Fast Radio Bursts Laura Spitler Max-Planck-Institut für Radioastronomie 11. April 2015
Lorimer Burst Bright burst discovered in the reprocessing of archival data from a pulsar survey A Bright Millisecond Radio Burst of Extragalactic Origin Lorimer et al., Science, 2007 10 published FRBs
Duration of pulse: 1-10 ms Appear to be nonrepeating Flux densities: 0.3-3 Jy The observed frequencydependent delay exactly follows expect dispersion through a cold plasma. Thornton et al 2013 Found by surveys for radio pulsars Spitler et al 2014
Parkes Radio Telescope Arecibo Radio Telescope Image credit: NAIC - Arecibo Observatory, a facility of NSF Image credit: Stephen West New South Wales, Australia Puerto Rico, USA Multibeam Receiver (13 beams) Discovered 9 FRBs (including the first) First measurement of polarization First detection in realtime Arecibo L-band Feed Array (7 beams) Second telescope to discover an FRB First (believable) FRB in the Galactic plane 5 unpublished FRBs coming in Chamption et al in prep
Parkes Multibeam Receiver Arecibo L-band Feed Array 13 pixel ATNF 7 pixel Spitler et al 2014 Sky frequency: 1.18-1.58 GHz Half Power Beam Width: 14 arcmin Sky frequency: 1.25-1.55 GHz Half Power Beam Width: 3.5 arcmin
Sky distribution Parkes Arecibo
Dispersion Ionized interstellar medium has a frequency-dependent index of refraction Frequency-dependent time-ofarrival to the Earth t 1 t 2 1 ν 2 1 1 ν 2 2 Frequency (MHz) Time (sec) R. Karuppusamy
Dispersion Magnitude of delay described by dispersion measure (DM) DM = D 0 n e dl t 1 t 2 =4.16 10 6 DM 1 ν 2 1,GHz 1 ν 2 2,GHz ms If you have an estimate for the number density of electrons along the line-of-sight, you can estimate the distance.
NE2001 model (Cordes and Lazio 2002) NASA/JPL-Caltech/ESO/R. Hurt WISE - NASA
NE2001 model Predict the maximum DM contribution from our Galaxy DMA DMB DMA DMB WISE - NASA Cordes and Lazio 2002
The DMs of FRBs are too large for the sources to be in our Galaxy DM = DMMilkyWay + DMIntergalacticMedium + DMHostGalaxy
Distance Estimates t obs = t MW + t IGM + t HG t MW NE2001 t HG = 100 ms/(1 + z) 2 (assuming host galaxy DM =100 pc cm -3 ) t IGM = 1200z ms (Ioka 2003 & Inoue 2004) FRB 121102: Spitler et al 2014 z =0.26 D 1Gpc FRB 110703: z =0.96 D 3.2 Gpc Thornton et al 2013
FRB Rate Calculations Canonical rate based on a detection of four FRBs: R P =1.0 +0.6 0.5 104 sky 1 day 1 Thornton et al 2013 (for Speak > 3 Jy and 1 ms) FRB 121102 discovered by the Arecibo Observatory is also consistent with this rate for comparable sensitivities Spitler et al 2014 The updated rate based on five additional FRBs from Parkes is within the uncertainties of the canonical rate Champion et al in prep
What do we know? Emission process must be coherent Tb 10 30-10 38 K Energy output is... L 10 38-10 40 ergs Spectral index is not as negative as radio pulsars
GRBs The rates are inconsistent GRBs 1 day -1 FRBs 10 4 day -1 No coincidence of FRBs with time/location of observed GRBs NASA/Swift/Mary Pat Hrybyk-Keith and John Jones
(Very) giant pulses Cordes & Wasserman 2014 Parametrize flux densities of giant pulses based off of the Crab In 10 3 years Smax = 10 8 to 10 10 Jy D = 15 to 300 Mpc Note that NNS born within a Hubble volume is ~10 4 day -1 Cordes et al 2004
Flares from SGR (magnetars) Strong x-ray flares Highly accelerated particles collide with winds and synchrotron maser emission produced at shock front (Lyubarsky 2014) The rates/energetics could be compatible with observations (Kulkarni et al 2014)
How to move forward? Improve spatial localization Counterpart at optical/x-ray/gamma-ray wavelengths Identify a host galaxy more accurate distance Increase the sample size Learn about the physics from pulse profile variations
How to move forward? Improve spatial localization Counterpart at optical/x-ray/gamma-ray wavelengths Identify a host galaxy more accurate distance Increase the sample size Realtime Detection Learn about the physics from pulse profile variations
Realtime detections and identifications Graphics Processing Unit heimdall GPU transient detection code -Written by Ben Barsdell -Factor of 10-100x faster than CPU codes Nvidia FRB needle in an RFI haystack
First two realtime FRBs from Parkes Ravi & Shannon 2015 Petroff et al 2015 Extensive follow-up with radio, optical, x- ray, and gamma-ray telescopes
Effelsberg realtime FRB survey MPIfR Effelsberg 100-m radio telescope near Bonn, Germany Detections of single pulses from the bright pulsar B0355+54
Hans Hordijk Lower frequency measurements (LOFAR) Optical counterparts X-ray/Gamma ray emission (Swift) MPIfR -More clues to astrophysical source -Host galaxy identification
Increasing the Sample Size Use variations in pulse profile to study emission mechanism and intergalactic medium Scattering Thornton et al 2013 Ravi & Shannon 2013
SKA era: cosmological probes Missing Baryon problem SKA white paper Cosmic rulers Probe intergalactic medium SKA Organization
Conclusions FRBs are short-duration radio bursts whose large dispersion measures suggest that they are of extragalactic origin. Roughly 10 4 FRBs occur each day across the entire sky The astrophysical origin of these bursts is unknown Huge amount of work to expand our knowledge through realtime surveys and expanding the fields-of-view.
Perytons: Caused by microwave ovens on Parkes site Petroff et al 2015: astro-ph/1504.01265 Can be generated when the microwave door is opened while microwave is still running.