SpaceTime evolution of the fine structure constant

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SpaceTime evolution of the fine structure constant
Collaborators John Barrow, Cambridge Chris
Churchill, Penn. State Francois Combes, Obs.
Paris Steve Curran, UNSW Michael
Drinkwater, U Melb. Vladimir Dzuba, UNSW
Victor Flambaum, UNSW Jason Prochaska, OCIW
Wallace Sargent, Caltech Rob Simcoe, Caltech
John Webb, UNSW Tommy Wiklind, OSO Arthur
Wolfe, UCSD
Special thanks to Ulf Griesmann, NIST
Sveneric Johansson, Lund U. Rainer Kling,
NIST Richard Learner, IC Ulf Litzén, Lund
U. Juliet Pickering, IC Anne Thorne,
IC for dedicated laboratory measurements
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Outline

• Motivations for a varying ae2/hc
• Limits on Da/a
• Laboratory
• Oklo fission reactor
• QSO absorption systems
• The old alkali doublet (AD) method
• The new many-multiplet (MM) method
• Our recent results A non-zero Da/a?

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Motivations for varying constants

• Modern unified theories (e.g. String/M-theory)
  invoke extra spatial dimensions.
• Our (31)-dimensional constants related to scale
  sizes of extra dimensions.
• M-theory gravity acts in all 11 dimensions but
  other forces (EM, strong, weak) act only in
  4-dimensions.
• Expect variations in G on small (0.1mm) scales.

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Motivations for varying constants

• Varying c theories can solve cosmological
  problems (e.g. horizon problem ? smaller ae2/hc
  in the past).
• Bekensteins (1982) varying-e theory spacetime
  variations of a scalar field drive variations in
  e.
• Sandvik, Barrow Magueijo (2001) Bekensteins
  theory cosmology ? predictions of cosmological
  variations in a.

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Limits on Da/a laboratory

• Atomic clocks relativistic corrections are of
  order (Za)2.
• Prestage et al. (1995) compared Hydrogen maser
  and Mercury clocks Da/a ? 1.410-14 over 140
  days (assumes gp/gHg constant).
• Sortais et al. (2001) compared Rubidium and
  Cesium clocks Da/a (0.8 1.4)10-14 over 2
  years (assumes gRb/gCe constant).
• Clocks with similar Z can constrain varying
  g-factors (e.g. Godone et al. 1993). Stability
  advantage.

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Limits on Da/a Oklo
http//www.curtin.edu.au/curtin/centre/waisrc/OKLO
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Limits on Da/a Oklo

• Heavy nuclei (e.g. Sm) have sharp resonances in
  their neutron absorption cross-section ?
• Sm isotopic abundances ? 149Sm neutron absorption
  cross section ? neutron capture resonance energy
  ? Da/a.
• 1976 Shlyakhter first analyzed Sm abundances
  from Oklo to constrain Da/a.
• 1996 Damour Dyson re-analyzed the same data to
  obtain a stronger constraint Da/a
• 2000 Fujii et al. find Da/a(-0.040.15)10-7
  from new data.

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QSO absorption lines
Quasar
To Earth
Lyaem
CIV
SiII
SiIV
CII
SiII
Lyman limit
Lya
Lyb
Lybem
NVem
Lya forest
CIVem
SiIVem
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QSO absorption lines

• A Keck/HIRES doublet

Quasar Q175975
H emission
Over 60 000 data points!
Separation ? a2
H absorption
C IV doublet
Metal absorption
C IV 1550Å
C IV 1548Å
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The alkali doublet (AD) method

• 1976 Wolfe, Brown Roberts first applied the AD
  method to intervening Mg II absorption lines.
• 2000 Varshalovich et al. recently obtained
  Da/a(-4.6 4.3 1.4)10-5 using the AD method
  with 16 Si IV absorption systems (zavg2.6).
• 2001 We have used improved lab wavelengths and
  new data from Keck to findDa/a(-0.5 1.3)10-5
  (zavg2.8).

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The alkali doublet (AD) method

• The AD method is simple but inefficient.
• The common S ground state in ADs has maximal
  relativistic corrections!

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The many-multiplet (MM) method

• Relativistic corrections for many-electron atoms

• Compare light (Z10) and heavy (Z30) ions OR
• S ? P and D ? P transitions in heavy ions.
• More formally, we write the transition frequency
  as wzw0qx for x(az/a0)2 1.
• We must calculate q and measure w0.

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Low-z vs. High-z constraints
Low-z (0.5 1.8)
High-z (1.8 3.5)
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Low-z vs. High-z constraints
High-z
Low-z
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Current results
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Potential systematic effects

• Laboratory wavelength errors
• Heliocentric velocity variation
• Temperature changes during observations
• Line blending
• Differential isotopic saturation
• Hyperfine structure effects
• Instrumental profile variations
• and of course, Magnetic fields

• Wavelength calibration errors

• Atmospheric refraction effects
• Isotopic ratio evolution

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Radio constraints H I 21-cm vs. mm

• Hydrogen hyperfine transition at lH 21cm.
• Molecular rotational transitions CO, HCO, HCN,
  HNC, CN, CS etc. in the mm-band.
• wH/wM ? a2gP where gP is the proton magnetic
  g-factor.

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All current constraints
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Conclusions

• 3 independent optical samples now agree!
• There IS an effect in the data but is it a
  varying a or just undiscovered systematic
  effects?
• Must get spectra from different telescope ? UVES!
• Must also find more H I 21cm/mm absorbers.
• Potential constraints from combining optical
  spectra and H I 21cm spectra ( 5 good
  candidates).
• Higher-z tests CMB and BBN constraints (1
  precision).