The 1000 brightest hipass galaxies: The H I mass function and Omega(H I)

We present a new, accurate measurement of the H I mass function of galaxies from the HIPASS Bright Galaxy Catalog, a sample of 1000 galaxies with the highest H I peak flux densities in the southern (delta

CONSTRAINING THE NONEXTENSIVE MASS FUNCTION OF HALOS FROM BAO, CMB AND X-RAY DATA

Clusters of galaxies are the most impressive gravitationally-bound systems in the universe, and their abundance (the cluster mass function) is an important statistic to probe the matter density parameter (Omega(m)) and the amplitude of density fluctuations (sigma(8)). The cluster mass function is usually described in terms of the Press-Schecther (PS) formalism where the primordial density fluctuations are assumed to be a Gaussian random field. In previous works we have proposed a non-Gaussian analytical extension of the PS approach with basis on the q-power law distribution (PL) of the nonextensive kinetic theory. In this paper, by applying the PL distribution to fit the observational mass function data from X-ray highest flux-limited sample (HIFLUGCS), we find a strong degeneracy among the cosmic parameters, sigma(8), Omega(m) and the q parameter from the PL distribution. A joint analysis involving recent observations from baryon acoustic oscillation (BAO) peak and Cosmic Microwave Background (CMB) shift parameter is carried out in order to break these degeneracy and better constrain the physically relevant parameters. The present results suggest that the next generation of cluster surveys will be able to probe the quantities of cosmological interest (sigma(8), Omega(m)) and the underlying cluster physics quantified by the q-parameter.

The core mass function in star-forming region NGC6357

The aim of this work was to study the dense cloud structures and to obtain the mass distribution of the dense cores (CMF) within the NGC6357 complex, from observations of the dust continuum at 450 and 850~$\mu$m of a 30 $\times$ 30 arcmin$^2$ region containing the H\textsc{ii} regions, G353.2+0.9 and G353.1+0.6.

Traffic controls for construction and maintenance work zones. Volume I - office function.

Federal Highway Administration, Washington, D.C.

Memoiren des Admirals A. Schischkow: über die Zeit seines Aufenthalts bei der Person des wohlseligen Kaisers Alexander I (in Function eines Staatssecretärs) während des Krieges mit den Franzosen in den Jahren 1812 bis 1814 /

Mode of access: Internet.

The 1000 brightest HIPASS galaxies H I properties

We present the HIPASS Bright Galaxy Catalog (BGC), which contains the 1000 H I brightest galaxies in the southern sky as obtained from the H i Parkes All-Sky Survey ( HIPASS). The selection of the brightest sources is based on their H I peak flux density (S-peak greater than or similar to116 mJy) as measured from the spatially integrated HIPASS spectrum. The derived H I masses range from similar to10(7) to 4 x 10(10) M-.. While the BGC ( z< 0.03) is complete in S-peak, only a subset of &SIM;500 sources can be considered complete in integrated H I flux density (F-H I &GSIM;25 Jy km s(-1)). The HIPASS BGC contains a total of 158 new redshifts. These belong to 91 new sources for which no optical or infrared counterparts have previously been cataloged, an additional 51 galaxies for which no redshifts were previously known, and 16 galaxies for which the cataloged optical velocities disagree. Of the 91 newly cataloged BGC sources, only four are definite H I clouds: while three are likely Magellanic debris with velocities around 400 km s(-1), one is a tidal cloud associated with the NGC 2442 galaxy group. The remaining 87 new BGC sources, the majority of which lie in the zone of avoidance, appear to be galaxies. We identified optical counterparts to all but one of the 30 new galaxies at Galactic latitudes > 10degrees. Therefore, the BGC yields no evidence for a population of free-floating'' intergalactic H I clouds without associated optical counterparts. HIPASS provides a clear view of the local large-scale structure. The dominant features in the sky distribution of the BGC are the Supergalactic Plane and the Local Void. In addition, one can clearly see the Centaurus Wall, which connects via the Hydra and Antlia Clusters to the Puppis Filament. Some previously hardly noticable galaxy groups stand out quite distinctly in the H I sky distribution. Several new structures, including some not behind the Milky Way, are seen for the first time.

