| Description: | Considerable attention is currently being focused on the detection of fast radio transients, spurred on by the reported detection of a 5 millisecond flash by Lorimer et al. (2007) whose time-frequency sweep would suggest a dispersion measure that places it well outside our Galaxy. I will present an update on the properties of this burst and other similar bursts detected at the Parkes radiotelescope. I will then discuss the broader problem of the detection of radio transients. I will describe the various scattering effects that potentially limit the intrinsic brightness temperatures of bright radio transients.
I then discuss how the expected detection rate of fast transients in a survey of finite sensitivity is related to the underlying properties of the population. The detection rate as a function of Galactic position is examined to identify regions that optimize survey efficiency in a survey whose field of view is limited. The impact of temporal smearing caused by scattering in the Interstellar Medium has a large and direction-dependent bearing on the detection of impulsive signals, and I present a model for the effects of scattering on the detection rate. I present formal conditions on the optimal survey strategy to adopt under different circumstances for fast transients surveys on next generation large-element, widefield arrays, such as ASKAP, LOFAR, the MWA and the SKA, and show how interstellar scattering and the finite spatial extent of a Galactic population modify the choice of optimal strategy. |
