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1.
Spectroscopic analysis of the strongly lensed SN Encore : constraints on cosmic evolution of Type Ia supernovae
S. Dhawan, Justin Pierel, M. Gu, A. B. Newman, C. Larison, M. Siebert, Tanja Petrushevska, F. Poidevin, S. W. Jha, W. Chen, 2024, izvirni znanstveni članek

Opis: Abstract Strong gravitational lensing magnifies the light from a background source, allowing us to study these sources in detail. Here, we study the spectra of a z = 1.95 lensed Type Ia supernova SN Encore for its brightest Image A, taken 39 days apart. We infer the spectral age with template matching using the supernova identification (SNID) software and find the spectra to be at 29.0 ±5.0 and 37.4 ±2.8 rest-frame days post maximum respectively, consistent with separation in the observer frame after accounting for time-dilation. Since SNe Ia measure dark energy properties by providing relative distances between low- and high-z SNe, it is important to test for evolution of spectroscopic properties. Comparing the spectra to composite low-z SN Ia spectra, we find strong evidence for similarity between the local sample and SN Encore. The line velocities of common SN Ia spectral lines, Si II 6355 and Ca II NIR triplet are consistent with the distribution for the low-z sample as well as other lensed SNe Ia, e.g. iPTF16geu (z = 0.409)and SN H0pe (z = 1.78). The consistency between the low-z sample and lensed SNe at high-z suggests no obvious cosmic evolution demonstrating their using as high-z distance indicators, though this needs to be confirmed/refuted via a larger sample. We also find that the spectra of SN Encore match the predictions for explosion models very well. With future large samples of lensed SNe Ia e.g. with the Vera C. Rubin Observatory, spectra at such late phases will be important to distinguish between different explosion scenarios.
Ključne besede: Encore
Objavljeno v RUNG: 29.10.2024; Ogledov: 371; Prenosov: 1
.pdf Celotno besedilo (6,45 MB)
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Cluster-lensed supernovae with the Roman Space Telescope and Vera Rubin observatory
Mateusz Bronikowski, Tanja Petrushevska, Justin Pierel, 2022, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: I will present our current efforts to enable the use of strongly lensed supernovae behind galaxy clusters as powerful tools to tackle several open questions in astrophysics and cosmology. As a preparatory task, we are collecting all available gravitational telescopes into a database, and estimating the properties of all reported multiply-imaged galaxies behind clusters. We are building a tool that will enable accurate estimates of cluster-lensed supernova yields for a given survey. In addition, we are developing the methods to extract the cosmological parameters from cluster-lensed supernovae in the Rubin and Roman data.
Ključne besede: supernova, gravitational lensing, Vera Rubin Observatory, Roman Space telescope, LSST, Hubble constant
Objavljeno v RUNG: 09.11.2022; Ogledov: 1955; Prenosov: 8
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Atmospheric chemistry and physics in the atmosphere of a developed megacity (London): An overview of the REPARTEE experiment and its conclusions
Roy M Harrison, Manuel DallOsto, David C S Beddows, Alistair J Thorpe, William J Bloss, James D Allan, Hugh Coe, James R Dorsey, Martin W Gallagher, Claire Martin, John Whitehead, Paul I Williams, Roderick L Jones, Justin M Langridge, A K Benton, Stephen M Ball, Ben Langford, C Nicholas Hewitt, Brian Davison, Damien Martin, K Fredrik Peterson, Stephen J Henshaw, Iain R. White, Dudley E Shallcross, Janet F Barlow, Tyrone Dunbar, Fay Davies, Eiko Nemitz, Gavin J Phillips, Carole Helfter, Chiara F Di Marco, Steven Smith, 2012, pregledni znanstveni članek

Opis: The Regents Park and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London in October 2006 and October/November 2007. The experiment design involved measurements at a heavily trafficked roadside site, two urban background sites and an elevated site at 160-190 m above ground on the BT Tower, supplemented in the second campaign by Doppler lidar measurements of atmospheric vertical structure. A wide range of measurements of airborne particle physical metrics and chemical composition were made as well as measurements of a considerable range of gas phase species and the fluxes of both particulate and gas phase substances. Significant findings include (a) demonstration of the evaporation of traffic-generated nanoparticles during both horizontal and vertical atmospheric transport; (b) generation of a large base of information on the fluxes of nanoparticles, accumulation mode particles and specific chemical components of the aerosol and a range of gas phase species, as well as the elucidation of key processes and comparison with emissions inventories; (c) quantification of vertical gradients in selected aerosol and trace gas species which has demonstrated the important role of regional transport in influencing concentrations of sulphate, nitrate and secondary organic compounds within the atmosphere of London; (d) generation of new data on the atmospheric structure and turbulence above London, including the estimation of mixed layer depths; (e) provision of new data on trace gas dispersion in the urban atmosphere through the release of purposeful tracers; (f) the determination of spatial differences in aerosol particle size distributions and their interpretation in terms of sources and physico-chemical transformations; (g) studies of the nocturnal oxidation of nitrogen oxides and of the diurnal behaviour of nitrate aerosol in the urban atmosphere, and (h) new information on the chemical composition and source apportionment of particulate matter size fractions in the atmosphere of London derived both from bulk chemical analysis and aerosol mass spectrometry with two instrument types.
Ključne besede: megacity, trace gas, urban atmosphere, atmospheric transport, chemical composition, aerosol
Objavljeno v RUNG: 18.07.2019; Ogledov: 4144; Prenosov: 0
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Dispersion experiments in central London: The 2007 DAPPLE project
Curtis R Wood, Samantha J Arnold, Ahmed A Balogun, Janet F Barlow, Stephen E Belcher, Rex E Britter, Hong Cheng, Adrian Dobre, Justin J N Lingard, Damien Martin, Marina K Neophytou, Fredrik K Petersson, Alan G Robins, Dudley E. Shallcross, Robert J Smalley, James E Tate, Alison S Tomlin, Iain R. White, 2009, izvirni znanstveni članek

