A bright millisecond radio burst of Extragalactic origin

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A bright millisecond radio burst of Extragalactic
origin

• Duncan Lorimer, Matthew Bailes, Maura McLaughlin,
  David Narkevic and Froney Crawford
• Science (in press)
• astro-ph/0709.4301

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Talk Outline

• Dispersion by the interstellar medium
• Pulsar Surveys
• RRATs
• Giant Pulses
• LMC/SMC Pulsar Survey
• An enormous pulse
• Location
• Potential
• Future directions

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Pulse Dispersion
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Standard pulsar search
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Single pulse search
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The RRATs

• McLaughlin et al. (2006)
• Discovered repeating impulsive bursts at the same
  DM
• Gap 4-gt120 minutes

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RRAT Properties

• Power law distribution of energies
• Regular gaps between pulses
• Associated with
• Rotating
• Radio
• Transients
• Another manifestation of neutron stars
• Luminosity not enough to see beyond Milky Way
  Galaxy

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Giant Pulses

• Unresolved on us timescales
• From young or millisecond pulsars
• Power-law distribution of energies

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Pulsar Surveys with Parkes
Burgay Survey
Burgay Survey
Swinburne Surveys
MB Survey
Swinburne Surveys
SMC/LMC surveys
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LMC/SMC bursts?

• Searched DM 0-5000 cm-3 pc.
• Found 3 giants from one pulsar
• Seen already by Johnston Romani
• Der Wunderpuls
• DM375 cm-3pc!

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Giant Pulse Characteristics

• Seen in 3/13 beams
• Side-lobes suggest 20 Jy intensity
• Analog level setting suggests 40 Jy
• Adopt (30/-10) Jy.
• Width fn(frequency)

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An astrophysical origin

• Knows about Cold Plasma Dispersion law
• Knows about Kolmogorov Scattering law
• Appears only in 3 adjacent beams out of 13
• From the sky direction
• Doesnt repeat in 20 days of observing

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Where?
x
X
x
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SMC Pulsar DMs

• 70 pc/cc (far from H-alpha)
• 76 pc/cc (far from H-alpha)
• 105 pc/cc (Near H-alpha)
• 125 pc/cc (Near H-alpha)
• 201 pc/cc (Near H-alpha emission)
• 375 pc/cc (far from any H-alpha)!!

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If it is a PSR or RRAT

• Should repeat
• Original pulse 100x detection threshold!
• 40 hours of follow-up _at_ 20cm
• Nothing!

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What then?

• Points to a one-off event?
• Distance?
• If DM (MWGSMC 70 units)
• Up to 1 Gpc!
• Adopt 500 Mpc - first detection ionized IGM!
• 1040 ergs in radio required!
• Event rate (1/20 days/5 sq deg)
• Could be SNe, GRB or nsns coalescence
• Also Hyperflares on Magnetars?
• 100s per day and still invisible

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Worrying bits

• 100x detection threshold
• Might expect power law distribution
• More distant events fainter
• Different orientations fainter too?
• Proximity to SMC
• Only place people have looked!
• Re-processing in progress
• Swinburne Surveys
• SMC/LMC Surveys

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If we find more

• Great synergy with other wavebands
• Sub-arcsec position from VLBI
• Host Galaxy Redshift Determination
• Integrated baryonic content of Universe
• 100 ionised
• Many VLBI events
• Baryonic density of the Universe(Z)

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A dedicated search

• Green Bank Extragalactic Radio Transient
  Experiment (GERTIE)
• 3x 85 telescopes (3 square degree coverage)