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Crab Giant Pulses

Crab Giant Pulses. W. Majid * , S. Ellingson (PI), C. Garcia- Miro , T. Kuiper, J. Lazio , S . Lowe, C. Naudet , D. Thompson, K. Wagstaff. * Jet Propulsion Laboratory, California Institute of Technology.

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Crab Giant Pulses

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  1. Crab Giant Pulses W. Majid*, S. Ellingson (PI), C. Garcia-Miro, T. Kuiper, J. Lazio, S. Lowe, C. Naudet, D. Thompson, K. Wagstaff *Jet Propulsion Laboratory, California Institute of Technology W. Majid

  2. Intense narrow pulses with a pulse energy many times that of mean pulse energy: Speak>~ 100 x <S> Characterized by a power-law distribution of pulse energies Extremely rare phenomenon To date only ~10 pulsars have been known to exhibit this behavior out of ~2000 known pulsars Bursts fall into narrow phase window in pulse profile The Crab exhibits ns bursts - limited by hardware (Hankins et al. 2007) Suggests region of emission is size of a basketball Smallest entity ever detected outside Solar system Extreme brightness temperature - brightest in galaxy Coincident with high frequency emission Some Facts about Giant Pulses W. Majid

  3. Only way to detect extragalactic pulsars Important for understanding the magnetospheres of pulsars Emission mechanism is not well understood How high energy emission might be linked with radio emission Conflicting claims on few detections Are GPs restricted to small group of pulsars or many waiting to be discovered Galactic pulsar population may be larger than we thought Wide range of single pulse properties apparent Algorithms relevant to transient detection phenomenon Why GPs? W. Majid

  4. Why at Low Frequencies Examine how the properties of pulse emission evolves Pulse energy frequency dependence Scattering and dispersive effects more prominent Low Frequency Studies • Previous Studies • Early studies at 200 MHz suggested a turnover of the spectrum (Manchester & Taylor 1977) • 23, 111, and 600 MHz studies by Popov et al. 2006 suggests very steep falloff at low frequencies • MWA detected a handful of GPs at 200 MHz, none at 100 MHz (Bhat et al. 2007) • LOFAR LBA studies 32-80 MHz (Stappers et al. 2011) W. Majid

  5. Why at Low Frequencies Examine how the properties of pulse emission evolves Pulse energy frequency dependence Scattering and dispersive effects more prominent Low Frequency Studies • Previous Studies • Early studies at 200 MHz suggested a turnover of the spectrum (Manchester & Taylor 1977) • 23, 111, and 600 MHz studies by Popov et al. 2006 suggests very steep falloff at low frequencies • MWA detected a handful of GPs at 200 MHz, none at 100 MHz (Bhat et al. 2007) • LOFAR LBA studies 32-80 MHz (Stappers et al. 2011) W. Majid

  6. Low Frequency Studies • LWA Advantages • 30% greater sensitivity (256 stands, coherently combined) • Up to ~80 MHz BW (with 3 beams) • Location better for Crab • Multi-beaming capability • Low RFI environment • Excellent prospects for pulsar and transient science W. Majid

  7. Crab Giant Pulse Campaign 160 hours over 10 months Can coordinate with higher frequencies at GAVRT, GBT Can coordinate with Fermi for radio/gamma correlation studies Single Dispersed Pulse Survey 160 hours over 11 months Survey will establish limits on LIGO sources, discover or study RRATs GCN-triggered observations of GRBs 80 hours over 10 months Dispersive delay gives time for interrupting observing and repointing New MCS event-triggered observing capability applicable to other projects Single Dispersed Pulses with the LWA (P. Ray) W. Majid

  8. Crab Pulsar Observations S. Ellingson W. Majid

  9. Crab pulsar was observed at L-band from 19:57:00 – 21:40:00 2012-04-29 Observation of the Crab W. Majid

  10. Crab pulsar was observed at L-band from 19:57:00 – 21:40:00 2012-04-29 Observation of the Crab W. Majid

  11. 2012-04-29 Observation of the Crab 13 kJy, 8 ms wide W. Majid

  12. LWA Observation: 4 Beams: 2 pointed at the Crab; 2 pointed off the Crab 0.7 hr in RA Beams 1&3: 60, 76 MHz (dual pol) Beams 2&4: 28, 44 MHz BW = 19.6 MHz 4x1TB drives (mattingly,koubek,kalbfus, and roosa - MLB?) 2012-04-29 Observation of the Crab W. Majid

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  16. 2012-04-29 Observation of the Crab • Using LSL tools: looking at spectra, waterfall plots, time series • Extracting voltage data to apply coherent dedispersion on 50s of data starting at the time of the L-band GP • Stay tuned … W. Majid

  17. Implications for Single Dispersed Pulse Detections • Pulsars Sources (Known) • Giant Pulses • Rotating Radio Transients (RRATs) • Anomalously Intensive Pulses (AIPs) • Suspected Sources • Prompt Emission from GRBs • Compact Object Mergers (LIGO/VIRGO events) • Evaporating Primordial Black Holes • Cosmic Strings • Unknowns • Magnetars? • Much unexplored search space Period derivative (s s-1) (Keane et al. 2011) Period (s) W. Majid

  18. FIN W. Majid

  19. Crab GPs Microstructure W. Majid

  20. Source of GP emission currently unknown Changes in coherence of radio emission Changes in pair creation rate in the pulsar magnetosphere Changes in beaming direction Correlation studies with high energy emission is one way to pin-point the origin of GP emission Look for increase in high-energy flux during GP emission Look for frequency dependence of GP emission and coincidence with high energy emission Fermi Studies W. Majid

  21. Expect ~100 coincidences over the course of this study Fermi Studies (in progress) W. Majid

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