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Fast Transient Triggering at Chilbolton

transientskp
December 03, 2012

Fast Transient Triggering at Chilbolton

Rene Breton

transientskp

December 03, 2012
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  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, ...)

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  2. In the last episode...

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  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

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  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

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  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!

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  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!

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  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

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  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

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  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

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  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.

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  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

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  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

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  13. Phase 2.2
    Multi-station triggering
    Improving the Analysis Strategy
    RFIs are our worst enemy
    Anti-coincidence observation
    Credit: A. Karastergiou

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  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

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  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

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  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 Â 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

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  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?

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  18. See

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