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 Pulsars Monthly simultaneous observations ● Coherently add all telescopes ● Effective 194m dish – “6 th telescope” of EPTA 5

LEAP Large European Array for Pulsars Monthly simultaneous observations ● Coherently add all telescopes ● Effective 194m dish – “6 th telescope” of EPTA Ideal for Scintillation Large collecting area ● Baseband data is kept from the ● coherent addition LEAP is an interferometer! ● 6

Scintillation on a variety of Scales J1713+0747 175 MHz 16 MHz 1 MHz 7

A zoo of parabolic arcs in MSPs! B1937+21 J0751+1807 J1713+0747 M28A 8

A zoo of parabolic arcs in MSPs! B1937+21 J0751+1807 J1713+0747 M28A B1933+16, Our Pol. Cal 9

A zoo of parabolic arcs in MSPs! B1937+21 J0751+1807 J1713+0747 M28A B1933+16, Our Pol. Cal ? 10

Measuring Timing Delays – Application to J0613-0200 11

Measuring Timing Delays – Application to J0613-0200 Sum over Gives 12

Measuring Timing Delays – Application to J0613-0200 13

Arc curvature and scattering variations – Application to J0613-0200 Scattering Variations over 5 years - Currently uncorrected for in timing Similar method as Hemberger & Stinebring 2008 Annual variation of scintillation: - Measure distance / orientation - Needs a joint fit with orbital parameters 14

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 15

LEAP 16

LEAP 17

Low-Frequency Array 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 18

Low-Frequency Array 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 2 Ongoing Projects B1133+16 - “Interstellar Interferometry” B0655+64 – Orbits with scintillation 19

B1133+16,single GLOW station (DE 601) 20

Map Scattering Screen using Multiple Stations 21

In 1D screen, patterns differ only by a time delay Screen aligned with baseline Maximum time delay 22

In 1D screen, patterns differ only by a time delay Screen 45 degrees off baseline Smaller time delay 23

In 1D screen, patterns differ only by a time delay Screen perpendicular to baseline Zero time delay 24

B1133+16 with Amplitude Phase 3 Stations 25 -50 0 50 -50 0 50

Map of Scattering Screen Distance to Pulsar = 370 pc Distance to Screen = 230+-10 pc Screen extent = 36 mas = 8.5 AU 26

Map of Scattering Screen Distance to Pulsar = 370 pc Distance to Screen = 230+-10 pc Screen extent = 36 mas = 8.5 AU Use as “Interstellar Interferometer”! Resolution of ~20000km at pulsar 27

Constrains Emission Regions to km! ) b r a ( y t i s n e t n I Pulse Phase “Interstellar Interferometer”! ) b r Resolution of ~20000 km at pulsar a ( y t i s Measure time delay of scintillation n e t across the pulse profile n I Separation (km) 28 Pulse Phase

Constrains Emission Regions to km! ) b r a ( y t i s n e t n I Pulse Phase “Interstellar Interferometer”! ) b r Resolution of ~20000 km at pulsar a ( y t i s Measure time delay of scintillation n e t across the pulse profile n I Submitted proposal: Separation (km) 2-hours LOFAR core + GLOW & international stations ~ 10 km astrometric precision! 29 Pulse Phase

Solving Orbits through Scintillation DE 601 – PSR B0655+64 Scintillation rate proportional to velocity parallel to scattering screen Secondary Spectrum varies throughout Orbit 30 26 hours

Solving Orbits through Scintillation Scintillation rate proportional to velocity parallel to scattering screen No symmetry axis - 2D screen? - Motion of subimages? 26 hours 31

Solving Orbits through Scintillation Scintillation rate proportional to velocity parallel to scattering screen No symmetry axis - 2D screen? - Motion of subimages? Simulation 26 hours 32

Solving Orbits through Scintillation Scintillation rate proportional to velocity parallel to scattering screen 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 33

LOFAR Core Reveals an Arc - Combining core with GLOW and international stations Frequency (130-140 MHz) - Observing Campaign in Progress! (LC12_007) 34 Time (2 hours)

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! -90 tau (mus) 90 -6 ft (mHz) 6

In Progress! No distance / orientation of the screen yet More data to be taken, data needs to be looked at in more detail

Summary ● 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 44