By combining the power of the cosmic “natural lens” with the capabilities of the NASA’s Hubble Space Telescope, astronomers made a surprising discovery – the first example of a compact but massive, rapidly rotating disc galaxy in which star formation ceased only a few billion years after the Big Bang.
When the Hubble took a picture of this galaxy, astronomers expected to see a chaotic star-filled region in the shape of a ball formed as a result of the unification of several galaxies, and instead found a compact, neat disk (on the right in the photo).
These observations were the first direct observational confirmation that at least some of these early so-called “dead” galaxies – in which star formation ceased – somehow evolved from disk galaxies to giant elliptical galaxies that we see today.
“This research can turn our perception of how certain elliptical galaxies form in the universe,” said research leader Sune Toft from the Dark Cosmology Center of the Institute. Niels Bohr of Copenhagen University, Denmark. “Perhaps we could not understand earlier that the early” dead “galaxies were disk galaxies, because we could not distinguish their shape from the images.”
In his study, Toft and his colleagues used the phenomenon known as gravitational lensing, thanks to which it became possible to determine that the observed galaxy has a disk, rather than an ellipsoidal shape.