LOFAR radio search for single and periodic pulses from M 31

Bright short radio bursts are emitted by sources at a wide range of distances: from the nearby Crab pulsar to remote fast radio bursts (FRBs). FRBs are likely to originate from distant neutron stars, but our knowledge of the radio pulsar population has been limited to the Galaxy and the Magellanic Clouds. In an attempt to increase our understanding of extragalactic pulsar populations and their giant-pulse emission, we employed the low-frequency radio telescope LOFAR to search the Andromeda galaxy (M 31) for radio bursts emitted by young Crab-like pulsars. For direct comparison we also present a LOFAR study on the low-frequency giant pulses from the Crab pulsar; their fluence distribution follows a power law with slope 3.04 ± 0.03. A number of candidate signals were detected from M 31, but none proved persistent. FRBs are sometimes thought of as Crab-like pulsars with exceedingly bright giant pulses; based on our sensitivity, we can rule out that M 31 hosts pulsars that are more than an order of magnitude brighter than the Crab pulsar if their pulse scattering follows that of the known FRBs.