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Spacetime variations of physical constants can be associated with the existence of Higgs-like scalar field(s) that couple non-universally to the baryonic matter. Recent results of astronomical spectral measurements of the fractional changes in the electron-to-proton mass ratio, mu = m_e/m_p, at low (z ~ 0) and high (z ~ 6.5) redshifts are discussed. It is shown that the distribution of the most accurate estimates of Delta mu/mu = (mu_obs - mu_lab)/mu_lab ranging between z = 0 and z ~ 1100 can be approximated by a power low Delta mu/mu = k_mu (1+z)^p, with k_mu = (1.7 +/- 0.3)x10^-8 and p = 1.99 +/- 0.03, implying a dynamical nature of the scalar field(s).

We present results on numerical calculations of the sensitivity coefficients, Qmu, of microwave molecular transitions in (13C)H3OH and CH3(18O)H to the hypothetical variation in the fundamental physical constant mu - the electron-to-proton mass ratio. The invariability of mu in time and space is one of the basic assumptions of the Standard Model of particle physics which can be tested at cosmological scales by means of astronomical observations in the Galaxy and external galaxies. Our calculations show that these two methanol isotopologues can be utilized for such tests since their microwave transitions from the frequency interval 1-100 GHz exhibit a large spread in Qmu values which span a range of -109 < Qmu < 78. We show that the thermal emission lines of (13C)H3OH observed in the star-forming region NGC6334I constrain the variability of mu at a level of 3x10^-8 (1{\\sigma}), which is in line with the most stringent upper limits obtained previously from observations of methanol (CH3OH) and other molecules in the Galaxy.

Spatial and temporal variations in the electron-to-proton mass ratio, μ, and in the fine-structure constant, α, are not present in the Standard Model of particle physics but they arise quite naturally in grant unification theories, multidimensional theories and in general when a coupling of light scalar fields to baryonic matter is considered. The light scalar fields are usually attributed to a negative pressure substance permeating the entire visible Universe and known as dark energy. This substance is thought to be responsible for a cosmic acceleration at low redshifts, z < 1. A strong dependence of μ and α on the ambient matter density is predicted by chameleon-like scalar field models. Calculations of atomic and molecular spectra show that different transitions have different sensitivities to changes in fundamental constants. Thus, measuring the relative line positions, Δ V, between such transitions one can probe the hypothetical variability of physical constants. In particular, interstellar molecular clouds can be used to test the matter density dependence of μ, since gas density in these clouds is ~15 orders of magnitude lower than that in terrestrial environment. We use the best quality radio spectra of the inversion transition of NH3 (J,K)=(1,1) and rotational transitions of other molecules to estimate the radial velocity offsets, Δ V ≡ Vrot - Vinv. The obtained value of Δ V shows a statistically significant positive shift of 23±4stat±3sys m s−1 (1σ). Being interpreted in terms of the electron-to-proton mass ratio variation, this gives Δμ/μ = (22±4stat±3sys)×10−9. A strong constraint on variation of the quantity F = α2/μ in the Milky Way is found from comparison of the fine-structure transition J=1-0 in atomic carbon C i with the low-J rotational lines in carbon monoxide 13CO arising in the interstellar molecular clouds: |Δ F/F| < 3×10−7. This yields |Δ α/α| < 1.5×10−7 at z = 0. Since extragalactic absorbers have gas densities similar to those in the ISM, the values of |Δ α/α| and |Δ μ/μ| at high-z are expected to be at the same level as estimated in the Milky Way providing no temporal dependence of α and μ is present. We re-analyzed and reviewed the available optical spectra of quasars to probe Δα/α from intervening absorbers. The Fe i system at z = 0.45 towards HE 0000–2340 provides one of the best opportunities for precise measurements of Δα/α at low redshift. The current estimate is Δα/α = (7±7)×10−6. With the updated sensitivity coefficients for the Fe ii lines we re-analyzed the z = 1.84 system from the high-resolution UVES/VLT spectrum of Q 1101–264 (FWHM = 3.8 km s−1) and found Δα/α = (4.0±2.8)×10−6. The most accurate upper limit on cosmological variability of α is obtained from the Fe ii system at z = 1.15 towards the bright quasar HE 0515–4414 (V=14.9): Δα/α = (-0.12±1.79)×10−6, or |Δα/α| < 2×10−6. The limit of 2×10−6 corresponds to the utmost accuracy which can be reached with available to date optical facilities.

Microwave and far infrared (FIR) spectra of atoms and molecules are in general more sensitive to the variation of the fundamental constants than optical spectra. For example, FIR transitions between levels of the ground state multiplet 3PJ of Carbon-like ions are sensitive to α-variation, (Levshakov et al. (2008)). Moreover, sensitivities of the transitions (1-0) and (2-1) are different, (Kozlov et al. (2008)). This allows to study α-variation by comparing apparent redshifts for these two transitions of the same ion and significantly reduce systematic errors from the Doppler noise.

Far infrared fine-structure transitions of CI and CII and rotational transitions of CO are used to probe hypothetical variations of the electron-to-proton mass ratio mu = m_e/m_p at the epoch of reionization (z > 6). A constraint on Delta mu/mu = (mu_obs - mu_lab)/mu_lab = (0.7 +/- 1.2)x10^-5 (1sigma) obtained at = 6.31 is the most stringent up-to-date limit on the variation of mu at such high redshift. For all available estimates of Delta mu/mu ranging between z = 0 and z = 1100, - the epoch of recombination, - a regression curve Delta mu/mu = k_mu (1+z)^p, with k_mu = (1.6 +/- 0.3) x10^-8 and p = 2.00 +/- 0.03, is deduced. If confirmed, this would imply a dynamical nature of dark matter/dark energy.

