Indications of electron-to-proton mass ratio variations in the Galaxy. II. 3 mm methanol lines toward Sgr B2(N) and (M)

TL;DR

This study investigates potential variations in the electron-to-proton mass ratio in the Galaxy by analyzing methanol emission lines from Sgr B2(N) and (M), suggesting a possible lower value in these molecular clouds compared to laboratory measurements.

Contribution

It provides new measurements of mu variations using 3 mm methanol lines and compares these with higher frequency data, indicating potential spatial variations in fundamental constants.

Findings

Mu appears lower in Sgr B2(N) than in the lab.

Consistent negative shifts observed across different frequency ranges.

Results support the possibility of fundamental constant variations in the Galaxy.

Abstract

Differential measurements of the fundamental constant mu = m_e/m_p (the electron-to-proton mass ratio) for two sources near the Galactic Center - the Sgr B2(N) and B2(M) molecular clouds - suggest that mu is lower in these clouds than its laboratory value. Based on observations of methanol (CH3OH) emission lines in the 80-112 GHz range (data from the IRAM 30-m telescope), a weighted mean value (Delta mu/mu) = (mu_obs - mu_lab)/mu_lab = (-2.1 +/- 0.6)*10^(-7) (1 sigma) was obtained for Sgr B2(N) at the sample size n = 9. This value of (Delta mu/mu) has the same sign as the result of recent measurements of methanol lines in the higher frequency range of 542-543 GHz (data from the Herschel space telescope) for Sgr B2(N): (Delta mu/mu) = (-4.2 +/- 0.7)*10^(-7) (sample size n = 2).