The death of massive stars - I. Observational constraints on the progenitors of Type II-P supernovae

We present the results of a 10.5-yr, volume-limited (28-Mpc) search for supernova (SN) progenitor stars. In doing so we compile all SNe discovered within this volume (132, of which 27 per cent are Type Ia) and determine the relative rates of each subtype from literature studies. The core-collapse SNe break down into 59 per cent II-P and 29 per cent Ib/c, with the remainder being IIb (5 per cent), IIn (4 per cent) and II-L (3 per cent). There have been 20 II-P SNe with high-quality optical or near-infrared pre-explosion images that allow a meaningful search for the progenitor stars. In five cases they are clearly red supergiants, one case is unconstrained, two fall on compact coeval star clusters and the other twelve have no progenitor detected. We review and update all the available data for the host galaxies and SN environments (distance, metallicity and extinction) and determine masses and upper mass estimates for these 20 progenitor stars using the STARS stellar evolutionary code and a single consistent homogeneous method. A maximum likelihood calculation suggests that the minimum stellar mass for a Type II-P to form is m(min) = 8.5(-1.5)(+1) M-circle dot and the maximum mass for II-P progenitors is m(max) = 16.5 +/- 1.5 M-circle dot, assuming a Salpeter initial mass function holds for the progenitor population (in the range Gamma = -1.35(-0.7)(+0.3)). The minimum mass is consistent with current estimates for the upper limit to white dwarf progenitor masses, but the maximum mass does not appear consistent with massive star populations in Local Group galaxies. Red supergiants in the Local Group have masses up to 25 M-circle dot and the minimum mass to produce a Wolf-Rayet star in single star evolution (between solar and LMC metallicity) is similarly 25-30 M-circle dot. The reason we have not detected any high-mass red supergiant progenitors above 17 M-circle dot is unclear, but we estimate that it is statistically significant at 2.4 sigma confidence. Two simple reasons for this could be that we have systematically underestimated the progenitor masses due to dust extinction or that stars between 17-25 M-circle dot produce other kinds of SNe which are not II-P. We discuss these possibilities and find that neither provides a satisfactory solution. We term this discrepancy the 'red supergiant problem' and speculate that these stars could have core masses high enough to form black holes and SNe which are too faint to have been detected. We compare the Ni-56 masses ejected in the SNe to the progenitor mass estimates and find that low-luminosity SNe with low Ni-56 production are most likely to arise from explosions of low-mass progenitors near the mass threshold that can produce a core-collapse.

The HIPASS catalogue - I. Data presentation

The H I Parkes All-Sky Survey (HIPASS) catalogue forms the largest uniform catalogue of H I sources compiled to date, with 4315 sources identified purely by their H I content. The catalogue data comprise the southern region delta < + 2&DEG; of HIPASS, the first blind H I survey to cover the entire southern sky. The rms noise for this survey is 13 mJy beam(-1) and the velocity range is -1280 to 12 700 km s(-1). Data search, verification and parametrization methods are discussed along with a description of measured quantities. Full catalogue data are made available to the astronomical community including positions, velocities, velocity widths, integrated fluxes and peak flux densities. Also available are on-sky moment maps, position-velocity moment maps and spectra of catalogue sources. A number of local large-scale features are observed in the space distribution of sources, including the super-Galactic plane and the Local Void. Notably, large-scale structure is seen at low Galactic latitudes, a region normally obscured at optical wavelengths.

