Related papers: Limits on the spatial variations of the electron-t…
We report on new tests that improve our previous (2009-2010) estimates of the electron-to-proton mass ratio variation, mu = m_e/m_p. Subsequent observations (2011-2013) at the Effelsberg 100-m telescope of a sample of eight molecular cores…
The ammonia method to probe variations of the electron-to-proton mass ratio, Delta_mu/mu, is applied for the first time to dense prestellar molecular clouds in the Milky Way. Carefully selected sample of 21 NH_3/CCS pairs observed in the…
(Abridged) Radio-astronomical observations of molecular cores in lines of NH3 (J,K)=(1,1), CCS J_N=2_1-1_0, HC3N J=5-4, and N2H+ J=1-0 are used to measure the relative radial velocity offsets, Delta V, between the NH3 (1,1) and other…
(Abridged) In our previous work we found a statistically significant offset Delta V = 27 m/s between the radial velocities of the HC3N(2-1) and NH3(1,1) transitions observed in molecular cores from the Milky Way. This may indicate that the…
(Abridged) The ammonia method, which has been proposed to explore the electron-to-proton mass ratio, mu = m_e/m_p, is applied to nearby dark clouds in the Milky Way. This ratio, which is measured in different physical environments of high…
The Standard Model of particle physics assumes that the so-called fundamental constants are universal and unchanging. Absorption lines arising in molecular clouds along quasar sightlines offer a precise test for variations in the…
Spatial and temporal variations in the electron-to-proton mass ratio, mu, and in the fine-structure constant, alpha, are predicted in non-Standard models aimed to explain the nature of dark energy. Among them the so-called chameleon-like…
We report on the using of torsion-rotational transitions in the CH3OH and (13)CH3OH molecules to evaluate possible variations of the physical constant mu=m_e/m_p - the electron-to-proton mass ratio - from spectral observations of emission…
(Abridged) A procedure is suggested to explore the value of F = alpha^2/mu, where mu = m_e/m_p is the electron-to-proton mass ratio, and alpha is the fine-structure constant. The fundamental physical constants, which are measured in…
In this paper, we show that methanol (CH3OH) torsional-rotational transitions, which have increased sensitivity to small variations of mu - the electron-to-proton mass ratio, are shifted relative to less sensitive transitions in the…
Exotic cosmologies predict variability of the fundamental physical constants over the cosmic time. Using the VLT/UVES high resolution spectra of the quasar Q0347-3819 and unblended electronic - vibrational - rotational lines of the H2…
In an effort to resolve the discrepancy between two measurements of the fundamental constant mu, the proton to electron mass ratio, at early times in the universe we reanalyze the same data used in the earlier studies. Our analysis of the…
We present the quantum-mechanical calculations of the dimensionless sensitivity coefficients Q to small changes in the fundamental physical constant mu = m_e/m_p - the electron-to-proton mass ratio - for a number of low-frequency (1-50 GHz)…
Using the 32-m Medicina, 45-m Nobeyama, and 100-m Effelsberg telescopes we found a statistically significant velocity offset Delta V = 27 +/- 3 m/s (1sigma) between the inversion transition in NH3(1,1) and low-J rotational transitions in…
Based on measurements with the Effelsberg 100-m telescope, a multi-line study of molecular species is presented toward the gravitational lens system PKS1830-211. Obtaining average radial velocities and performing Large Velocity Gradient…
The variation of the dimensionless fundamental physical constant mu = m_p/m_e (the proton to electron mass ratio) can be constrained via observation of Lyman and Werner lines of molecular hydrogen in the spectra of damped Lyman alpha…
This article summarizes the latest results on the proton-to-electron mass ratio $\mu$ derived from H$_2$ observations at high redshift in the light of possible variations of fundamental physical constants. The focus lies on UVES…
We determine the sensitivity to a possible variation of the proton-to-electron mass ratio \mu for torsion-wagging-rotation transitions in the ground state of methylamine (CH3NH2). Our calculation uses an effective Hamiltonian based on a…
We report deep Green Bank Telescope (GBT) spectroscopy in the redshifted NH$_3$~(1,1), CS~1-0 and H$_2$CO~0$_{\rm 00}$-1$_{\rm 01}$ lines from the $z \sim 0.685$ absorber towards B0218+357. The inversion (NH$_3$) and rotational (CS,…
Near (~100 pc) and far (~8.7 kpc) relative to the Galactic center, the molecular clouds SgrB2(N) and Orion-KL exhibit different values of the fundamental physical constant mu=m_e/m_p - the electron-to-proton mass ratio. Measured frequency…