An expert on galaxy formation and evolution, the physics of the interstellar medium, plasma diagnostics and spectral synthesis, star formation and the feeding and the galactic environment of black holes, he is author of over 630 publications (360 refereed) and invited speaker at over 50 conferences. His research work has been cited over 21000 times, and his H-Index is 75. In 2002, with his long-time colleague Ralph Sutherland, he published a major text book in the field, Diffuse Matter in the Universe. He is ISI Citation Laureate (2001), was awarded the Australian Centenary Medal (2003), Member of the Order of Australia (AM) (2013) and an inaugural Australian Federation Fellow (2002-06). He was Editor-in-Chief for Astrophysics & Space Science (2007-14). He has either served upon or chaired a number of HST and Spitzer Space Observatory peer review panels and international visiting committees.