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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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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
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Candidate systematic errors: ? Wavelength calibration errors – JOHN’S TALK ? Instrumental profile variations ? Laboratory wavelength errors ( z = 0 +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 ? ??
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Atmospheric dispersion effects:
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Atmospheric dispersion results: Pre-rotator Post-rotator Rotator
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Isotopic ratio evolution:
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Isotopic ratio evolution results: Isotope
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Line removal checks:
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Removing MgII2796: Post-removal Pre-removal Line Removal
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Removing MgII2796: Post-removal Pre-removal Line Removal
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Number of systems where transition(s) can be removed Transition(s) removed Pre-removal Post-removal
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Other line-removal tests: High-z (1.8 – 3.5) Low-z (0.5 – 1.8) FeII MgI, MgII ZnII CrII FeII Positive Mediocre Anchor Mediocre Negative SiIV
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Correcting for both systematics: Rotator + Isotope
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Conclusions: Main systematics: Atmospheric dispersion Isotopic ratio evolution Known systematic errors cannot explain results Nor can simple, unknown systematics Iodine cell measurements planned for Keck Independent optical check required: VLT & Subaru Sleep loss? Future:
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