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Does the fine structure constant vary?: A detailed investigation into systematic errors

Does the fine structure constant vary?: A detailed investigation into systematic errors. With: Chris Churchill (PSU) Victor Flambaum (UNSW) Jason Prochaska (UCSC) Wallace Sargent (Caltech) Rob Simcoe (Caltech) John Webb (UNSW) Arthur Wolfe (UCSD).

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Does the fine structure constant vary?: A detailed investigation into systematic errors

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  1. Does the fine structure constant vary?:A detailed investigation into systematic errors With: Chris Churchill (PSU) Victor Flambaum (UNSW) Jason Prochaska (UCSC) Wallace Sargent (Caltech) Rob Simcoe (Caltech) John Webb (UNSW) Arthur Wolfe (UCSD)

  2. Outline:Systematic errors for the MM method • Detailed analyses: • Atmospheric dispersion effects • Isotopic ratio evolution • Consistency checks • Line removal • Other tests for simple, unknown systematics

  3. Candidate systematic errors: • Wavelength calibration errors – JOHN’S TALK • Instrumental profile variations • Laboratory wavelength errors (wz=w0+qx) • Line blending • Temperature changes during observations • Heliocentric velocity variation • Atmospheric dispersion effects • Isotopic ratio evolution • Differential isotopic saturation • Hyperfine structure effects See Murphy et al., 2001, MNRAS, 327, 1223 for details •  •  •  •  •  •  • ? • ? •  • 

  4. Atmospheric dispersion effects:

  5. Atmospheric dispersion results: Pre-rotator Post-rotator Rotator

  6. Isotopic ratio evolution:

  7. Isotopic ratio evolution:

  8. Isotopic ratio evolution results: Isotope

  9. Line removal checks:

  10. Removing MgII2796: Post-removal Pre-removal Line Removal

  11. Removing MgII2796: Post-removal Pre-removal Line Removal

  12. Number of systems where transition(s) can be removed Pre-removal Post-removal Transition(s) removed

  13. Other line-removal tests: Low-z (0.5 – 1.8) High-z (1.8 – 3.5) ZnII FeII SiIV FeII Positive MgI, MgII Mediocre Anchor Mediocre Negative CrII

  14. Correcting for both systematics: Rotator + Isotope

  15. Conclusions: • Main systematics: • Atmospheric dispersion • Isotopic ratio evolution • Known systematic errors cannot explain results • Nor can simple, unknown systematics Future: • Iodine cell measurements planned for Keck • Independent optical check required: VLT & Subaru • Sleep loss?

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