Pulsars, transients and relativistic astrophysics

Abstract:

At least half the radio galaxies at z > 1 in the 7C Redshift Survey have extremely red colours (R - K > 5), consistent with stellar populations which formed at high redshift (z greater than or similar to 5). We discuss the implications of this for the evolution of massive galaxies in general and for the fraction of near-IR-selected EROs which host AGN, a result which is now being tested by deep, hard X-ray surveys. The conclusion is that many massive galaxies undergo at least two active phases: one at z similar to 5 when the black hole and stellar bulge formed and another at z similar to 1 - 2 when activity is triggered by an event such as an interaction or merger.