Fast Transient Triggering at Chilbolton

Rene Breton

Transcript

1. Fast Transient Triggering at Chilbolton LOFAR Transient KSP Meeting Amsterdam, 3 December 2012 René Breton University of Southampton & Rob Fender, Aris Karastergiou, Tim Staley et al. (Alexander van der Horst, Chris Williams, ...)
2. In the last episode...
3. A Toy Project to Develop Fast Triggering Paradigm Don’t know much about the transient radio sky Using multi-messenger information as a guide Require fast response mechanism Fast triggering Chilbolton on gamma-ray bursts detected by Swift/Fermi Develop the infrastructure Look for prompt radio emission
4. Phase 1 Full “control” of Chilbolton Interruption of current program Pre-defined observing setup Using HBA Fixed radio frequency, station configuration Hour-long follow-up Offline analysis Implementation Strategy Phase 2.1 Dynamic “control” of Chilbolton Dynamic observing setup Phase 2.2 Multi-station triggering
5. First successful trigger from Fermi GBM 38 min. observation HBA First Trigger 11 October 2012 - 12:16 Response time Improvement 6.4° off-source 60.3 sec. after the burst 34.0 sec. after the notice!
6. Phase 1 Full “control” of Chilbolton Pre-defined observing setup Hour-long follow-up Up to Now... Highlights 5 triggers so far 4 GRBs 1 X-ray binary Facility ID Type Delay GRB Delay Notice Tint Fermi 371646928 GRB 60.3 s 34 s 38 min Swift 536172 (L)-GRB 52.9 s 20 s 3 min Swift 536502 XRB 98.8 s 20 s 60 min Swift 536580 GRB 56.5 s 22 s 60 min Swift 539866 (L)-GRB 48.8 s 20 s 60 min Holy GRB, Batman! We triggered only 48.8 s after the event!
7. Phase 1 Full “control” of Chilbolton Pre-defined observing setup Hour-long follow-up Phase 2.1 Dynamic “control” of Chilbolton Dynamic observing setup Phase 2.2 Multi-station triggering Implementation Strategy Phase 2.3 Transient Buffer Board
8. Phase 2.1 Dynamic “control” of Chilbolton Dynamic observing setup Improving the Observing Strategy Fermi’s initial position uncertain by several degrees Relatively poor (~10°) Fermi’s initial localization Further notices to refine position Possible concurrent Swift alert
9. Phase 1 Full “control” of Chilbolton Pre-defined observing setup Hour-long follow-up Phase 2.1 Dynamic “control” of Chilbolton Dynamic observing setup Phase 2.2 Multi-station triggering Implementation Strategy Phase 2.3 Transient Buffer Board
10. Phase 2.2 Multi-station triggering Improving the Analysis Strategy RFIs are our worst enemy Analysis pipeline currently being written: Periodicity search Single pulse search Think Bannister et al. 2012... 8 Bannister et. al.
11. Phase 2.2 Multi-station triggering Improving the Analysis Strategy Analysis pipeline currently being written: Periodicity search Single pulse search 10 Bannister et 101 A s seed poo deri dur W dom puls the all ther to r Im it o usu to h Imp RFI ofte the in t the T high orig puls puls to a high DM T Bannister et al. 2012
12. Phase 2.2 Multi-station triggering Improving the Analysis Strategy RFIs are our worst enemy Analysis pipeline currently being written: Periodicity search Single pulse search Preliminary data analysis of the first Chilbolton trigger
13. Phase 2.2 Multi-station triggering Improving the Analysis Strategy RFIs are our worst enemy Anti-coincidence observation Credit: A. Karastergiou
14. Phase 2.2 Multi-station triggering Improving the Analysis Strategy RFIs are our worst enemy Anti-coincidence observation Terrestrial RFI pulsar dispersed transient? Credit: A. Karastergiou
15. Phase 1 Full “control” of Chilbolton Pre-defined observing setup Hour-long follow-up Phase 2.1 Dynamic “control” of Chilbolton Dynamic observing setup Phase 2.2 Multi-station triggering Implementation Strategy Phase 2.3 Transient Buffer Board
16. Gamma-Ray Bursts... Phase 3 Add Transient Buffer Board Dispersion delay helps catching up with the burst At 150 MHz, simultaneous with GRB if DM > 265 for 48.8 s delay after burst 184 ms/DM @ 150 MHz 1660 ms/DM @ 50 MHz Theory perspective “True” prompt emission (Macquart 2007) Precursor emission (Hansen & Lyutikov 2001) y e 0:1 D 100 Mpc  22 B2=3 15 a25=2 7 : …6† n the range of the larger radio telescopes operating gh somewhat less than the sensitivities of current nt searches. everal complications that may preclude generation of on. If the neutron star is moving through a pre- ma generated by the previous orbital cycles the may be quenched, there will be no need to accelerate les and the beam luminosity may drop to zero. In formation of positronium in the magnetic fields 4  1012 G (Usov & Melrose 1996; Arons 1998) may the radio emission. re, the generated radio emission may be absorbed in rsphere. We expect that non-resonant Thomson the low frequency …n ! nB † radio emission will not because of the strong suppression ‰s ˆ sT …n=nB †2Š ering cross-section by the magnetic field at low PAI R P LAS M A Most of the energy liberated by the strong electric fields of Section 2 is not radiated, but is instead released into the magnetosphere of the slowly rotating magnetar in the form of Alfve Ân waves and a dense pair plasma. The energy release (see equation 5) is a significant fraction of the local magnetic energy density. In such a case, a wind, driven either by hydromagnetic or plasma pressure is likely to result (Paczynski 1986, 1990; Melia & Fatuzzo 1995; Katz 1996) while some will remain trapped, in a fashion similar to that of the Soft Gamma Repeater picture of a magnetically confined pair plasma (Thompson & Duncan 1995). We envisage that the plasma released into regions of decreasing field strength powers the wind while plasma released into regions of increasing field strength will be trapped. Fig. 1 shows a schematic version of our scenario. Let us consider first the case of the wind. A release of energy at the rate given by equation (5) results in a compactness parameter h ˆ L=ac , 107B2 15 a27 : Thus, this is the same situation envisaged in cosmological models for gamma-ray bursts (Goodman 1986; ematic version of the energy extraction process. The motion of the companion through the magnetar field induces a plasma flow from the o the magnetosphere. The pressure of this flow will drive a relativistic wind in those regions where the flow moves into a regime of weaker plasma remains trapped in the case when it flows into a stronger field regime. The hot pair plasma will ablate some baryons off the surface of r, providing a baryon-loaded sheath which regulates the cooling of the trapped plasma. MNRAS 322, 695±701 Hansen & Lyutikov 2003 Motivation to use the TBB
17. In the next episode... So far 5 successful triggers at Chilbolton “Record”: 48.8 s delay after burst (20 s turnaround time from notice) Coming up Data analysis pipeline Improved observing control Anti-coincidence observation Detection of GRB prompt radio emission?
18. See