Towards a concordant model of halo occupation statistics

We use the conditional luminosity function (CLF) and data from the 2-degree Field Galaxy Redshift Survey (2dFGRS) to constrain the average relation between light and mass in a Lambda cold dark matter (ΛCDM) cosmology with Ωm= 0.23 and σ8= 0.74 (hereafter WMAP3 cosmology). Reproducing the observed luminosity dependence of the galaxy two-point correlation function results in average mass-to-light ratios that are ∼35 per cent lower than those in a ΛCDM cosmology with Ωm= 0.3 and σ8= 0.9 (hereafter WMAP1 cosmology). This removes an important problem with previous halo occupation models which had a tendency to predict cluster mass-to-light ratios that were too high. For the WMAP3 cosmology, our model yields average mass-to-light ratios, central galaxy luminosities, halo occupation numbers, satellite fractions and luminosity-gap statistics, that are all in excellent agreement with those obtained from a 2dFGRS group catalogue and from other independent studies. We also use our CLF model to compute the probability distribution P(M | Lcen), that a central galaxy of luminosity Lcen resides in a halo of mass M. We find this distribution to be much broader than what is typically assumed in halo occupation distribution models, which has important implications for the interpretation of satellite kinematics and galaxy-galaxy lensing data. Finally, reproducing the luminosity dependence of the pairwise peculiar velocity dispersions in the 2dFGRS requires relatively low mass-to-light ratios for clusters and a satellite fraction that decreases strongly with increasing luminosity. This is only marginally consistent with the constraints obtained from the luminosity dependence of the galaxy two-point correlation function. We argue that a cosmology with parameters between those of the WMAP1 and WMAP3 cosmologies is likely to yield results with a higher level of consistenc

Towards a Concordant Model of Halo Occupation Statistics

We use the conditional luminosity function (CLF) and data from the 2dFGRS to constrain the average relation between light and mass in a LCDM cosmology with Omega_m=0.23 and sigma_8=0.74 (hereafter WMAP3 cosmology). Reproducing the observed luminosity dependence of the galaxy two-point correlation function results in average mass-to-light ratios that are about 35 percent lower than in a LCDM cosmology with Omega_m=0.3 and sigma_8=0.9 (hereafter WMAP1 cosmology). This removes an important problem with previous halo occupation models which had a tendency to predict cluster mass-to-light ratios that were too high. For the WMAP3 cosmology our model yields average mass-to-light ratios, central galaxy luminosities, halo occupation numbers, satellite fractions, and luminosity-gap statistics, that are all in excellent agreement with those obtained from a 2dFGRS group catalogue and from other independent studies. We also use our CLF model to compute the probability distribution P(M|L_cen), that a central galaxy of luminosity L_cen resides in a halo of mass M. We find this distribution to be much broader than what is typically assumed in HOD models, which has important implications for the interpretation of galaxy-galaxy lensing data. Finally, reproducing the luminosity dependence of the pairwise velocity dispersions in the 2dFGRS requires relatively low mass-to-light ratios for clusters and a satellite fraction that decreases strongly with increasing luminosity. This is only marginally consistent with our CLF constraints. We argue that a cosmology with parameters between those of the WMAP1 and WMAP3 cosmologies is likely to yield results with a higher level of consistency.Comment: 23 pages, 11 figures. Submitted for publication in MNRA

Elliptical Galaxies and Bulges of Disk Galaxies: Summary of Progress and Outstanding Issues

This is the summary chapter of a review book on galaxy bulges. Bulge properties and formation histories are more varied than those of ellipticals. I emphasize two advances: 1 - "Classical bulges" are observationally indistinguishable from ellipticals, and like them, are thought to form by major galaxy mergers. "Disky pseudobulges" are diskier and more actively star-forming (except in S0s) than are ellipticals. Theys are products of the slow ("secular") evolution of galaxy disks: bars and other nonaxisymmetries move disk gas toward the center, where it starbursts and builds relatively flat, rapidly rotating components. This secular evolution is a new area of galaxy evolution work that complements hierarchical clustering. 2 - Disks of high-redshift galaxies are unstable to the formation of mass clumps that sink to the center and merge - an alternative channel for the formation of classical bulges. I review successes and unsolved problems in the formation of bulges+ellipticals and their coevolution (or not) with supermassive black holes. I present an observer's perspective on simulations of dark matter galaxy formation including baryons. I review how our picture of the quenching of star formation is becoming general and secure at redshifts z < 1. The biggest challenge is to produce realistic bulges+ellipticals and disks that overlap over a factor of 10**3 in mass but that differ from each other as observed over that whole range. Second, how does hierarchical clustering make so many giant, bulgeless galaxies in field but not cluster environments? I argue that we rely too much on AGN and star-formation feedback to solve these challenges.Comment: 46 pages, 10 postscript figures, accepted for publication in Galactic Bulges, ed. E. Laurikainen, R. F. Peletier, & D. A. Gadotti (New York: Springer), in press (2015

