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A Tale of Two Telescopes - Scintillation studies using LEAP and - - PowerPoint PPT Presentation
A Tale of Two Telescopes - Scintillation studies using LEAP and - - PowerPoint PPT Presentation
A Tale of Two Telescopes - Scintillation studies using LEAP and LOFAR Robert Main Olaf Wucknitz, Tim Sprenger, Geetam Mall Members of the LEAP Team 1 LEAP 2 LEAP 3 LEAP Large European Array for Pulsars 4 LEAP Large European Array for
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LEAP
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LEAP
Large European Array for Pulsars
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LEAP
Large European Array for Pulsars
- Monthly simultaneous observations
- Coherently add all telescopes
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Effective 194m dish “6th telescope” of EPTA
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LEAP
Large European Array for Pulsars Ideal for Scintillation
- Large collecting area
- Baseband data is kept from the
coherent addition
- LEAP is an interferometer!
- Monthly simultaneous observations
- Coherently add all telescopes
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Effective 194m dish “6th telescope” of EPTA
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7 J1713+0747
175 MHz 16 MHz 1 MHz
Scintillation on a variety of Scales
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B1937+21 J0751+1807 J1713+0747
A zoo of parabolic arcs in MSPs!
M28A
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B1937+21 J0751+1807 J1713+0747
A zoo of parabolic arcs in MSPs!
M28A
B1933+16, Our Pol. Cal
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B1937+21 J0751+1807 J1713+0747
A zoo of parabolic arcs in MSPs!
M28A
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B1933+16, Our Pol. Cal
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Measuring Timing Delays – Application to J0613-0200
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Sum over Gives
Measuring Timing Delays – Application to J0613-0200
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Measuring Timing Delays – Application to J0613-0200
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Scattering Variations over 5 years
- Currently uncorrected for in timing
Similar method as Hemberger & Stinebring 2008
Arc curvature and scattering variations – Application to J0613-0200
Annual variation of scintillation:
- Measure distance / orientation
- Needs a joint fit with orbital parameters
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LEAP Summary
- Promising early results!
– Limited by I/O
(~200 TB of data re-reduced so far)
- Immediate uses for these data:
– Monitor scattering delays – Distances to scattering screens – Orbital parameters
- In Progress
– Use time delays / visibilities
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LEAP
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LEAP
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- Wide-band: 110 – 190 MHz
- LOFAR core has highest sensitivity
- Each station can separately
record baseband
- 6 German stations, can be used in
standalone mode for bright pulsars
Low-Frequency Array
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- Wide-band: 110 – 190 MHz
- LOFAR core has highest sensitivity
- Each station can separately
record baseband
- 6 German stations, can be used in
standalone mode for bright pulsars
Low-Frequency Array
2 Ongoing Projects
B1133+16 - “Interstellar Interferometry” B0655+64 – Orbits with scintillation
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B1133+16,single GLOW station (DE 601)
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Map Scattering Screen using Multiple Stations
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Screen aligned with baseline Maximum time delay
In 1D screen, patterns differ only by a time delay
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Screen 45 degrees off baseline Smaller time delay
In 1D screen, patterns differ only by a time delay
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Screen perpendicular to baseline Zero time delay
In 1D screen, patterns differ only by a time delay
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B1133+16 with 3 Stations
- 50 0 50
- 50 0 50
Amplitude Phase
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Map of Scattering Screen
Distance to Pulsar = 370 pc Distance to Screen = 230+-10 pc Screen extent = 36 mas = 8.5 AU
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Map of Scattering Screen
Distance to Pulsar = 370 pc Distance to Screen = 230+-10 pc Use as “Interstellar Interferometer”! Resolution of ~20000km at pulsar Screen extent = 36 mas = 8.5 AU
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Constrains Emission Regions to km!
“Interstellar Interferometer”! Resolution of ~20000 km at pulsar Measure time delay of scintillation across the pulse profile
Pulse Phase I n t e n s i t y ( a r b ) Separation (km) Pulse Phase I n t e n s i t y ( a r b )
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Constrains Emission Regions to km!
“Interstellar Interferometer”! Resolution of ~20000 km at pulsar Measure time delay of scintillation across the pulse profile Submitted proposal: 2-hours LOFAR core + GLOW & international stations ~ 10 km astrometric precision!
Pulse Phase I n t e n s i t y ( a r b ) Separation (km) Pulse Phase I n t e n s i t y ( a r b )
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Scintillation rate proportional to velocity parallel to scattering screen
Solving Orbits through Scintillation
26 hours DE 601 – PSR B0655+64 Secondary Spectrum varies throughout Orbit
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Scintillation rate proportional to velocity parallel to scattering screen
Solving Orbits through Scintillation
26 hours
No symmetry axis
- 2D screen?
- Motion of subimages?
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Scintillation rate proportional to velocity parallel to scattering screen
Solving Orbits through Scintillation
26 hours
No symmetry axis
- 2D screen?
- Motion of subimages?
Simulation
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Scintillation rate proportional to velocity parallel to scattering screen
Solving Orbits through Scintillation
No symmetry axis
- 2D screen?
- Motion of subimages?
Velocity over orbit (from arc curvature)
Measuring something very precisely, but we need to understand our screen
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LOFAR Core Reveals an Arc
- Combining core with GLOW and international stations
- Observing Campaign in Progress! (LC12_007)
Time (2 hours) Frequency (130-140 MHz)
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In Progress!
- 6 ft (mHz) 6
- 90 tau (mus) 90
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In Progress!
- 90 tau (mus) 90
- 6 ft (mHz) 6
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In Progress!
- 90 tau (mus) 90
- 6 ft (mHz) 6
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In Progress!
- 90 tau (mus) 90
- 6 ft (mHz) 6
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In Progress!
- 90 tau (mus) 90
- 6 ft (mHz) 6
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In Progress!
- 90 tau (mus) 90
- 6 ft (mHz) 6
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In Progress!
- 90 tau (mus) 90
- 6 ft (mHz) 6
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In Progress!
- 90 tau (mus) 90
- 6 ft (mHz) 6
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In Progress!
No distance / orientation of the screen yet More data to be taken, data needs to be looked at in more detail
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- LEAP and LOFAR are ideal telescopes for scintillation
- Promising early results
– Scattering variations – Solving for Scattering Screens – Orbital Parameters – Probing emission regions
- (In progress) LEAP and LOFAR as an interferometer