Spectroscopic reassignment and ground state dissociation energy of molecular iodine

Spectroscopic reassignment and ground state dissociation energy of molecular iodin

Permeability of a one-dimensional potential barrier

Permeability of one dimensional potential barrie

Dissociation energy and long-range potential of diatomic molecules from vibrational spacings - The halogens

Dissociation energy and long-range potential of diatomic molecules from vibrational spacings, halogen

Shape resonances and rotationally predissociating levels - The atomic collision time delay functions and quasibound level properties of H2 /Chi /1 Sigma g plus//

Atomic collision time delay functions and quasibound level properties of ground state of molecular hydroge

Sticky Particles and Stochastic Flows

Gaw\c{e}dzki and Horvai have studied a model for the motion of particles carried in a turbulent fluid and shown that in a limiting regime with low levels of viscosity and molecular diffusivity, pairs of particles exhibit the phenomena of stickiness when they meet. In this paper we characterise the motion of an arbitrary number of particles in a simplified version of their model

Foot-operated cell-counter

Cell-counter for cell indices consists of a footboard with four pressure sensitive switches and an enclosure for the components and circuitry. This device increases the operators efficiency by reducing the number of required hand movements

Very High-Redshift Lensed Galaxies

We review in this paper the main results recently obtained on the identification and study of very high-z galaxies usinglensing clusters as natural gravitational telescopes. We present in detail our pilot survey with ISAAC/VLT, aimed at the detection of z>7 sources. Evolutionary synthesis models for extremely metal-poor and PopIII starbursts have been used to derive the observational properties expected for these high-z galaxies, such as expected magnitudes and colors, line fluxes for the main emission lines, etc. These models have allowed to define fairly robust selection criteria to find z~7-10 galaxies based on broad-band near-IR photometry in combination with the traditional Lyman drop-out technique. The first results issued from our photometric and spectroscopic survey are discussed, in particular the preliminary confirmation rate, and the global properties of our high-z candidates, including the latest results on the possible z=10.0 candidate A1835-1916. The search efficiency should be significantly improved by the future near-IR multi-object ground-based and space facilities. However, strong lensing clusters remain a factor of ~5-10 more efficient than blank fields in this redshift domain, within the FOV of a few arcminutes around the cluster core, for the typical depth required for this survey project.Comment: 14 pages, 7 figures, Proceedings of IAU Symposium No. 225: The Impact of Gravitational Lensing on Cosmology, Y. Mellier and G. Meylan, Ed

The ionization fraction gradient across the Horsehead edge: An archetype for molecular clouds

The ionization fraction plays a key role in the chemistry and dynamics of molecular clouds. We study the H13CO+, DCO+ and HOC+ line emission towards the Horsehead, from the shielded core to the UV irradiated cloud edge, i.e., the Photodissociation Region (PDR), as a template to investigate the ionization fraction gradient in molecular clouds. We analyze a PdBI map of the H13CO+ J=1-0 line, complemented with IRAM-30m H13CO+ and DCO+ higher-J line maps and new HOC+ and CO+ observations. We compare self-consistently the observed spatial distribution and line intensities with detailed depth-dependent predictions of a PDR model coupled with a nonlocal radiative transfer calculation. The chemical network includes deuterated species, 13C fractionation reactions and HCO+/HOC+ isomerization reactions. The role of neutral and charged PAHs in the cloud chemistry and ionization balance is investigated. The detection of HOC+ reactive ion towards the Horsehead PDR proves the high ionization fraction of the outer UV irradiated regions, where we derive a low [HCO+]/[HOC+]~75-200 abundance ratio. In the absence of PAHs, we reproduce the observations with gas-phase metal abundances, [Fe+Mg+...], lower than 4x10(-9) (with respect to H) and a cosmic-rays ionization rate of zeta=(5+/-3)x10(-17) s(-1). The inclusion of PAHs modifies the ionization fraction gradient and increases the required metal abundance. The ionization fraction in the Horsehead edge follows a steep gradient, with a scale length of ~0.05 pc (or ~25''), from [e-]~10(-4) (or n_e ~ 1-5 cm(-3)) in the PDR to a few times ~10(-9) in the core. PAH^- anions play a role in the charge balance of the cold and neutral gas if substantial amounts of free PAHs are present ([PAH] >10(-8)).Comment: 13 pages, 7 figures, 6 tables. Accepted for publication in A&A (english not edited

Adaptive Optics observations of LBQS 0108+0028: K-band detection of the host galaxy of a radio-quiet QSO at z=2

We report the first unambiguous detection of the host galaxy of a normal radio-quiet QSO at high-redshift in K-band. The luminosity of the host comprises about 35% of the total K-band luminosity. Assuming the average colour of QSOs at z=2, the host would be about 5 to 6 mag brighter than an unevolved L* galaxy placed at z=2, and 3 to 4 mag brighter than a passively evolved L* galaxy at the same redshift. The luminosity of the host galaxy of the QSO would thus overlap with the highest found in radio-loud QSOs and radio-galaxies at the same redshift.Comment: Accepted to be published in MNRAS. 4 pages, 2 postscript figures. Also available at http://www.mpa-garching.mpg.de/~itzia