1. Results of automatic, high time resolution GRB follow-up with the 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 Supervised By: Tara Murphy (USyd) Bryan Gaensler (USyd) Tim Cornwell (CASS) Thanks To: CASS: John Reynolds, Chris Phillips, Sarah Burke-Spolaor, Mike Keith Swinburne: Willem van Straten, Andrew Jameson, Matthew Bailes HTRU Team

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

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 2

4. Bucket Feed 3

5. Installation 4

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 5

7. Single pulse detection 6 6.6 σ pulse (~7 Jy), 25 ms wide, 524s after GRB 101011A GRB 101011A

8. 7

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

10. Correspondence with X-ray break 9 GRB 101011A

11. Correspondence with X-ray break - 2 10

12. Rates ›2/9 GRBs have a single pulse detection ›2/7 long GRBs have a single pulse detection ›Blind rate = 3.5 x 10 5 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 -1 at ~44 Jy Keith Bannister11

13. 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 Keith Bannister12 junksbronews.com

14. Conclusions ›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 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 13

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

16. Chirpolator: de-disperse thyself 15 y(t)=x 1 (t) x 2 * (t) time frequency y(t) FFT(y(t)) frequency Y(f) time frequency Δt x 1 (t) B T x 2 (t)

17. Computational Costs Pre integratorPost integrator Keith Bannister16

18. Data Rates Keith Bannister17