Opis: In the event of a release of toxic gas in the center of London, emergency services personnel would need to determine quickly the extent of the area contaminated. The transport of pollutants by turbulent flow within the complex streets and building architecture of London, United Kingdom, is not straightforward, and we might wonder whether it is at all possible to make a scientifically reasoned decision. Here, we describe recent progress from a major U.K. project, Dispersion of Air Pollution and its Penetration into the Local Environment (DAPPLE; information online at www.dapple.org.uk). In DAPPLE, we focus on the movement of airborne pollutants in cities by developing a greater understanding of atmospheric flow and dispersion within urban street networks. In particular, we carried out full-scale dispersion experiments in central London from 2003 through 2008 to address the extent of the dispersion of tracers following their release at street level. These measurements complemented previous studies because 1) our focus was on dispersion within the first kilometer from the source, when most of the material was expected to remain within the street network rather than being mixed into the boundary layer aloft; 2) measurements were made under a wide variety of meteorological conditions; and 3) central London represents a European, rather than North American, city geometry. Interpretation of the results from the full-scale experiments was supported by extensive numerical and wind tunnel modeling, which allowed more detailed analysis under idealized and controlled conditions. In this article, we review the full-scale DAPPLE methodologies and show early results from the analysis of the 2007 field campaign data.
Ključne besede: Air quality, Atmospheric thermodynamics, Dispersions, Experiments
Objavljeno v RUNG: 18.07.2019; Ogledov: 4839; Prenosov: 0
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ESTIMATING THE GeV EMISSION OF MILLISECOND PULSARS IN DWARF SPHEROIDAL GALAXIES
Miles Winter, Gabrijela Zaharijas, Keith Bechtol, Justin Vandenbroucke, 2016, izvirni znanstveni članek

Ključne besede: dark matter – Local Group – pulsars: general
Objavljeno v RUNG: 28.11.2016; Ogledov: 5383; Prenosov: 0
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Changes in the relative abundance of two Saccharomyces species from oak forests to wine fermentations
Sofia Dashko, Ping Liu, Helena Volk, Lorena Butinar, Jure Piškur, Justin C. Fay, 2016, izvirni znanstveni članek

Opis: Saccharomyces cerevisiae and its sibling species S. paradoxus are known to inhabit temperate arboreal habitats across the globe. Despite their sympatric distribution in the wild, S. cerevisiae is predominantly associated with human fermentations. The apparent ecological differentiation of these species is particularly striking in Europe where S. paradoxus is abundant in forests and S. cerevisiae is abundant in vineyards. However, ecological differences may be confounded with geographic differences in species abundance. To compare the distribution and abundance of these two species we isolated Saccharomyces strains from over 1,200 samples taken from vineyard and forest habitats in Slovenia. We isolated numerous strains of S. cerevisiae and S. paradoxus as well as small number of S. kudriavzevii strains from both vineyard and forest environments. We find S. cerevisiae less abundant than S. paradoxus on oak trees both within and outside the vineyard, but more abundant on grapevines and associated substrates. Analysis of the uncultured microbiome shows that both S. cerevisiae and S. paradoxus are rare species in soil and bark samples, but can be much more common in grape must. In contrast to S. paradoxus, European strains of S. cerevisiae have acquired multiple traits thought to be important for life in the vineyard and dominance of wine fermentations. We conclude that S. cerevisiae and S. paradoxus currently share both vineyard and non-vineyard habitats in Slovenia and we discuss factors relevant to their global distribution and relative abundance.
Ključne besede: Wine, microbiome, yeast, Ecology, Fermentation
Objavljeno v RUNG: 12.02.2016; Ogledov: 6681; Prenosov: 203
.pdf Celotno besedilo (3,21 MB)

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