Does the fine structure constant vary?: A detailed investigation into systematic errors
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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:
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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-removalPost-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
FeIIPositiveMediocre
Anchor
MediocreNegative
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: