Poster
Abstract :
In about six refereed papers
[7][10][12][13][14][15], I investigated
the value of nature’s fundamental
couplings in the early universe,
considering possible deviations from the
current standard values. A time varying
fine structure constant can leave an
imprint on CMB anisotropies by changing
the time of recombination and the size
of the acoustic horizon at
photon-electron decoupling (see
[1],[2],[3],[4]). The CMB datasets have
been extensively used to constrain α by
parametraizing a variation in the fine
structure constant as Δα = (α - α0)∕α0, where α0 is the standard, local value
and α is the value during the
recombination process[5],[6]. By
performing a MCMC analysis and using
WMAP-5 years data, and I found α∕α0 = 0.998 ± 0.021 at 68%
c.l., the constraints are much tighter
if you also include all the CMB data
plus a prior on the value of Hubble
constant, in this case I found α∕α0 = 1.001 ± 0.007 [7].
By including early dark energy component
[11], the variations of the fine
structure constant using WMAP-7 years
data and HST data give α∕α0 = 0.963 ± 0.044, Ωe
< 0.064 and for the coupling ζ <
0.047 at 95%c.l.. By performing a Fisher
matrix analysis and using Planck and
CMBPol experimental specifications I
found better and strong constraints on
the parameter: for Planck σ(α∕α0) = 0.0012, σ(Ωe) = 0.0036, σ(ζ) < 0.0012 and the results for
CMBPol σ(α∕α0) = 0.00025, σ(Ωe) = 0.0015 and σ(ζ) < 0.00022 [12]. |
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- [11] Erminia
Calabrese, Roland de Putter, Dragan
Huterer, Eric V. Linder, Alessandro
Melchiorri. Phys.Rev.D83:023011,2011
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Calabrese, Eloisa Menegoni, C.J.A.P.
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”‘Constraints on the dark energy
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varying fine structure constant”’
(IJMPD, International Journal of
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pp. 507-512 2010). E. Menegoni, S.
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- [14] ”The
Fine Structure Constant and the CMB
Damping Scale”, Eloisa Menegoni, Maria
Archidiacono, Erminia Calabrese,
Silvia Galli, C. J. A. P. Martins,
Alessandro Melchiorri. Cite as:
arXiv:1202.1476v1 [astro-ph.CO].
- [15] ”Future
constraints on variations of the fine
structure constant from combined CMB
and weak lensing measurements” Matteo
Martinelli, Eloisa Menegoni,
Alessandro Melchiorri. Cite as:
arXiv:1202.4373v2 [astro-ph.CO].
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