchers examined a strip of sky, namely the Extended Groth Strip Field, in numerous wavelengths of electromagnetic radiation, including X-rays, infrared, ultraviolet, visible, and radio waves. These various wavelengths allowed researchers to study the origin and formation of stars.
The data from these electromagnetic waves was then used to create a collection of images that can be viewed on Google Sky.
According to an ABC press release, the images feature 100 million galaxies and 200 million stars. The images allow users to view the galaxies in X-ray, ultraviolet, and infrared light.
A combination of telescopes and photographic devices made these images possible.
As stated on the AEGIS website, the equipment includes X-ray imaging in Chandra’s X-ray laboratory, the Hubble telescope and its main imaging camera, Advanced Camera for Surveys (ACS), and the Galaxy Evolution Explorer (GALEX) space telescope.
Put together, the images obtained from these instruments provide detailed pictures of the galaxies.
Newman’s team used the Keck telescopes in combination with the DEIMOS spectrograph to study galaxies.
The Keck telescopes are large telescopes used for optical and infrared astronomy, while DEIMOS is a spectroscope on the Keck telescope that photographs the spectra.
Newman said that by observing just a patch of sky, astronomers can understand that historically, evolution of the galaxies took place at a much faster rate than it does now.
Newman said, “Our survey showed that the information we used to measure distances to the galaxies can also be used to see how stars form. We noticed that the universe eight billion years ago did not look too different than what it does today; the distribution of the galaxies is quite similar to what it was after the Big Bang.”
Newman’s group was also able to detect the energy release, radiation, and future development of stars within the galaxy.
Faber, who worked with Newman in DEEP2, said that there are two fundamental parts to the mystery of the galaxies.
“Firstly, where do galaxies come from, and secondly, why do they exist?” Faber said.
Faber also said that while Hubble projects sharp and vibrant images, the images are futile on their own.
“Along with Keck, we need DEIMOS spectrograph to sort these images out in terms of distance and time. Ground-based telescopes do not produce clear images. Keck, on the other hand, is very powerful, as it is up in the atmosphere,” Faber said.
According to the AEGIS website, DEEP2 had two phases.
The first phase involved the observation of a sample of about 1000 galaxies in the Extended Groth Strip. The second phase involved using the DEIMOS spectrograph to view spectra of 50,000 galaxies up to nine billion light years away. These included 14,000 galaxies in the Extended Groth Strip.
Faber said, “The bigger the redshift, the further away the galaxy is.”
Furthermore, galaxies are typically sorted into two different classes: spheroidal and flattened disc galaxies. Spheroidal galaxies are worn out and do not produce stars, whereas flattened disc galaxies are actively producing new stellar populations.
“In the course of this research, we noticed a change in the ratio of spheroidal versus flattened disc galaxies. There appear to be many more spheroidal galaxies than flattened disc galaxies,” Faber said.
She said that, “basically, the universe is 14 billion years old, and through our technology we can see the universe as it was about nine billion years back. Thus, it is now possible, by combining all these different types of radiation in the electromagnetic spectrum, to see the universe capture the galaxies in their infancy.”