H. Rahmani

The UVES Large Program for testing fundamental physics I. Bounds on a change in alpha towards quasar HE 2217-2818

Context. Absorption-line systems detected in quasar spectra can be used to compare the value of the fine-structure constant, , measured today on Earth with its value in distant galaxies. In recent years, some evidence has emerged of small temporal and also spatial variations in on cosmological scales. These variations may reach a fractional level of 10 ppm (parts per million). Aims. To test these claims we are conducting a Large Program of observations with the Very Large Telescope’s Ultraviolet and Visual Echelle Spectrograph (UVES), and are obtaining high-resolution (R 60 000) and high signal-to-noise ratio (S=N 100) UVES spectra calibrated specifically for this purpose. Here we analyse the first complete quasar spectrum from this programme, that of HE 2217 2818. Methods. We applied the many multiplet method to measure in five absorption systems towards this quasar: zabs = 0:7866, 0.9424, 1.5558, 1.6279 , and 1.6919. Results. The most precise result is obtained for the absorber at zabs = 1:6919 where 3 Feii transitions and Alii 1670 have high S/N and provide a wide range of sensitivities to . The absorption profile is complex with several very narrow features, and it requires 32 velocity components to be fitted to the data. We also conducted a range of tests to estimate the systematic error budget. Our final result for the relative variation in in this system is = = +1:3 2:4stat 1:0sys ppm. This is one of the tightest current bounds on -variation from an individual absorber. A second, separate approach to the data reduction, calibration, and analysis of this system yielded a slightly di erent result of 3.8 2:1stat ppm, possibly suggesting a larger systematic error component than our tests indicated. This approach used an additional 3 Feii transitions, parts of which were masked due to contamination by telluric features. Restricting this analysis to the Feii transitions alone and using a modified absorption profile model gave a result that is consistent with the first approach, = = +1:1 2:6stat ppm. The four other absorbers have simpler absorption profiles, with fewer and broader features, and o er transitions with a narrower range of sensitivities to . They therefore provide looser bounds on = at the > 10 ppm precision level.

METALLICITIES, DUST, AND MOLECULAR CONTENT OF A QSO-DAMPED Lyα SYSTEM REACHING log N(H I) = 22: AN ANALOG TO GRB-DLAs

We present the elemental abundance and H2 content measurements of a damped Lyα (DLA) system with an extremely large H I column density, log N(H I) (cm–2) = 22.0 ± 0.10, at z abs = 3.287 toward the QSO SDSS J081634+144612. We measure column densities of H2, C I, C I , Zn II, Fe II, Cr II, Ni II, and Si II from a high signal-to-noise and high spectral resolution VLT-UVES spectrum. The overall metallicity of the system is [Zn/H] = –1.10 ± 0.10 relative to solar. Two molecular hydrogen absorption components are seen at z = 3.28667 and 3.28742 (a velocity separation of ≈52 km s–1) in rotational levels up to J = 3. We derive a total H2 column density of log N(H2) (cm–2) = 18.66 and a mean molecular fraction of f = 2N(H2)/[2N(H2) + N(H I)] = 10–3.04 ± 0.37, typical of known H2-bearing DLA systems. From the observed abundance ratios we conclude that dust is present in the interstellar medium of this galaxy, with an enhanced abundance in the H2-bearing clouds. However, the total amount of dust along the line of sight is not large and does not produce any significant reddening of the background QSO. The physical conditions in the H2-bearing clouds are constrained directly from the column densities of H2 in different rotational levels, C I and C I . The kinetic temperature is found to be T ≈ 75 K and the particle density lies in the range n H = 50-80 cm–3. The neutral hydrogen column density of this DLA is similar to the mean H I column density of DLAs observed at the redshift of γ-ray bursts (GRBs). We explore the relationship between GRB-DLAs and the high column density end of QSO-DLAs finding that the properties (metallicity and depletion) of DLAs with log N(H I) > 21.5 in the two populations do not appear to be significantly different.

A study of low-metallicity DLAs at high redshift and C ii* as a probe of their physical conditions

We present a detailed high spectral resolution (R

The UVES Large Program for testing fundamental physics – III. Constraints on the fine-structure constant from three telescopes

\sim

Parsec-scale structures and diffuse bands in a translucent interstellar medium at z 0.079

40000) study of five high-z damped Lyman

Constraining the variation of fundamental constants at z ∼ 1.3 using 21-cm absorbers

\alpha

The star formation history of mass-selected galaxies from the VIDEO survey

systems (DLAs) and one sub-DLA detected along four QSO sightlines. Four of these DLAs are very metal-poor with [Fe/H]

Fundamental constants and high resolution spectroscopy

\le

Constraining the variation in the fine-structure constant using SDSS DR7 quasi-stellar object spectra

-