Louis Marinho Fernandes – Time travelling through the Universe to discover and study primeval galaxies

I have just finished my second year studying Physics at University College London (UCL). Last summer, I was extremely lucky to take part in an outreach internship with the Observational Astrophysics group at Lancaster University, under the supervision of Dr Julie Wardlow. I am delighted to begin another internship this year, under the supervision of Dr David Sobral. The aim of my project is to discover and study galaxies in the early Universe. 

Because the speed of light is finite, we see stars (and therefore galaxies) in the sky as they were when their light was emitted. Hence, when looking at very distant galaxies, we actually see what they used to look like billions of years ago.  A specific area of the sky, called the COSMOS field, has been surveyed with 16 narrow-band filters to detect Lyman-α photons emitted by hydrogen from distant galaxies, which allows us to “time travel” to specific epochs of the Universe. Therefore, we can slice the Universe into different cosmic times. I will be working on SC4K, a sample of almost 4000 galaxies discovered in the COSMOS field by researchers from the XGAL group, to understand how galaxies form and what are the driving forces behind their evolution.