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OATS-UNI/TS SEMINAR
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Speaker: Hadi Rahmani (IUCAA, Pune University, India)

Title: Constraining the variation of fundamental constants at z ~ 1.3 using 21-cm absorbers
Date: Wednesday, July 3rd, 2013
Time: 11:30
Venue: Villa Bazzoni
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Abstract: Detecting/constraining the possible time/space variations of fundamental physical quantities is an important step toward understanding the rules of nature. There have been controversial claims on the possible variation of fundamental constants of physics such as the fine structure constant, α = e2/ℏc, the proton-to-electron mass ratio, μ, over the cosmological time scales. There are also claims for the presence of spatial dipole in α. A careful independent analysis is needed confirm/refute these claims. We are addressing these issues by carefully analyzing very high resolution and high signal to noise ratio QSO spectra obtained in optical and radio wavelengths. In this talk I will present the most recent results from our ongoing study. By combining the high resolution optical spectra of five QSO observed with Very Large Telescope and very high resolution 21-cm spectra from Giant Metrewave Radio Telescope we put a stringent constraint on Δx/x to be (0.0 ± 1.5) × 10-6 at the mean redshift of = 1.36 corresponding to a look-back time of ~ 9 Gyr. Assuming the constancy of other constants, we get Δα/α = (0.0 ± 0.8) × 10-6 and Δμ/μ = (0.0 ± 1.5) × 10-6.
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Contact: Paolo Molaro (OATS)