Visualization of predictive distributions for discrete spatial-temporal log Cox processes approximated with MCMC

An important aspect of decision support systems involves applying sophisticated and flexible statistical models to real datasets and communicating these results to decision makers in interpretable ways. An important class of problem is the modelling of incidence such as fire, disease etc. Models of incidence known as point processes or Cox processes are particularly challenging as they are ‘doubly stochastic’ i.e. obtaining the probability mass function of incidents requires two integrals to be evaluated. Existing approaches to the problem either use simple models that obtain predictions using plug-in point estimates and do not distinguish between Cox processes and density estimation but do use sophisticated 3D visualization for interpretation. Alternatively other work employs sophisticated non-parametric Bayesian Cox process models, but do not use visualization to render interpretable complex spatial temporal forecasts. The contribution here is to fill this gap by inferring predictive distributions of Gaussian-log Cox processes and rendering them using state of the art 3D visualization techniques. This requires performing inference on an approximation of the model on a discretized grid of large scale and adapting an existing spatial-diurnal kernel to the log Gaussian Cox process context.

Synthesis and application of weight function for edge cracked semicircular disk (ECSD)

We analyze the utility of edge cracked semicircular disk (ECSD) for rapid assessment of fracture toughness using compressive loading. Continuing our earlier work on ECSD, a theoretical examination here leads to a novel way for synthesizing weight functions using two distinct form factors. The efficacy of ECSD mode-I weight function synthesized using displacement and form factor methods is demonstrated by comparing with finite element results. Theory of elasticity in conjunction with finite element method is utilized to analyze crack opening potency of ECSD under eccentric compression to explore newer configurations of ECSD for fracture testing.

Chemically tagging the Hyades stream: does it partly originate from the Hyades cluster?

The Hyades stream has long been thought to be a dispersed vestige of the Hyades cluster. However, recent analyses of the parallax distribution, of the mass function, and of the action-space distribution of stream stars have shown it to be rather composed of orbits trapped at a resonance of a density disturbance. This resonant scenario should leave a clearly different signature in the element abundances of stream stars than the dispersed cluster scenario, since the Hyades cluster is chemically homogeneous. Here, we study the metallicity as well as the element abundances of Li, Na, Mg, Fe, Zr, Ba, La, Ce, Nd and Eu for a random sample of stars belonging to the Hyades stream, and compare them with those of stars from the Hyades cluster. From this analysis: (i) we independently confirm that the Hyades stream cannot be solely composed of stars originating in the Hyades cluster; (ii) we show thatsomestars (namely 2/21) from the Hyades stream nevertheless have abundances compatible with an origin in the cluster; (iii) we emphasize that the use of Li as a chemical tag of the cluster origin of main-sequence stars is very efficient in the range 5500K ≤Teff≤ 6200K, since the Li sequence in the Hyades cluster is very tight, while at the same time spanning a large abundance range; (iv) we show that, while this evaporated population has a metallicity excess of ~0.2 dex with respect to the local thin-disc population, identical to that of the Hyades cluster, the remainder of the Hyades stream population has still a metallicity excess of ~0.06-0.15 dex, consistent with an origin in the inner Galaxy and (v) we show that the Hyades stream can be interpreted as an inner 4:1 resonance of the spiral pattern: this then also reproduces an orbital family compatible with the Sirius stream, and places the origin of the Hyades stream up to 1kpc inwards from the solar radius, which might explain the observed metallicity excess of the stream population. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

Observational Constraints on the Progenitors of Core-Collapse Supernovae: The Case for Missing High-Mass Stars

