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

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

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”)

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Properties of GRPs 1. “GIANT” Intensity B May 30, 1999 Tidbinbilla MHz B = 2×16 MHz S peak = Jy

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

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

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 2. Short Duration May 30, 1999 Tidbinbilla MHz B = 2×16 MHz B Giant pulses of B are extremely short, generally < 15 ns

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ 2. Short Duration Jun 6, m MHz B tot = 64 MHz B GP intrinsic width < 8ns

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

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, MHz B = 26 MHz B

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

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 ·10 6 6·10 8 UTR-2 (Kharkov) · BSA (Puschino) 4304· ·10 7 NCRT (Medicina) 6005· · m (Kalyazin) · m WSRT 22005· · m (Kalyazin) Arecibo Millisecond Pulsar B Arecibo Arecibo Arecibo · m (Tidbinbilla) m GBT Arecibo

LCPRCP June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ GRPs Instant Spectra B

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

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Dynamic spectrum of regular emission B RCP LCP

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ B D 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

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

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ CRAB Pulsar Popov et al., Astron.Rep. 2006, 50, 562 (astro-ph/ ) MHz

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ –4.2±0.3 B CRAB –3.5±0.1 τ–ν Dependence

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

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

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

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 = pc/cm 3 τ DM = 660 μs dt = 8192 μs (N = ) 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 = σ = detection rate is about 5GPs per minute postcorrelation to determine delay and phase residuals – i2πDΔν 2 ν 0 2 (ν o +Δν) ()

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

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

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

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!!

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

D(τ) = June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ VLBI : Structure functions Crab DA min sets

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

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

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

June 22, 2006 “Scattering and Scintillation in Radio Astronomy’’ Summary Measurements of scintillation parameters for the CRAB Pulsar and B First VLBI observations of GRPs from the CRAB Puzzling absence of correlation between LCP and RCP diffraction spectra

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

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

May 15, rd Heraeus Seminar GPs Polarization

May 15, rd Heraeus Seminar LCPRCP GPs Polarization

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