We estimate limits on non-universal coupling of hypothetical hidden fields to standard matter by evaluating the fractional changes in the electron-to-proton mass ratio, mu = m_e/m_p, based on observations of ClassI methanol masers distributed in the Milky Way disk over the range of the galactocentric distances 4 < R < 12 kpc. The velocity offsets DeltaV = V44 - V95 measured between the 44 and 95 GHz methanol lines provide, so far, one of the most stringent constraints on the spatial gradient k_mu = d(Delta mu/mu)/dR < 2x10^-9 kpc-1 and the upper limit on Delta mu/mu < 2x10^-8, where Delta mu/mu = (mu_obs-mu_lab)/mu_lab. We also find that the offsets DeltaV are clustered into two groups which are separated by 0.022 +/- 0.003 km/s (1sigma C.L.). The grouping is most probably due to the dominance of different hyperfine transitions in the 44 and 95 GHz methanol maser emission. Which transition becomes favored is determined by an alignment (polarization) of the nuclear spins of the four hydrogen atoms in the methanol molecule. This result confirms that there are preferred hyperfine transitions involved in the methanol maser action.

(Abridged) Aims. We derive the physical properties of a filament discovered in the dark cometary-shaped cloud L1251. Methods. Mapping observations in the NH3(1,1) and (2,2) inversion lines, encompassing 300 positions toward L1251, were performed with the Effelsberg 100-m telescope at a spatial resolution of 40 arcsec and a spectral resolution of 0.045 km/s. Results. The filament L1251A consists of three condensations (alpha, beta, and gamma) of elongated morphology, which are combined in a long and narrow structure covering a 38 arcmin by 3 arcmin angular range. The opposite chirality (dextral and sinistral) of the alpha+beta and gamma condensations indicates magnetic field helicities of two types, negative and positive, which were most probably caused by dynamo mechanisms. We estimated the magnetic Reynolds number Rm > 600 and the Rossby number R < 1, which means that dynamo action is important.

The offsets between the radial velocities of the rotational transitions of carbon monoxide and the fine structure transitions of neutral and singly ionized carbon are used to test the hypothetical variation of the fine structure constant, alpha. From the analysis of the [CI] and [CII] fine structure lines and low J rotational lines of 12CO and 13CO, emitted by the dark cloud L1599B in the Milky Way disk, we find no evidence for fractional changes in alpha at the level of |\\(\\Delta \\alpha/\\alpha\\)| < 3*10^-7. For the neighbour galaxy M33 a stringent limit on Delta alpha/alpha is set from observations of three HII zones in [CII] and CO emission lines: |\\(\\Delta \\alpha/\\alpha\\)| < 4*10^-7. Five systems over the redshift interval z = 5.7-6.4, showing CO J=6-5, J=7-6 and [CII] emission, yield a limit on |\\(\\Delta \\alpha/\\alpha\\)| < 1.3*10^-5. Thus, a combination of the [CI], [CII], and CO emission lines turns out to be a powerful tool for probing the stability of the fundamental physical constants over a wide range of redshifts not accessible to optical spectral measurements.

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 |Delta alpha/alpha| < 6*10^-5 at redshifts z = 3.1 and z = 4.7.

We mapped the kinetic temperature structure of two massive star-forming regions, N113 and N159W, in the Large Magellanic Cloud (LMC). We have used \\(\\)1\\(\\,.\\!\\!^\\)6\\,(\\(\\)0.4\\,pc) resolution measurements of the para-H\\(_2\\)CO\\,\\(J_ K_ aK_c\\)\\,=\\,3\\(_03\\)--2\\(_02\\), 3\\(_22\\)--2\\(_21\\), and 3\\(_21\\)--2\\(_20\\) transitions near 218.5\\,GHz to constrain RADEX non-LTE models of the physical conditions. The gas kinetic temperatures derived from the para-H\\(_2\\)CO line ratios 3\\(_22\\)--2\\(_21\\)/3\\(_03\\)--2\\(_02\\) and 3\\(_21\\)--2\\(_20\\)/3\\(_03\\)--2\\(_02\\) range from 28 to 105\\,K in N113 and 29 to 68\\,K in N159W. Distributions of the dense gas traced by para-H\\(_2\\)CO agree with those of the 1.3\\,mm dust and Spitzer\\,8.0\\,\\(\\)m emission, but do not significantly correlate with the H\\(\\) emission. The high kinetic temperatures (\\(T_ kin\\)\\,\\(\\)\\,50\\,K) of the dense gas traced by para-H\\(_2\\)CO appear to be correlated with the embedded infrared sources inside the clouds and/or YSOs in the N113 and N159W regions. The lower temperatures (\\(T_ kin\\)\\,\\(<\\)\\,50\\,K) are measured at the outskirts of the H\\(_2\\)CO-bearing distributions of both N113 and N159W. It seems that the kinetic temperatures of the dense gas traced by para-H\\(_2\\)CO are weakly affected by the external sources of the H\\(\\) emission. The non-thermal velocity dispersions of para-H\\(_2\\)CO are well correlated with the gas kinetic temperatures in the N113 region, implying that the higher kinetic temperature traced by para-H\\(_2\\)CO is related to turbulence on a \\(\\)0.4\\,pc scale. The dense gas heating appears to be dominated by internal star formation activity, radiation, and/or turbulence. It seems that the mechanism heating the dense gas of the star-forming regions in the LMC is consistent with that in Galactic massive star-forming regions located in the Galactic plane.