Low immunity to interference? • Only single beam on sky – Harder to gauge reality? • Lots of output to sift through – Much human intervention required? • There’s not much out there! – Pulsars are easier to find and study, particularly as periodic sources Discovery of RRATs in 2005 breathed new life into subject…
hr pointings = 20 days 1 ms sampling 288 MHz bandwidth 14 pulsars discovered in standard periodicity search (FFT) What about single pulses? Parkes Magellanic Cloud survey Began reprocessing data to look for dispersed pulses in Fall 2006. Motivation: look for giant-pulse-ers and RRATs
W~f-4.4 • Not a Galactic object – DM = 375 cm-3 pc • Very very unlikely to be in SMC/halo – Offset position + far higher DM • An extragalactic object – DM ~ 1200 x z implies z < 0.3 !!! – Crude estimate gives D = 500 Mpc. What is the burst’s nature?
~ 1040 erg – Brightness temperature ~1039 K • Implied event rate – 1 burst seen per 20 day with PKS – Hundreds per day over whole sky… – 0.4 per day per Gpc3 • Possible sources – GRB? NS-NS coalescence? Sne? – (PBH E~1035 erg) What is the burst’s nature?
constrain the rate • Forthcoming radio telescopes – LOFAR – ATA • Search GW data – Position and time localized…. • A new cosmological probe??? – Measurement of IGM… dark matter? Implications/predictions
to 375! • New bursts have different properties – Seen in all 13 beams – Inverted spectral properties – Inverted pulse broadening properties – No known terrestrial transmitter Cosmic conspiracy? Current working hypothesis: confidence in astrophysical origin of original burst suffered a major hit. Urgently need more examples if we are to believe this is truly astrophysical.
Probe of intergalactic medium – Electron density, Faraday rotation – Missing baryons? • New cosmological probe? – Population of standard candles? – Need to identify a counterpart! Key factors: localization and rapid alert Potential pay-offs