Measurability of kinetic temperature from metal absorption-line spectra formed in chaotic media

We present a new method for recovering the kinetic temperature of the intervening diffuse gas to an accuracy of 10%. The method is based on the comparison of unsaturated absorption-line profiles of two species with different atomic weights. The species are assumed to have the same temperature and bulk motion within the absorbing region. The computational technique involves the Fourier transform of the absorption profiles and the consequent Entropy-Regularized chi^2-Minimization [ERM] to estimate the model parameters. The procedure is tested using synthetic spectra of CII, SiII and FeII ions. The comparison with the standard Voigt fitting analysis is performed and it is shown that the Voigt deconvolution of the complex absorption-line profiles may result in estimated temperatures which are not physical. We also successfully analyze Keck telescope spectra of CII1334 and SiII1260 lines observed at the redshift z = 3.572 toward the quasar Q1937--1009 by Tytler {\it et al.}.Comment: 25 pages, 6 Postscript figures, aaspp4.sty file, submit. Ap

Sensitivity of the H3O+ inversion-rotational spectrum to changes in m_e/m_p

Quantum mechanical tunneling inversion transition in ammonia NH3 is actively used as a sensitive tool to study possible variations of the electron-to-proton mass ratio, mu = m_e/m_p. The molecule H3O+ has the inversion barrier significantly lower than that of NH3. Consequently, its tunneling transition occurs in the far-infrared (FIR) region and mixes with rotational transitions. Several such FIR and submillimiter transitions are observed from the interstellar medium in the Milky Way and in nearby galaxies. We show that the rest-frame frequencies of these transitions are very sensitive to the variation of mu, and that their sensitivity coefficients have different signs. Thus, H3O+ can be used as an independent target to test hypothetical changes in mu measured at different ambient conditions of high (terrestrial) and low (interstellar medium) matter densities. The environmental dependence of mu and coupling constants is suggested in a class of chameleon-type scalar field models - candidates to dark energy carrier.Comment: 8 pages, 2 figures, accepted to ApJ; v2: reformatted for ApJ and discussion of systematics significantly extende

Molecular hydrogen, deuterium and metal abundances in the damped Ly-alpha system at z = 3.025 toward QSO 0347-3819

We have detected in high resolution spectra of the quasar Q0347--3819 obtained with the UVES spectrograph at the VLT/Kueyen telescope over 80 absorption features in the Lyman and Werner H2 bands at the redshift of a damped Ly-alpha system at z = 3.025. The z = 3.025 system spans over 80 km/s and exhibits a multicomponent velocity structure in the metal lines. The main component at z = 3.024855 shows a total H2 column density N(H2) = (4.10\pm0.21)*10^{14} cm^{-2} and a fractional molecular abundance f(H2) = (1.94\pm0.10)*10^{-6} derived from the H2 lines arising from J=0 to 5 rotational levels of the ground electronic-vibrational state. For the first time we unambiguously reveal a pronounced [alpha-element/iron-peak] enhancement of [O,Si/Zn] = 0.6\pm0.1 (6 sigma c.l.) at high redshift. The simultaneous analysis of metal and hydrogen lines leads to D/H = (3.75\pm0.25)*10^{-5}. This value is consistent with standard big bang nucleosynthesis if the baryon-to-photon ratio, eta, lies within the range 4.37*10^{-10} <= eta <= 5.32*10^{-10}, implying 0.016 <= Omega_b h^2_100 <= 0.020.Comment: 32 pages, 16 ps figures, accepted to Ap

Metal abundances and kinematics of quasar absorbers.- I. Absorption systems toward J2233-606

The metal line profiles of different ions observed in high HI column density systems [N(HI) > 10^{16} cm^{-2}] in quasar spectra can be used to constrain the ionization structure and kinematic characteristics of the absorbers. For these purposes, a modified Monte Carlo Inversion (MCI) procedure was applied to the study of three absorption systems in the spectrum of the HDF-South quasar J2233-606 obtained with the UVES spectrograph at the VLT/Kueyen telescope. The MCI does not confirm variations of metal abundances within separate systems which were discussed in the literature. Instead, we found that an assumption of a homogeneous metal content and a unique photoionizing background is sufficient to describe the observed complex metal profiles. It was also found that the linear size L and the line-of-sight velocity dispersion sigma_v measured within the absorbers obey a scaling relation, namely, sigma_v increases with increasing L, and that metal abundance is inversely proportional to the linear size of the system: the highest metallicity was measured in the system with the smallest L.Comment: 10 pages, 7 ps figures, accepted to A&

Fundamental physical constants at low and high redshifts

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).Comment: 7 pages, 1 figure, to be published in the proceedings of the conference `Groundbased Astronomy in Russia. XXI Century', Nizhnii Arkhyz, Karachaevo-Cherkesia, Russia, 21-25 Sep 202

A rotating helical filament in the L1251 dark cloud

(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.Comment: 21 pages, 10 figures, 1 table. Accepted for publication in A&