LSD: Lyman-break galaxies Stellar populations and Dynamics. I: Mass, metallicity and gas at z~3.1

We present the first results of a project, LSD, aimed at obtaining spatially-resolved, near-infrared spectroscopy of a complete sample of Lyman-Break Galaxies at z~3. Deep observations with adaptive optics resulted in the detection of the main optical lines, such as [OII], Hbeta and [OIII], which are used to study sizes, SFRs, morphologies, gas-phase metallicities, gas fractions and effective yields. Optical, near-IR and Spitzer/IRAC photometry is used to measure stellar mass. We obtain that morphologies are usually complex, with the presence of several peaks of emissions and companions that are not detected in broad-band images. Typical metallicities are 10-50% solar, with a strong evolution of the mass-metallicity relation from lower redshifts. Stellar masses, gas fraction, and evolutionary stages vary significantly among the galaxies, with less massive galaxies showing larger fractions of gas. In contrast with observations in the local universe, effective yields decrease with stellar mass and reach solar values at the low-mass end of the sample. This effect can be reproduced by gas infall with rates of the order of the SFRs. Outflows are present but are not needed to explain the mass-metallicity relation. We conclude that a large fraction of these galaxies are actively creating stars after major episodes of gas infall or merging.Comment: MNRAS, in pres

The Richness and Beauty of the Physics of Cosmological Recombination: The Contributions from Helium

The physical ingredients to describe the epoch of cosmological recombination are amazingly simple and well-understood. This fact allows us to take into account a very large variety of processes, still finding potentially measurable consequences. In this contribution we highlight some of the detailed physics that were recently studied in connection with cosmological hydrogen and helium recombination. The impact of these considerations is two-fold: (i) the associated release of photons during this epoch leads to interesting and unique deviations of the Cosmic Microwave Background (CMB) energy spectrum from a perfect blackbody, which, in particular at decimeter wavelength, may become observable in the near future. Despite the fact that the abundance of helium is rather small, it also contributes a sizeable amount of photons to the full recombination spectrum, which, because of differences in the dynamics of the helium recombinations and the non-trivial superposition of all components, lead to additional distinct spectral features. Observing the spectral distortions from the epochs of hydrogen and helium recombination, in principle would provide an additional way to determine some of the key parameters of the Universe (e.g. the specific entropy, the CMB monopole temperature and the pre-stellar abundance of helium), not suffering from limitations set by cosmic variance. Also it permits us to confront our detailed understanding of the recombination process with direct observational evidence. (ii) with the advent of high precision CMB data, e.g. as will be available using the Planck Surveyor or CMBpol, a very accurate theoretical understanding of the ionization history of the Universe becomes necessary for the interpretation of the CMB temperature and polarization anisotropies. (abridged)Comment: 16 pages, 11 figures, proceedings of the conference: "A Century of Cosmology: Past, Present and Future

The quasar M_bh - M_host relation through Cosmic Time I - Dataset and black hole masses

We study the M_bh - M_host relation as a function of Cosmic Time in a sample of 96 quasars from z=3 to the present epoch. In this paper we describe the sample, the data sources and the new spectroscopic observations. We then illustrate how we derive M_bh from single-epoch spectra, pointing out the uncertainties in the procedure. In a companion paper, we address the dependence of the ratio between the black hole mass and the host galaxy luminosity and mass on Cosmic Time.Comment: 16 pages, 6 figures, 5 tables. Accepted for publication in MNRA

