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Pulsars ASTR2110 Sarazin

Pulsars ASTR2110 Sarazin. Crab Nebula. July 4, 1054, Chinese “guest star”. What is energy source?. Pulsars. Cambridge radio array, excellent time resolution, broad sky coverage November 28, 1967: Jocelyn Bell (-Burnell) PSR 1919+21. Pulsars. Pulsars.

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Pulsars ASTR2110 Sarazin

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  1. PulsarsASTR2110Sarazin

  2. Crab Nebula July 4, 1054, Chinese “guest star” What is energy source?

  3. Pulsars Cambridge radio array, excellent time resolution, broad sky coverage November 28, 1967: Jocelyn Bell (-Burnell) PSR 1919+21

  4. Pulsars

  5. Pulsars Terrestrial, etc.? No, no parallax Little Green Men? No. pulses individually irregular no modulation broad-band no planetary motion

  6. Pulsars Terrestrial, etc.? No. no parallax Little Green Men? No. pulses individually irregular no modulation broad-band no planetary motion

  7. Pulsars Terrestrial, etc.? No. no parallax Little Green Men? No. pulses individually irregular no modulation broad-band no planetary motion

  8. Pulse Profile: Radio

  9. Pulse Profiles

  10. Pulsars: Properties mid 1968 Periods: P = 0.2 – 2 seconds | d P / dt | < 10-13 sec/sec, very good clock dP/dt > 0, pulses slowing very slightly Pulse duration >~ 20 ms

  11. Size limit D D ≤ c dt ≲ 103 km M ≳ M → WD, NS, or BH

  12. Origin of Clock?  • Orbital Period? • a ~ 108 cm • as loses energy, binary gets smaller, period gets shorter  • Pulsation Period? • P ∝ 1/2, → ~ 109 gm/cm3, between WD and NS? • Why would pulsation period change with time?  • Rotation Period? • vrot < vesc→ cannot be WD • Prot (NS) > 1 msec = 0.001 sec → OK • Rotating BHs are symmetric → no reason for pulses • As rotating object loses energy, slows down, Prot increases

  13. Pulsars = Rotating Neutron Stars

  14. Crab Pulsar

  15. Crab Pulsar 1968 P = 0.033 sec dP/dt = 4 x 10-13 tslow ~ P/(dP/dt) ~ 2000 years ~ time since supernova Decrease in rotational kinetic energy = energy from Crab Nebula

  16. Pulsar Model

  17. Pulsar Model

  18. Fermi Gamma-Only Pulsars

  19. How Does Pulsar Power Crab Nebula?Pulsar Wind Nebulae red = optical blue = X-ray

  20. Pulsar Wind Nebulae Crab Chandra Xray

  21. Pulsar Wind Nebulae

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