Material deprivation affects the management and clinical outcome of hepatocellular carcinoma in a high-resource environment

none94Aim: This study investigated how material deprivation in Italy influences the stage of hepatocellular carcinoma (HCC) at diagnosis and the chance of cure. Methods: 4114 patients from the Italian Liver Cancer database consecutively diagnosed with HCC between January 2008 and December 2018 were analysed about severe material deprivation (SMD) rate tertiles of the region of birth and region of managing hospitals, according to the European Statistics on Income and Living Conditions. The main outcomes were HCC diagnosis modalities (during or outside surveillance), treatment adoption and overall survival. Results: In more deprived regions, HCC was more frequently diagnosed during surveillance, while the incidental diagnosis was prevalent in the least deprived. Tumour characteristics did not differ among regions. The proportion of patients undergoing potentially curative treatments progressively decreased as the SMD worsened. Consequently, overall survival was better in less deprived regions. Patients who moved from most deprived to less deprived regions increased their probability of receiving potentially curative treatments by 1.11 times (95% CI 1.03 to 1.19), decreasing their mortality likelihood (hazard ratio 0.78 95% CI 0.67 to 0.90). Conclusions: Socioeconomic status measured through SMD does not seem to influence HCC features at diagnosis but brings a negative effect on the chance of receiving potentially curative treatments. Patient mobility from the most deprived to the less deprived regions increased the access to curative therapies, with the ultimate result of improving survival.openCucchetti A.; Gramenzi A.; Johnson P.; Giannini E.G.; Tovoli F.; Rapaccini G.L.; Marra F.; Cabibbo G.; Caturelli E.; Gasbarrini A.; Svegliati-Baroni G.; Sacco R.; Zoli M.; Morisco F.; Di Marco M.; Mega A.; Foschi F.G.; Biasini E.; Masotto A.; Nardone G.; Raimondo G.; Azzaroli F.; Vidili G.; Brunetto M.R.; Farinati F.; Trevisani F.; Avanzato F.; Biselli M.; Caraceni P.; Garuti F.; Neri A.; Santi V.; Pellizzaro F.; Imondi A.; Sartori A.; Penzo B.; Sanmarco A.; Granito A.; Muratori L.; Piscaglia F.; Sansone V.; Forgione A.; Dajti E.; Marasco G.; Ravaioli F.; Cappelli A.; Golfieri R.; Mosconi C.; Renzulli M.; Cela E.M.; Facciorusso A.; Cacciato V.; Casagrande E.; Moscatelli A.; Pellegatta G.; de Matthaeis N.; Allegrini G.; Lauria V.; Ghittoni G.; Pelecca G.; Chegai F.; Coratella F.; Ortenzi M.; Missale G.; Olivani A.; Inno A.; Marchetti F.; Busacca A.; Camma C.; Di Martino V.; Maria Rizzo G.E.; Franze M.S.; Saitta C.; Sauchella A.; Berardinelli D.; Bevilacqua V.; Borghi A.; Gardini A.C.; Conti F.; Dall'Aglio A.C.; Ercolani G.; Adotti V.; Arena U.; Di Bonaventura C.; Campani C.; Dragoni G.; Gitto S.; Laffi G.; Coccoli P.; Malerba A.; Guarino M.; Capasso M.; Oliveri F.; Romagnoli V.Cucchetti, A.; Gramenzi, A.; Johnson, P.; Giannini, E. G.; Tovoli, F.; Rapaccini, G. L.; Marra, F.; Cabibbo, G.; Caturelli, E.; Gasbarrini, A.; Svegliati-Baroni, G.; Sacco, R.; Zoli, M.; Morisco, F.; Di Marco, M.; Mega, A.; Foschi, F. G.; Biasini, E.; Masotto, A.; Nardone, G.; Raimondo, G.; Azzaroli, F.; Vidili, G.; Brunetto, M. R.; Farinati, F.; Trevisani, F.; Avanzato, F.; Biselli, M.; Caraceni, P.; Garuti, F.; Neri, A.; Santi, V.; Pellizzaro, F.; Imondi, A.; Sartori, A.; Penzo, B.; Sanmarco, A.; Granito, A.; Muratori, L.; Piscaglia, F.; Sansone, V.; Forgione, A.; Dajti, E.; Marasco, G.; Ravaioli, F.; Cappelli, A.; Golfieri, R.; Mosconi, C.; Renzulli, M.; Cela, E. M.; Facciorusso, A.; Cacciato, V.; Casagrande, E.; Moscatelli, A.; Pellegatta, G.; de Matthaeis, N.; Allegrini, G.; Lauria, V.; Ghittoni, G.; Pelecca, G.; Chegai, F.; Coratella, F.; Ortenzi, M.; Missale, G.; Olivani, A.; Inno, A.; Marchetti, F.; Busacca, A.; Camma, C.; Di Martino, V.; Maria Rizzo, G. E.; Franze, M. S.; Saitta, C.; Sauchella, A.; Berardinelli, D.; Bevilacqua, V.; Borghi, A.; Gardini, A. C.; Conti, F.; Dall'Aglio, A. C.; Ercolani, G.; Adotti, V.; Arena, U.; Di Bonaventura, C.; Campani, C.; Dragoni, G.; Gitto, S.; Laffi, G.; Coccoli, P.; Malerba, A.; Guarino, M.; Capasso, M.; Oliveri, F.; Romagnoli, V

