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

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’’ dispersion Faraday rotation scattering Influence of ISM  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 1. “GIANT” Intensity B1937+21 May 30, 1999 Tidbinbilla (Aus) @1650 MHz B = 2×16 MHz S peak = 65000 Jy

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

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

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

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

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

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

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

12. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Measurements of pulse broadening and decorrelation bandwidth f (MHz)S peak (Jy)Duration (μs)Energy (Jy·μs)Telescope CRAB Pulsar 231504·10 6 6·10 8 UTR-2 (Kharkov) 1117001.5·10 4 10 7 BSA (Puschino) 4304·10 5 1506·10 7 NCRT (Medicina) 6005·10 4 502.5·10 5 64-m (Kalyazin) 120010 5 88·10 5 93-m WSRT 22005·10 6 0.15·10 5 64-m (Kalyazin) 850010000.0022Arecibo Millisecond Pulsar B1937+21 43040251000Arecibo 430200255000Arecibo 142060001 Arecibo 16506.5·10 4 0.07400070-m (Tidbinbilla) 210063000.08500100-m GBT 23802000.480Arecibo

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

14. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Average ACF/CCF of GRPs Instant Spectra B1937+21 N GP = 22 S peak > 1.2 kJy ν d ≈ 4 MHz

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

16. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ B1937+21 2D CCF between dynamic spectra in LCP and RCP frequency: Δν d =3.79±0.04 MHz large scale Δν d =16.5±0.8 MHz time: t s =10.4±0.1 min large scale t s =46.2±0.4 min

17. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ τ s = 40±4 ns C = 2πτ s Δν d = 0.95±0.1 Τ broad ≈ 94±5 ns

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

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

20. VLBI of GRPs June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ ` 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. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI: KL–ARO The first ever !!! Algonquine 46-m Kalyazin 64-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 LCP, LSB + USB

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

23. VLBI : Software correlation June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ delay compensation τ g (t) = a + b(t-t 0 ) + c(t-t 0 ) 2 + d(t-t 0 ) 3 decoding dedispersion H(ν) = H(ν 0 +Δν) = exp DM = 56.737 pc/cm 3 τ DM = 660 μs dt = 8192 μs (N = 262144) fractional bit correction fringe compensation exp (–j2πν 0 τ g (t)) correlation via FFT dT = 32 μs (m = 1024) σ CCF = 1/√m σ CCF = 0.031 6σ = 0.186 detection rate is about 5GPs per minute postcorrelation to determine delay and phase residuals – i2πDΔν 2 ν 0 2 (ν o +Δν) ()

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

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

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

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

28. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI : Residual phase / delay Quasar DA193 Δ t = 1 s (SNR=30 ) rms = 2 ns –3 ÷ 6 ns

29. D(τ) = June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI : Structure functions Crab DA193 3 10-min sets

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

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

32. June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI : Individual CCF ARO-KL KL LCP-RCP Shifted to coincide with ARO-KL 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 GRPs from the CRAB Puzzling absence of correlation between LCP and RCP diffraction spectra

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

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

37. May 15, 2006363 rd Heraeus Seminar GPs Polarization

38. May 15, 2006363 rd Heraeus Seminar LCPRCP GPs Polarization

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