Finding extreme galaxies hiding in the infrared

Professor Andrew Blain

Deapartment of Physics and Astronomy

Lecture Summary

One of the last frontiers of observational astronomy is to push down the depth and coverage of observations at infrared wavelengths to match those possible at optical and radio. This is crucial, as a significant fraction of the energy produced by stars and accreting blackholes in galaxies is
absorbed by gas and dust before it can escape, and reprocessed to appear at wavelengths near 100 microns. This radiation can then be sought from instruments that are on the ground and in space; however, from the ground the challenge has been likened to trying to observe stars during the day using a telescope made of fluorescent tubes.

I will describe the progress that has been made to address this problem through the longest
accessible wavelengths - from the ground using submillimetre-wave telescopes, from the
shortest accessible wavelengths - from space using the Spitzer and WISE satellites, and
directly at the peak of their emitted power using the Herschel satellite. However, none of
these tools have the necessary angular resolution to reveal the internal structure and motion of the gas that fuels the formation of stars and fueling of supermassive blackholes that generates their power output. 

To reveal the processes within these galaxies, ALMA is being constructed in Chile. ALMA will match the Hubble Space Telescope in resolution, and allow the total power output of
galaxies to be measured directly for the first time. It will also offer the chance to see the very first objects forming in the Universe, perhaps including the assembly of the material that is destined to form and burn in the very first stars.