Active Galactic Nuclei

See! I promised science and here it is 🙂 Over the Christmas break, I spent some time going through old hard-drives etc, and I came across my BSc thesis from Trinity College Dublin. So I thought I’d share it with you 🙂 It is more than a little cringe-worthy (and I thought it was SO GOOD when I did it) but it might be of interest to at least a few of you, so you’ll find it here in PDF format: LW_Astrophys_TCD

At optical wavelengths, the emission from most galaxies is dominated by that from the stars. However in at least 10% of galaxies (called active galaxies), additional intense emission is also detected from the centre (nucleus) of the galaxy. This emission often far out-shines that from the surrounding stars (often by factors >102).

It turns out that Active Galactic Nuclei (AGN) are the most luminous, long-lived sources in the universe. They emit strongly over the entire observable wavelength range, from x-rays and γ- rays through to radio. The most powerful examples can radiate a thousand times as much energy as the galaxies in which they are embedded. Many AGN vary in brightness by substantial amounts over timescales as short as years, months, days, or even hours.

I looked at several of these active sources using data from three telescopes – the Hubble, the Tytler (an optical telescope actually called the Lick Observatory in San Jose) and the International Ultraviolet Explorer. I found that there was a large scatter in the data from each scope (unsurprising really!) and investigated the potential for using AGN as “standard candles

Anyway, enjoy! and please let me know if you have any questions 🙂