results of automatic, high time resolution grb follow-up with t he parkes 12 m
DESCRIPTION
Results of automatic, high time resolution GRB follow-up with t he Parkes 12 m. Keith Bannister [email protected] Sydney Institute for Astronomy (SIfA) University of Sydney CSIRO Astronomy and Space Science CAASTRO. Thanks To: CASS : John Reynolds , Chris Phillips, - PowerPoint PPT PresentationTRANSCRIPT
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Results of automatic, high time resolution GRB follow-up with the Parkes 12 m
Keith [email protected] Institute for Astronomy (SIfA) University of SydneyCSIRO Astronomy and Space ScienceCAASTRO
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
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Gamma ray bursts
Long GRB (>2s) Collapse of massive star, orShort GRB (< 2s) Binary merger ?
Gamma rays
Gamma Ray Coordinate
Network (GCN)
CoordinatesParkes 12m
Internet
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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
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Bucket Feed
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Installation
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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
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Single pulse detection
6.6 σ pulse (~7 Jy), 25 ms wide, 524s after GRB 101011A
GRB 101011A
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Single pulse detection
6.2 σ pulse (~7 Jy), 6 ms wide, 1076 s after GRB 100704A
GRB 100704A
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Correspondence with X-ray break
GRB 101011A
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Correspondence with X-ray break - 2
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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
Keith Bannister 12
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Keith Bannister 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 junksbronews.com
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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
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A shameless plug
Two new techniques for antenna-coherent detection of dispersed radio pulses:
The Chirpolator & The Chimageator
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2011 ApJS,196 16B
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Chirpolator: de-disperse thyself
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y(t)=x1(t) x2*(t)
time
frequency
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Δf = ˙ f Δty(t)
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f = ˙ f ΔtFFT(y(t))
frequency
Y(f)time
frequency
Δt€
˙ f
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Δf = ˙ f Δt
x1(t)B
T
x2(t)
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x1(t) = exp( jπ˙ f t 2)
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x2(t) = exp( jπ˙ f (t − Δt)2)
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y(t) = x1(t)x2*(t) = exp( jπ˙ f (2tΔt − (Δt)2))
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Y ( f ) = D( f − Δf )Φ(Δf )
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Keith Bannister 17
Computational Costs
Pre integrator Post integrator
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Data Rates
Keith Bannister 18