GALACTIC ASTRONOMY II: PULSARS

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GALACTIC ASTRONOMY (II) PULSARS

• _____________________________
• Jon Marcaide

ASI, Castel San Pietro Terme, 18 September 2001
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GALACTIC ASTRONOMY (II) PULSARS
JON MARCAIDE ASI, 18 Sept 2001 Castel San Pietro
Terme
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Pulsar VLBI observations are (gated) phase-delay
observations (phase referenced observations)
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Campbells enumeration of possible uses of
pulsars

• (1) DISTANCES, along with independent dispersion
  measures, can yield the electron density
  integrated along the light of sight and thus
  check on models of Galactic electron density
  distribution obtained with pulsar timing
  techniques

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Campbells enumeration of possible uses of
pulsars

• (2) DISTANCES, along with independent measures of
  the angular diameter of pulsars scattering disks
  at two or more frequencies, can determine
  similarly integrated values for the coefficient
  and exponent of the power-law spectrum of the
  electron density spatial fluctuations, which may
  provide insights into the mechanisms driving
  turbulence in the ISM.

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Campbells enumeration of possible uses of
pulsars

• (3) DISTANCES and PROPER MOTIONS, along with
  independent age estimates, can provide bounds on
  the birth places of pulsars

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Campbells enumeration of possible uses of
pulsars

• (4) POSITIONS, along with independent pulse
  time-of-arrival data, can contribute toward a tie
  between the extragalactic (Earth-rotation-based)
  and dynamic (Earth-orbit-based ) reference
  frames.

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Where are we in Campbells enumeration?

• (1) Compatibility on electron density estimates
  starting to appear around 2000
• (2) I do not know
• (3) Attempts being made
• (4) Frames tied to 0.3 mas level

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Tests

• Chatterjee99 VLBA Scientific Memo 18
• How accurate is phase referencing at L-band?
• In-beam (12) nodding calibrator (4 deg)
• SUCCESS WILL DEPEND ON THE DAY

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Day 1
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Day 2
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How about a black hole!!!!! proper motion??????

• Mirabel et al. Nature, 13 September 2001!!!

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