Dr. Nissim Kanekar
(Kapteyn Astronomical Institute)
Using OH lines to measure changes in fundamental constants - Dr. Nissim Kanekar Colloquium
I will describe a new technique to estimate variations in fundamental
constants using multiple radio OH lines. This has the advantage that all
lines arise in the same species, allowing a relatively clean comparison
between the measured redshifts. Further, the technique allows a
simultaneous measurement of changes in alpha, g_p and m_e/m_p,
using OH lines from a single object. I will also present the first
detection of the 18cm OH satellite lines at a cosmological
distance, from the z~0.25 source PKS 1413+135. The 1720 MHz
and 1620 MHz profiles are conjugate, in that the sum of their optical
depths is consistent with noise; this implies that the lines
arise in precisely the same gas. The redshifts of the line peaks are
found to agree with each other, within the error bars; this is used
to place constraints on changes in a combination of alpha, g_p and m_e/m_p over the redshift range 0 < z < 0.25.
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