Targeted millisecond pulsar surveys of Fermi γ-ray sources with LOFAR

Abstract

We have used LOFAR to perform targeted millisecond pulsar surveys of Fermi γray sources. Operating at a center frequency of 135 MHz, the surveys use a novel semi-coherent dedispersion approach where coherently dedispersed trials at coarsely separated dispersion measures are incoherently dedispersed at finer steps. Three millisecond pulsars have been discovered as part of these surveys. We describe the LOFAR surveys and the properties of the newly discovered pulsars.