Over the last 15 years, the supernova community has endeavoured to directly identify progenitor stars for core-collapse supernovae discovered in nearby galaxies. These precursors are often visible as resolved stars in high-resolution images from space-and ground-based telescopes. The discovery rate of progenitor stars is limited by the local supernova rate and the availability and depth of archive images of galaxies, with 18 detections of precursor objects and 27 upper limits. This review compiles these results (from 1999 to 2013) in a distance-limited sample and discusses the implications of the findings. The vast majority of the detections of progenitor stars are of type II-P, II-L, or IIb with one type Ib progenitor system detected and many more upper limits for progenitors of Ibc supernovae (14 in all). The data for these 45 supernovae progenitors illustrate a remarkable deficit of high-luminosity stars above an apparent limit of log L/L-circle dot similar or equal to 5.1 dex. For a typical Salpeter initial mass function, one would expect to have found 13 high-luminosity and high-mass progenitors by now. There is, possibly, only one object in this time-and volume-limited sample that is unambiguously high-mass (the progenitor of SN2009ip) although the nature of that supernovae is still debated. The possible biases due to the influence of circumstellar dust, the luminosity analysis, and sample selection methods are reviewed. It does not appear likely that these can explain the missing high-mass progenitor stars. This review concludes that the community's work to date shows that the observed populations of supernovae in the local Universe are not, on the whole, produced by high-mass (M greater than or similar to 18 M-circle dot) stars. Theoretical explosions of model stars also predict that black hole formation and failed supernovae tend to occur above an initial mass of M similar or equal to 18 M-circle dot. The models also suggest there is no simple single mass division for neutron star or black-hole formation and that there are islands of explodability for stars in the 8-120 M-circle dot range. The observational constraints are quite consistent with the bulk of stars above M similar or equal to 18 M-circle dot collapsing to form black holes with no visible supernovae.

Identification des peptides du complexe majeur d’histocompatibilité de classe I par spectrométrie de masse

L’immunité adaptive et la discrimination entre le soi et le non-soi chez les vertébrés à mâchoire reposent sur la présentation de peptides par les récepteurs d’histocompatibilité majeur de classe I. Les peptides antigéniques, présentés par les molécules du complexe d’histocompatibilité (CMH), sont scrutés par les lymphocytes T CD8 pour une réponse immunitaire appropriée. Le répertoire des peptides du CMH de classe I, aussi appelé immunopeptidome, est généré par la dégradation protéosomale des protéines endogènes, et a un rôle essentiel dans la régulation de l’immunité cellulaire. La composition de l’immunopeptidome dépend du type de cellule et peut présenter des caractéristiques liées à des maladies comme le cancer. Les peptides antigéniques peuvent être utilisés à des fins immunothérapeutiques notamment dans le traitement voire la prévention de certains cancers. La spectrométrie de masse est un outil de choix pour l’identification, le séquençage et la caractérisation de ces peptides. Cependant, la composition en acides aminés, la faible abondance et la diversité de ces peptides compliquent leur détection et leur séquençage. Nous avons développé un programme appelé StatPeaks qui permet de calculer un certains nombres de statistiques relatives à la fragmentation des peptides. À l’aide de ce programme, nous montrons sans équivoque que les peptides du CMH classe I, en mode de fragmentation par dissociation induite par collision (CID), fragmentent très différemment des peptides trypsiques communément utilisés en protéomique. Néanmoins, la fragmentation par décomposition induite par collision à plus haute énergie (HCD) proposée par le spectromètre LTQ-Orbitrap Velos améliore la fragmentation et fournit une haute résolution qui permet d’obtenir une meilleure confiance dans l’identification des peptides du CMH de classe I. Cet avantage permet d’effectuer le séquençage de novo pour identifier les variants polymorphes qui ne sont normalement pas identifiés par les recherches utilisant des bases de données. La comparaison des programmes de séquençage Lutefisk, pepNovo, pNovo, Vonode et Peaks met en évidence que le dernier permet d’identifier un plus grand nombre de peptides du CMH de classe I. Ce programme est intégré dans une chaîne de traitement de recherche d’antigènes mineurs d’histocompatibilité. Enfin, une base de données contenant les informations spectrales de plusieurs centaines de peptides du CMH de classe I accessible par Internet a été développée.

