A bright millisecond

radio burst of Extragalactic

originDuncan Lorimer, Matthew Bailes, Maura McLaughlin, David Narkevic and Froney

CrawfordScience (in press) astro-ph/0709.4301

Talk Outline

• Dispersion by the interstellar medium

• Pulsar Surveys• RRATs• Giant Pulses• LMC/SMC Pulsar Survey• An enormous pulse• Location• Potential • Future directions

Pulse Dispersion

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DM = ne0

D

∫ dl

Standard pulsar search

Single pulse search

The RRATs

• McLaughlin et al. (2006)– Discovered repeating impulsive bursts at the same DM

– Gap ~4->120 minutes

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

Giant Pulses

• Unresolved on us timescales• From young or millisecond pulsars

• Power-law distribution of energies

Pulsar Surveys with Parkes

MB Survey

Swinburne Surveys

Swinburne Surveys

BurgaySurvey

BurgaySurvey

SMC/LMC surveys

LMC/SMC bursts?

• Searched DM 0-5000 cm-3 pc.• Found 3 giants from one pulsar– Seen already by Johnston & Romani

• Der Wunderpuls…• DM=375 cm-3pc!

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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W = 5msυ

1400 MHz

⎛

⎝ ⎜

⎞

⎠ ⎟−4.8

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

• Doesn’t repeat in 20 days of observing

Where?

X x

x

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)!!

If it is a PSR or RRAT

• Should repeat• Original pulse 100x detection threshold!

• 40 hours of follow-up @ 20cm• Nothing!

What then?

• Points to a one-off event?• Distance?

– If DM (MWG+SMC ~ 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 ns+ns coalescence– Also Hyperflares on Magnetars?– 100s per day and still invisible

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

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)

A dedicated search• Green Bank Extragalactic Radio Transient Experiment (GERTIE)– 3x 85’ telescopes (3 square degree coverage)