Novel opsin gene variation in large-bodied, diurnal lemurs

Some primate populations include both trichromatic and dichromatic (red-green colour blind) individuals due to allelic variation at the X-linked opsin locus. This polymorphic trichromacy is well described in day-active New World monkeys. Less is known about colour vision in Malagasy lemurs, but, unlike New World monkeys, only some day-active lemurs are polymorphic, while others are dichromatic. The evolutionary pressures underlying these differences in lemurs are unknown, but aspects of species ecology, including variation in activity pattern, are hypothesized to play a role. Limited data on X-linked opsin variation in lemurs make such hypotheses difficult to evaluate. We provide the first detailed examination of X-linked opsin variation across a lemur clade (Indriidae). We sequenced the X-linked opsin in the most strictly diurnal and largest extant lemur, Indri indri, and nine species of smaller, generally diurnal indriids (Propithecus). Although nocturnal Avahi (sister taxon to Propithecus) lacks a polymorphism, at least eight species of diurnal indriids have two or more X-linked opsin alleles. Four rainforest-living taxa-I. indri and the three largest Propithecus species-have alleles not previously documented in lemurs. Moreover, we identified at least three opsin alleles in Indri with peak spectral sensitivities similar to some New World monkeys

Geographical patterns of deep mitochondrial differentiation in widespread Malagasy reptiles

Using sequences of the mitochondrial 16S rRNA gene, we reconstructed the phylogeography of six widely distributed Malagasy reptiles: two gekkonid lizard species, Phelsuma lineata and Hemidactylus mercatorius; two chameleons, the Calumma brevicorne complex, and Furcifer lateralis; and two skinks, Trachylepis gravenhorstii and Trachylepis elegans. Genetic differentiation among major haplotype lineages was high and in some cases indicates or confirms species status of the divergent populations. Maximum uncorrected sequence divergences were between 2.2% and 8.3% within the various species or species complexes. Haplotype lineages were exclusive to geographic regions, except in the commensal H. mercatorius where in three anthropogenic habitats coexistence of haplotype lineages was observed, possibly due to human translocation. The eastward flowing rivers Mangoro and Mananara may represent barriers to gene flow in the case of three species each. Some species sampled from humid eastern and arid western Madagascar showed no differentiation between populations from these two regions; instead the pattern observed was in several cases more concordant with a differentiation along a north-south axis

The measurement of the noise-equivalent spectral radiance of SIMBIO-SYS/VIHI spectrometer

We report about the measurement of the Noise- Equivalent Spectral Radiance (NESR) of the VIHI imaging spectromter aboard ESA's Bepi Colombo mission to Mercury. The knowledge of the NESR allows to determine the capability of an optical detector to measure faint signals. A description of the setup used to determine the NESR during the prelaunch calibration campaign is given. The processing of the data col- lected at various operative temperatures and integration times is described. The sensitivity study of the NESR has been performed at the expected detector's temperatures and integration times with the goal to determine the minimum spectral radiance at which VIHI is sensitive during the different observation phases of the mission. A simulation of the expected Signal-to-Noise Ratio (SNR) of VIHI during the different orbital phases is provided

On species delimitation: Yet another lemur species or just genetic variation?

<p>Abstract</p> <p>Background</p> <p>Although most taxonomists agree that species are independently evolving metapopulation lineages that should be delimited with several kinds of data, the taxonomic practice in Malagasy primates (Lemuriformes) looks quite different. Several recently described lemur species are based solely on evidence of genetic distance and diagnostic characters of mitochondrial DNA sequences sampled from a few individuals per location. Here we explore the validity of this procedure for species delimitation in lemurs using published sequence data.</p> <p>Results</p> <p>We show that genetic distance estimates and <it>Population Aggregation Analysis </it>(PAA) are inappropriate for species delimitation in this group of primates. Intra- and interspecific genetic distances overlapped in 14 of 17 cases independent of the genetic marker used. A simulation of a fictive taxonomic study indicated that for the mitochondrial D-loop the minimum required number of individuals sampled per location is 10 in order to avoid false positives via PAA.</p> <p>Conclusions</p> <p>Genetic distances estimates and PAA alone should not be used for species delimitation in lemurs. Instead, several nuclear and sex-specific loci should be considered and combined with other data sets from morphology, ecology or behavior. Independent of the data source, sampling should be done in a way to ensure a quantitative comparison of intra- and interspecific variation of the taxa in question. The results of our study also indicate that several of the recently described lemur species should be reevaluated with additional data and that the number of good species among the currently known taxa is probably lower than currently assumed.</p