The use of OH ‘main’ lines to constrain the variation of fundamental constants

Kanekar, Nissim ; Chengalur, J. N. (2004) The use of OH ‘main’ lines to constrain the variation of fundamental constants Monthly Notices of the Royal Astronomical Society, 350 (1). L17-L20. ISSN 0035-8711

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We describe a new technique to measure variations in the fundamental parameters α and y≡me/mp, using the sum of the frequencies of cm‐wave OH ‘main’ lines. The technique is ∼ three orders of magnitude more sensitive than that of Chengalur & Kanekar, which utilized only the four 18‐cm OH lines. The increase in sensitivity stems from the use of OH ‘main’ lines arising from different rotational states, instead of the frequency difference between lines from the same state. We also show that redshifts of the main OH 18‐ and 6‐cm lines can be combined with the redshift of an HCO+ transition to measure any evolution in α and y. Both 18‐cm main lines and a number of HCO+ lines have already been detected in absorption in four cosmologically distant systems; the detection of the main 6‐cm OH line in any of these systems would thus be sufficient to simultaneously constrain changes in α and y between the absorption redshift and today.

Item Type:Article
Source:Copyright of this article belongs to Oxford University Press.
Keywords:Line: Profiles; Techniques: Spectroscopic; Radio Lines: General.
ID Code:118124
Deposited On:14 May 2021 07:01
Last Modified:14 May 2021 07:01

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