Tune into the skies: how to do cosmology in the radio (Free Astronomy Public Lectures)

Presented by Dr Laura Wolz on Friday 23 October 2015.

Radio telescopes have made numerous appearances in media and films due to their huge, mechanical appearances contrasting with the natural background. The gigantic size of the dishes are essential for observing cosmic objects in high resolution following the basic rule: the longer the wavelength, the bigger the dish. The construction efforts are worthwhile because radio waves can pass our atmosphere nearly unobscured and thus allow us to view the Universe whether it is sunny or cloudy. But what are we looking at? Every galaxy emits a wide range of radio waves, including our own Milky Way, allowing us to measure the positions of the galaxies in space. Radio waves also carry information about the interior of galaxies, namely their hydrogen content. Radio telescopes can be used as cartographers to map the cosmic landscape by their hydrogen emission. This allows us to see areas unobtainable through visible light and take a glimpse how the Universe looked when it was less than half of its age. We can use both, galaxy catalogues and cosmic maps, to explore how the Universe evolved to the present state. We can learn how space floated apart after the Big Bang, how gravity pulls structures together and how dark energy is mysteriously speeding up the expansion of the cosmos