An international team of astronomers studied over 446,000 galaxies from the Cosmic Evolution Survey (COSMOS). The COSMOS survey was conducted over 590 orbits of the Hubble Space Telescope. During those orbits, Hubble used the Advanced Camera for Surveys (ACS) to capture 575 images of the Universe that slightly overlapped. This makes the COSMOS survey the largest survey ever conducted with Hubble.
The researchers then assigned redshift data to 194,000 of the galaxies. Redshift simply means that as an object moves away from the observer, absorption lines in the spectrum shift towards the red end of the spectrum. The more these absorption lines shift, the farther away the observed galaxy likely is. The redshift gives an estimate of distance to the galaxy. The redshift data was collected by ground-based telescopes.
With the COSMOS survey, and the assigned redshift data, the astronomers were able to independently confirm that the expansion of the Universe is accelerating. This acceleration is thought to be caused by a hypothetical form of energy called Dark Energy.
If you click through the link below, the story has four more images, and one high-definition video.
This image shows a smoothed reconstruction of the total (mostly dark) matter distribution in the COSMOS field, created from data taken by the NASA/ESA Hubble Space Telescope and ground-based telescopes. It was inferred from the weak gravitational lensing distortions that are imprinted onto the shapes of background galaxies. The colour coding indicates the distance of the foreground mass concentrations as gathered from the weak lensing effect. Structures shown in white, cyan, and green are typically closer to us than those indicated in orange and red. To improve the resolution of the map, data from galaxies both with and without redshift information were used.
The new study presents the most comprehensive analysis of data from the COSMOS survey. The researchers have, for the first time ever, used Hubble and the natural “weak lenses” in space to characterise the accelerated expansion of the Universe.
Credit: NASA, ESA, P. Simon (University of Bonn) and T. Schrabback (Leiden Observatory)