Floristic analysis of a high-speed railway embankment in a Mediterranean landscape

We analyzed the floristic composition of a 4.5 km-long segment of a high-speed railway in Lazio, central Italy, which travels on an artificial embankment through an intensively-farmed landscape. In total, 287 vascular plant species were recorded. The life-form distribution was found to be similar to that of the regional species pool, with high percentages of therophytes (38%) and phanerophytes (13%). In the chorological spectrum the Mediterranean floristic element prevailed (44%), while alien species were 8% of the flora. The phytosociological spectrum showed a high diversity of characteristic species from the class Stellarietea mediae or its subordinate syntaxa (26%), and in particular from the order Thero-Brometalia (Mediterranean, sub-nitrophilous annual communities). Species from forest syntaxa had a relatively high diversity (9%). These results suggest that the ecological filtering provided by the Mediterranean regional climate controlled species assemblage even in a completely artificial habitat, preventing floristic homogenization: the flora of the studied railway section is only partially »ruderalized«, while it keeps strong links with the regional (semi-) natural plant communities. However, in contrast to what is observed in central and north Europe, the railway sides studied in the present paper do not seem to represent a refugial habitat for rare species from grassland communities, mainly because in Italy semi-natural dry grasslands are still widely represented

Globular cluster systems and galaxy formation

Globular clusters are compact, gravitationally bound systems of up to a million stars. The GCs in the Milky Way contain some of the oldest stars known, and provide important clues to the early formation and continuing evolution of our Galaxy. More generally, GCs are associated with galaxies of all types and masses, from low-mass dwarf galaxies to the most massive early-type galaxies which lie in the centres of massive galaxy clusters. GC systems show several properties which connect tightly with properties of their host galaxies. For example, the total mass of GCs in a system scales linearly with the dark matter halo mass of its host galaxy. Numerical simulations are at the point of being able to resolve globular cluster formation within a cosmological framework. Therefore, GCs link a range of scales, from the physics of star formation in turbulent gas clouds, to the large-scale properties of galaxies and their dark matter. In this Chapter we review some of the basic observational approaches for GC systems, some of their key observational properties, and describe how GCs provide important clues to the formation of their parent galaxies.Comment: 32 pages, 6 figures. Accepted for publication in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556

Ag/TiO2 nanocomposite for visible light-driven photocatalysis

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Plasmon-resonant Raman spectroscopy in metallic nanoparticles: Surface-enhanced scattering by electronic excitations

cited By 7International audienceSince the discovery of surface-enhanced Raman scattering (SERS) 40 years ago, the origin of the "background" that is systematically observed in SERS spectra has remained questionable. To deeply analyze this phenomenon, plasmon-resonant Raman scattering was recorded under specific experimental conditions on a panel of composite multilayer samples containing noble metal (Ag and Au) nanoparticles. Stokes, anti-Stokes, and wide, including very low, frequency ranges have been explored. The effects of temperature, size (in the nm range), embedding medium (SiO2, Si3N4, or TiO2) or ligands have been successively analyzed. Both lattice (Lamb modes and bulk phonons) and electron (plasmon mode and electron-hole excitations) dynamics have been investigated. This work confirms that in Ag-based nanoplasmonics composite layers, only Raman scattering by single-particle electronic excitations accounts for the background. This latter appears as an intrinsic phenomenon independently of the presence of molecules on the metallic surface. Its spectral shape is well described by revisiting a model developed in the 1990s for analyzing electron scattering in dirty metals, and used later in superconductors. The gs factor, that determines the effective mean-free path of free carriers, is evaluated, gsexpt=0.33±0.04, in good agreement with a recent evaluation based on time-dependent local density approximation gstheor=0.32. Confinement and interface roughness effects at the nanometer range thus appear crucial to understand and control SERS enhancement and more generally plasmon-enhanced processes on metallic surfaces

Black TiOx photocatalyst obtained by laser irradiation in water

cited By 10International audienceIn this work, we present the synthesis of a nanostructured TiOx film on a Ti foil by using a scalable and environmental friendly methodology such as the laser irradiation in liquid. The obtained black-TiOx film is composed by amorphous titanates and shows a high absorption in both visible and UV range. The introduction of a thin layer of Pt nanoparticles (PtNps) on the rear side of the Ti foil, gave rise to a stacked layered structure (TiOx/Ti/PtNps) that boosted the quantum photocatalytical efficiency, according to ISO 10678:2010. Such enhancement is discussed in terms of hole trapping by surface states and electron scavenging by the Pt Nps