Fine-structure transitions as a tool for studying variation of α at high redshifts

S. A. Levshakov1,3,4, M. G. Kozlov2,3

1Ioffe Institute, Politekhnicheskaya 26, 194021 Saint Petersburg, Russia
2Petersburg Nuclear Physics institute, 188300 Gatchina, Russia
3St. Petersburg Electrotechnical University "LETI", Prof. Popov Str. 5, 197376, St. Petersburg, Russia
4ITMO University, 191002 St. Petersburg, Russia

Star-forming galaxies at high redshifts are the ideal targets to probe the hypothetical variation of the fine-structure constant alpha over cosmological time scales. We propose a modification of the alkali doublets method which allows us to search for variation in alpha combining far infrared and submillimeter spectroscopic observations. This variation manifests as velocity offsets between the observed positions of the fine-structure and gross-structure transitions when compared to laboratory wavelengths. Here we describe our method whose sensitivity limit to the fractional changes in alpha is about 5×10-7. We also demonstrate that current spectral observations of hydrogen and [C II] 158 micron lines provide an upper limit on |Δα/α| < 6×10-5 at redshifts z = 3.1 and z = 4.7.



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