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Probing cosmic plasma with Giant Radio Pulses

Astro Space Center. York University, Toronto, Canada. June 22, 2006. “Scattering and Scintillation in Radio Astronomy’’. Probing cosmic plasma with Giant Radio Pulses. Vladislav Kondratiev, Michael Popov, Vladimir Soglasnov. Norbert Bartel, Wayne Cannon, Alexander Novikov. June 22, 2006.

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Probing cosmic plasma with Giant Radio Pulses

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  1. Astro Space Center York University, Toronto, Canada June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Probing cosmic plasma with Giant Radio Pulses Vladislav Kondratiev, Michael Popov, Vladimir Soglasnov Norbert Bartel, Wayne Cannon, Alexander Novikov

  2. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Outline • ISM: observing effects • Properties of giant radio pulses (GRP) • Measurements of pulse broadening and decorrelation bandwidth • VLBI of GRPs

  3. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Influence of ISM • dispersion • Faraday rotation • scattering • diffraction in radio spectra • pulse broadening • scintillations • image angular smearing • multiple imaging events (“superresolution”)

  4. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Properties of GRPs B1937+21 1. “GIANT” Intensity Speak = 65000 Jy May 30, 1999 Tidbinbilla (Aus) @1650 MHz B = 2×16 MHz

  5. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 1. “GIANT” Intensity CRAB Pulsar Speak≈ 5 mln. Jy • March 2005 • Kalyazin (Rus) • @2244MHz • B = 16 MHz • ∆t = 31.25 ns

  6. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 1. “GIANT” Intensity CRABat Kalyazin@2244 MHz ∆t = 31.25 ns

  7. Giant pulses of B1937+21 are extremely short, generally < 15 ns June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 2. Short Duration B1937+21 May 30, 1999 Tidbinbilla (Aus) @1650 MHz B = 2×16 MHz

  8. GP intrinsic width < 8ns June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 2. Short Duration B1937+21 Jun 6, 2005 100-m GBT @2100 MHz Btot = 64 MHz

  9. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 2. Short Duration CRAB Arecibo @5.5 GHz B = 500 MHz ∆t = 2 ns Hankins et al., 2003, Nature, 422, 141

  10. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 3. High Degree of Polarization B1937+21 GBT 100-m March 26, 2004 @1400 MHz B = 26 MHz Pulsar was observed as a calibrator for the project GBT03A-002 (Kardashev et al.)

  11. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 3. High Degree of Polarization CRAB Nov 24-26, 2003 64-mKalyazin @594MHz B = 8MHz

  12. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Measurements of pulse broadening and decorrelation bandwidth

  13. LCP RCP June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ B1937+21 GRPs Instant Spectra

  14. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Average ACF/CCF of GRPs Instant Spectra B1937+21 NGP = 22 Speak > 1.2 kJy νd ≈ 4MHz

  15. RCP LCP June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Dynamic spectrum of regular emission B1937+21

  16. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 2D CCF between dynamic spectra in LCP and RCP B1937+21 frequency: Δνd=3.79±0.04 MHz large scale Δνd=16.5±0.8 MHz time: ts=10.4±0.1 min large scale ts=46.2±0.4 min

  17. Τbroad ≈ 94±5 ns τs= 40±4 ns June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ C = 2πτsΔνd = 0.95±0.1

  18. Kalyazin @600 MHz UTR-2 @23 MHz BSA @111 MHz June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Popov et al., Astron.Rep. 2006, 50, 562 (astro-ph/0606025) CRAB Pulsar

  19. B1937+21 CRAB –4.2±0.3 –3.5±0.1 June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ τ–ν Dependence

  20. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI of GRPs ` WHY? Precise instant measurements of the phase of visibility (high SNR 100÷1000, no integration) -> this simplifies calibration of space-ground radio interferometer (e.g., RADIOASTRON) Measuring short-term variations of visibility function to study interstellar scintillations

  21. Kalyazin 64-m June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: KL–ARO Algonquine 46-m July 19-20, 2005 @ 2244 MHz B = 2×16 MHz S2 VLBI Recorder Sources: DA193 (4×10min) CRAB Pulsar (2×3 hours) RCP + LCP, USB The first ever !!! LCP, LSB + USB

  22. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: Examples of GRPs

  23. VLBI: Software correlation • delay compensation • τg(t) = a + b(t-t0) + c(t-t0)2 + d(t-t0)3 • decoding • dedispersion • H(ν) = H(ν0+Δν) = exp • DM = 56.737 pc/cm3τDM = 660 μs dt = 8192 μs (N = 262144) • fractional bit correction • fringe compensation • exp (–j2πν0τg(t)) • correlation via FFT • dT = 32 μs (m = 1024) σCCF = 1/√m σCCF = 0.031 • 6σ = 0.186 detection rate is about 5GPs per minute • postcorrelationto determine delay and phase residuals i2πDΔν2 ν02(νo+Δν) ( ) – June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’

  24. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: CCF Example module (SNR = 56) real part imaginary part

  25. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: Expected angular broadening Θd2 = cτ/ d, d = 2kpc,τ= 200 ns =>θd ≈ 0.2 mas Θres= λ/ s,s – baseline ARO-KL ~ 6500 km,λ= 13 cm Θres≈ 4 mas – 20 times largerθd => We can consider Crab Pulsar as a point source

  26. VLBI: Residual phase behavior June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ CRAB Pulsar July 20, 2005 glitch in fLO≈ 6.6 mHz Δν/ν = 3×10-12

  27. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: Residual phase and delay behavior regular drift in phase is not accompanied by the corresponding drift in delay!! ± 30ns

  28. VLBI: Residual phase / delay June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Quasar DA193 Δt = 1 s (SNR=30) –3 ÷ 6 ns rms = 2 ns

  29. 3 10-min sets Crab DA193 June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: Structure functions D(τ) = <[φ(t) – φ(t + τ)]2>

  30. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: Diffraction GPs spectra Kalyazin LCP

  31. ARO-KL LCP ARO-KL LCP There is no notable correlation between diffraction spectra for the LCP and RCP channels! KL LCP-RCP June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: Average CCF For all 25 strong GPs Δνd≈ 1MHz

  32. ARO-KL Shifted to coincide with ARO-KL KL LCP-RCP June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: Individual CCF The CCFs are in a good agreement when being shifted in frequency lag by the half period of the regular pattern

  33. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Summary • Measurements of scintillation parameters for the CRAB Pulsar and B1937+21 • First VLBI observations of GRPsfrom the CRAB • Puzzling absence of correlation between LCP and RCP diffraction spectra

  34. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Thank you

  35. June 17, 2004 NRAO Green Bank Colloquium Arecibo Observatory Library Colloquium Polarization ― the Crab Pulsar Kalyazin (Russia) Nov 24-26, 2003 F = 594MHz B = 8 MHz Δt = 125 ns

  36. GPs Polarization May 15, 2006 363rd Heraeus Seminar

  37. GPs Polarization May 15, 2006 363rd Heraeus Seminar LCP RCP

  38. The spectrum of the strong GP at 10:18:03 LCP RCP

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