He leads an international team of astronomers which in 2015 carried out the widest survey of very distant galaxies ever attempted, with surprising results.
Using the Subaru Telescope, the 8.2-metre ESO Very Large Telescope, the 10-metre W. and the NASA/ESA Hubble Space Telescope, Sobral’s team peered billions of years back in time to find an impressive number bright galaxies, only a few hundred millions years after the Big Bang. Among them the team found COSMOS Redshift 7 (CR7), which is not only the brightest ever found in the early Universe but, even more impressively, it provides the best observational evidence that first generation of stars exist within it. This discovery is so significant that it is listed among the European Southern Observatories’ all-time top 10 astronimical discoveries.
Dr Sobral said: “My key aim is to contribute as much as I can to our understanding of how, when, why and by which mechanisms galaxies form and evolve. It is really exciting and frontier research and Lancaster University is a perfect place to really push it forward within the new Observational Astrophysics group.”
In CR7’s brightest component, Sobral and his team have so far found nothing but ionised Helium and Hydrogen, a clear prediction of the very first generation of stars (they should have been very hot and free of heavy elements), which have so far remained elusive.
Light from this early galaxy has been travelling towards us for about 12.9 billion years.
“This discovery is part of a much larger survey strategy that we are now fully implementing by exploring uncharted territory. By obtaining large and clean samples of equally selected galaxies, just after the Big Bang and right to the peak activity of the Universe (when most present-day stars where formed), we are providing a much more detailed and clearer view on how and by which physical mechanisms galaxies form, evolved, and ended up the way we see them today.”
The explosions of first generation stars created the very first heavy elements in the Universe which allowed further generations of stars and planets to form. Life itself simply would not be possible without the existence of the first stars.
More on David Sobral
- Times Higher Education magazine interview
- BBC Sky at Night podcast (interview begins after 23mins)