Cosmological Applications of Pulsars: Fast Radio Bursts and Pulsar Timing Arrays

Pulsars (and pulsar-like emission) can potentially be used to study the composition and evolution of the Universe, through characterisation of fast radio bursts, and searches for cosmological gravitational waves. Fast radio bursts (FRBs) are highly dispersed pulses of coherent radio emission, apparently originating at Gpc distances. In the first part of the talk I will discuss the (improbable) real-time discovery of FRB 131104 in the direction of the nearby Carina dwarf-spheroidal galaxy, present subsequent follow-up observations, and speculate on the origins of FRBs. Nanohertz-frequency gravitational radiation can be potentially detected through timing observations of millisecond pulsars. In the second part of the talk, I will present a new limit on the amplitude of the stochastic gravitational-wave background and discuss how it challenges our understanding of the formation and evolution of supermassive black holes and their host galaxies.