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Results of automatic, high time resolution GRB follow-up with t he Parkes 12 m

Results of automatic, high time resolution GRB follow-up with t he Parkes 12 m. Keith Bannister k.bannister@physics.usyd.edu.au Sydney Institute for Astronomy (SIfA) University of Sydney CSIRO Astronomy and Space Science CAASTRO. Thanks To: CASS : John Reynolds , Chris Phillips,

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Results of automatic, high time resolution GRB follow-up with t he Parkes 12 m

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  1. Results of automatic, high time resolution GRB follow-up with theParkes 12 m Keith Bannister k.bannister@physics.usyd.edu.auSydney Institute for Astronomy (SIfA) University of Sydney CSIRO Astronomy and Space Science CAASTRO • Thanks To: • CASS: John Reynolds , Chris Phillips, • Sarah Burke-Spolaor, Mike Keith • Swinburne: Willem van Straten, Andrew Jameson, • Matthew Bailes • HTRU Team • Supervised By: • Tara Murphy (USyd) • Bryan Gaensler (USyd) • Tim Cornwell (CASS)

  2. Gamma ray bursts Gamma rays Long GRB (>2s) Collapse of massive star, or Short GRB (< 2s) Binary merger ? Parkes 12m Coordinates Internet Gamma Ray Coordinate Network (GCN)

  3. Robotic follow-up • Automatically slew the 12m to the GRB coordinate • On source within 2 minutes • 1.4 GHz, 250 MHz bandwidth • 64us time resolution, 600 channels • Searched for: • Single pulses • Repeating pulses (e.g. pulsars) • Long time scale (>1s) variation

  4. Bucket Feed

  5. Installation

  6. Results • Responded to 15 GCN events • 9 GRBs • Remainder where X-ray binaries or instrumental effects • Two single pulse detections • One repeating candidate • probable high latitude pulsar • Nothing in long time resolution

  7. Single pulse detection GRB 101011A 6.6 σ pulse (~7 Jy), 25 ms wide, 524s after GRB 101011A

  8. Single pulse detection GRB 100704A 6.2 σ pulse (~7 Jy), 6 ms wide, 1076 s after GRB 100704A

  9. Correspondence with X-ray break GRB 101011A

  10. Correspondence with X-ray break - 2

  11. Keith Bannister Rates • 2/9 GRBs have a single pulse detection • 2/7 long GRBs have a single pulse detection • Blind rate = 3.5 x 105 sky-1 day-1 at ~7 Jy • GRB rate (2 sky-1 day-1) is compatible with ATA fly’s eye result (Simeon et. al. 2011) of < 24 sky-1 day-1at ~44 Jy

  12. Are they real? • Could it be random chance? • Statistical argument rules out with > 99.8% confidence • Null test rules out random pulse with 99% confidence • Rate incompatible with chance detection of all other known astrophysical sources • 20% chance of random event falling on X-ray break • Equipment bug • Just an unlucky bit of RFI junksbronews.com Keith Bannister

  13. Conclusions Delayed GRB radio pulses Delayed formation of a black hole after magnetar spindown? Applications: direct detection of the intergalactic medium, distinguishing between reionisation models GRB physics • Good things can be done with a small telescope • Typically on source within 2 minutes • Possible high latitude pulsar detected serendipitously • Next: confirm with coincidence or interferometer experiment

  14. A shameless plug Two new techniques for antenna-coherent detection of dispersed radio pulses: The Chirpolator & The Chimageator 2011 ApJS,196 16B

  15. Chirpolator: de-disperse thyself frequency x1(t) x2(t) B time Δt T Y(f) frequency y(t)=x1(t) x2*(t) FFT(y(t)) y(t) time frequency

  16. Computational Costs Pre integrator Post integrator Keith Bannister

  17. Keith Bannister Data Rates

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