VLT/UVES shows no cosmological variability of alpha

The cosmological variability of alpha is probed from individual observations of pairs of FeII lines. This procedure allows a better control of the systematics and avoids the influence of the spectral shifts due to ionization inhomogeneities in the absorbers and/or non-zero offsets between different exposures. Applied to the FeII lines of the metal absorption systems at zabs = 1.839 in Q1101--264 and at zabs = 1.15 in HE0515--4414 observed by means of UVES at the ESO-VLT, it provides da/a = 0.4 (+/- 1.5 stat)x10^{-6}. The result is shifted with respect to the Keck/HIRES mean da/a = -5.7(+/- 1.1 stat})x10^{-6} (Murphy et al. 2004) at a high confidence level (95%). Full details of this work are given in Levshakov et al (2005)Comment: 3 pages, 1 postscript figur

The lithium isotope ratio in the metal-poor halo star G271-162 from VLT/UVES observations

A high resolution (R = 110.000), very high S/N (>600) spectrum of the metal-poor turnoff star G271-162 has been obtained in connection with the commissioning of UVES at VLT/Kueyen. Using both 1D hydrostatic and 3D hydrodynamical model atmospheres, the lithium isotope ratio has been estimated from the LiI 670.8 nm line by means of spectral synthesis. The necessary stellar line broadening (1D: macroturbulence + rotation, 3D: rotation) has been determined from unblended KI, CaI and FeI lines. The 3D line profiles agree very well with the observed profiles, including the characteristic line asymmetries. Both the 1D and 3D analyses reveal a possible detection of 6Li in G271-162, 6Li/7Li = 0.02 +-0.01 (one sigma). It is discussed if the smaller amount of 6Li in G271-162 than in the similar halo star HD84937 could be due to differences in stellar mass and/or metallicity or whether it may reflect an intrinsic scatter of the Li isotope ratio in the ISM at a given metallicity.Comment: 5 pages with 6 figures. Accepted as a letter in A&

The cosmic microwave background radiation temperature at z = 3.025 toward QSO 0347--3819

From the analysis of the CII fine-structure population ratio in the damped Ly_alpha system at z = 3.025 toward the quasar Q0347--3819 we derive an upper bound of 14.6 (+/- 0.2) K on the cosmic microwave background temperature regardless the presence of other different excitation mechanisms. The analysis of the ground state rotational level populations of H_2 detected in the system reveals a Galactic-type UV radiation field ruling out UV pumping as an important excitation mechanism for CII. The low dust content estimated from the Cr/Zn ratio indicates that the IR dust emission can also be neglected. When the collisional excitation is considered, we measure a temperature for the cosmic background radiation of T = 12.1 (+1.7, -3.2) K. The results are in agreement with the T = 10.968 (+/-) 0.004 K predicted by the hot Big Bang cosmology at z = 3.025.Comment: Accepte

Probing 3-D matter distribution at z~2 with QSO multiple lines of sight

We investigate the 3-D matter distribution at z~2 with high resolution (R ~ 40000) spectra of QSO pairs and groups obtained with the UVES spectrograph at ESO VLT. Our sample is unique for the number density of objects and the variety of separations, between 0.5 and 7 proper Mpc. We compute the real space cross-correlation function of the Lyman-alpha forest transmitted fluxes. There is a significant clustering signal up to ~2 proper Mpc, which is still present when absorption lines with high column density (log N > 13.8) are excluded.Comment: Poster paper presented at the IAU Colloquium #199 on "Probing Galaxies through Quasar Absorption Lines" held in Shanghai, China from March 14th to 18th, 200