La recherche de naines brunes et étoiles de faible masse dans les associations cinématiques jeunes du voisinage solaire

L’objectif principal de cette thèse est d’identifier les étoiles de faible masse et naines brunes membres d’associations cinématiques jeunes du voisinage solaire. Ces associations sont typiquement âgées de moins de 200 millions d’années et regroupent chacune un ensemble d’étoiles s’étant formées au même moment et dans un même environnement. La majorité de leurs membres d'environ plus de 0.3 fois la masse du Soleil sont déjà connus, cependant les membres moins massifs (et moins brillants) nous échappent encore. Leur identification permettra de lever le voile sur plusieurs questions fondamentales en astrophysique. En particulier, le fait de cibler des objets jeunes, encore chauds et lumineux par leur formation récente, permettra d’atteindre un régime de masses encore peu exploré, jusqu'à seulement quelques fois la masse de Jupiter. Elles nous permettront entre autres de contraindre la fonction de masse initiale et d'explorer la connection entre naines brunes et exoplanètes, étant donné que les moins massives des naines brunes jeunes auront des propriétés physiques très semblables aux exoplanètes géantes gazeuses. Pour mener à bien ce projet, nous avons adapté l'outil statistique BANYAN I pour qu'il soit applicable aux objets de très faibles masses en plus de lui apporter plusieurs améliorations. Nous avons entre autres inclus l'utilisation de deux diagrammes couleur-magnitude permettant de différencier les étoiles de faible masse et naines brunes jeunes à celles plus vieilles, ajouté l'utilisation de probabilités a priori pour rendre les résultats plus réalistes, adapté les modèles spatiaux et cinématiques des associations jeunes en utilisant des ellipsoïdes gaussiennes tridimensionnelles dont l'alignement des axes est libre, effectué une analyse Monte Carlo pour caractériser le taux de faux-positifs et faux-négatifs, puis revu la structure du code informatique pour le rendre plus efficace. Dans un premier temps, nous avons utilisé ce nouvel algorithme, BANYAN II, pour identifier 25 nouvelles candidates membres d'associations jeunes parmi un échantillon de 158 étoiles de faible masse (de types spectraux > M4) et naines brunes jeunes déjà connues. Nous avons ensuite effectué la corrélation croisée de deux catalogues couvrant tout le ciel en lumière proche-infrarouge et contenant ~ 500 millions d’objets célestes pour identifier environ 100 000 candidates naines brunes et étoiles de faible masse du voisinage solaire. À l'aide de l'outil BANYAN II, nous avons alors identifié quelques centaines d'objets appartenant fort probablement à une association jeune parmi cet échantillon et effectué un suivi spectroscopique en lumière proche-infrarouge pour les caractériser. Les travaux présentés ici ont mené à l'identification de 79 candidates naines brunes jeunes ainsi que 150 candidates étoiles de faible masse jeunes, puis un suivi spectroscopique nous a permis de confirmer le jeune âge de 49 de ces naines brunes et 62 de ces étoiles de faible masse. Nous avons ainsi approximativement doublé le nombre de naines brunes jeunes connues, ce qui a ouvert la porte à une caractérisation statistique de leur population. Ces nouvelles naines brunes jeunes représentent un laboratoire idéal pour mieux comprendre l'atmosphère des exoplanètes géantes gazeuses. Nous avons identifié les premiers signes d’une remontée dans la fonction de masse initiale des naines brunes aux très faibles masses dans l'association jeune Tucana-Horologium, ce qui pourrait indiquer que l’éjection d’exoplanètes joue un rôle important dans la composition de leur population. Les résultats du suivi spectroscopique nous ont permis de construire une séquence empirique complète pour les types spectraux M5-L5 à l'âge du champ, à faible (β) et très faible (γ) gravité de surface. Nous avons effectué une comparaison de ces données aux modèles d'évolution et d'atmosphère, puis nous avons construit un ensemble de séquences empiriques de couleur-magnitude et types spectraux-magnitude pour les naines brunes jeunes. Finalement, nous avons découvert deux nouvelles exoplanètes par un suivi en imagerie directe des étoiles jeunes de faible masse identifiées dans ce projet. La future mission GAIA et le suivi spectroscopique complet des candidates présentées dans cette thèse permettront de confirmer leur appartenance aux associations jeunes et de contraindre la fonction de masse initiale dans le régime sous-stellaire.