327 research outputs found

    Scaling relations of the colour-detected cluster RzCS 052 at z=1.016 and of some other high redshift clusters

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    We report on the discovery of the z=1.016 cluster RzCS 052 using a modified red sequence method, followup spectroscopy and X-ray imaging. This cluster has a velocity dispersion of 710+-150 km/s, a virial mass of 4.0e14 Msol (based on 21 spectroscopically confirmed members) and an X-ray luminosity of (0.68+- 0.47)e44 ergs/s in the [1-4] keV band. This optically selected cluster appears to be of richness class 3 and to follow the known L_X-sigma_v relation for high redshift X-ray selected clusters. Using these data, we find that the halo occupation number for this cluster is only marginally consistent with what expected assuming a self-similar evolution of cluster scaling relations, suggesting perhaps a break of them at z~1. We also rule out a strong galaxy merging activity between z=1 and today. Finally, we present a Bayesian approach to measuring cluster velocity dispersions and X-ray luminosities in the presence of a background: we critically reanalyze recent claims for X-ray underluminous clusters using these techniques and find that the clusters can be accommodated within the existing L_X -sigma_v relation.Comment: MNRAS, in pres

    Manufacturing reshoring and its limits:the UK automotive case

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    This paper explores the meaning of reshoring and its drivers in the case of UK manufacturing and in particular its automotive sector. Drawing on interviews, policy reviews and a range of recent surveys, the paper finds that while reshoring is a discernable trend in UK manufacturing, it is less pronounced than many have claimed and that – in the UK case at least - there are severe limits as to how far this reshoring trend can go, particularly in relation to the availability of skills and finance in the supply chain. This is in turn raises questions over the stance of British policy and whether more could be done, with comparisons made to US experience

    Galaxy Orientations in the Coma Cluster

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    We have examined the orientations of early-type galaxies in the Coma cluster to see whether the well-established tendency for brightest cluster galaxies to share the same major axis orientation as their host cluster also extends to the rest of the galaxy population. We find no evidence of any preferential orientations of galaxies within Coma or its surroundings. The implications of this result for theories of the formation of clusters and galaxies (particularly the first-ranked members) are discussed.Comment: Accepted for publication in the Astrophysical Journal Letters. 4 pages, 4 figure

    Anthropic pressures on Nature 2000 Sites: recommendations and monitoring criteria for the pollution emergency response activities within the Orbetello lagoon

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    L’elevato valore naturalistico e socioeconomico di un Sito Natura 2000 richiede che tutte le attività antropiche che si svolgono al suo interno (es. pesca, turismo, trasporti, attività industriali, etc.) siano gestite in maniera tale da non pregiudicare le specie e gli habitat per i quali l’area è stata designata. Molti di questi Siti sono ambienti di transizione, ovvero zone che costituiscono il passaggio naturale tra terra e mare. La loro posizione di interfaccia tra questi due ambienti li rende ecosistemi unici e biologicamente molto produttivi, sede di meccanismi di regolazione dei processi interattivi della biosfera nelle due fasi, terrestre e marina. In alcuni Siti la presenza di attività antropiche diffuse e prolungate nel tempo ha portato al riscontro di stati di contaminazione elevata, fino all’inclusione di queste zone, o parti di esse, tra i Siti di bonifica di Interesse Nazionale (SIN). Il presente lavoro descrive le linee di indirizzo e le attività di monitoraggio da attuare per la salvaguardia della salute pubblica e dell’ambiente nel corso degli interventi di messa in sicurezza di emergenza predisposti nell’area lagunare antistante l’area industriale Ex Sitoco, all’interno della perimetrazione del SIN di Orbetello, incluso in un Sito di Importanza Comunitaria. Le matrici ambientali potenzialmente a rischio a causa dell’esecuzione di tali interventi sono: acqua, sedimento, biocenosi acquatiche, avifauna, uomo. È altresì importante valutare gli effetti che le ipotetiche modifiche su microscala, apportate a livello di ogni matrice, potrebbero causare nel lungo periodo su macroscala.The high naturalistic and socio-economic value of Natura 2000 sites requires that all human activities performed within their borders (e.g. fishing, tourism, transports, industrial activities) are regulated. Indeed, the site management should assure the effective safeguard of all species and habitats of European interest included in the protected area. A lot of such sites are located in transitional environments, that are areas characterised by a natural progression from the terrestrial to the water environments. Such environments include unique and very productive habitats, and they represent the regulation mechanisms of the interactive processes of the terrestrial and marine biosphere. In some sites, the presence of human activities that are distributed both in space and time has led to high levels of contamination, that in some cases even required their inclusion in Reclamation Sites of National Interest (SIN). The present study describes the planning and monitoring activities to be performed in order to safeguard human and environment health during the actions of MISE in the lagoonal area in front of the industrial area Ex Sitoco, within the borders of the Orbetello SIN, included in a SCI. The environmental parameters that are potentially at risk due to such activities are: water, sediment, water biocenosis, birds, humans. Furthermore, it is important to evaluate the effects that potential variations at the microscale level may cause at the macroscale level

    Local industrial systems and the location of FDI in Italy

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    This article investigates the determinants of foreign direct investment (FDI)location across Italian provinces. Specifically it examines the relationship between industry- specific local industrial systems and the location of inward FDI. This extends previous analysis beyond the mere density of activity, to illustrate the importance of the specific nature of agglomerations in attracting inward investment. The article develops a model of FDI location choice using a unique FDI database stratified by industry and province. The results also suggest that the importance of agglomeration differs between industries, and offers some explanation for this

    Faint dwarf spheroidals in the Fornax Cluster: A flat luminosity function

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    We have discovered about 70 very faint dwarf galaxies in the Fornax Cluster. These dSphs candidates follow the same magnitude-surface brightness relation as their counterparts in the Local Group, and even extend it to fainter limits. The faintest dSph candidate in our sample has an absolute magnitude of M_V = -8.8 mag and a central surface brightness of mu_V = 27 mag/arcsec^2. There exists a tight color-magnitude relation for the early-type galaxies in Fornax that extends from the giant to the dwarf regime. The faint-end slope of the luminosity function of the early-type dwarfs is flat (alpha = -1.1+/-0.1), contrary to the results obtained by Kambas et al. (2000).Comment: 4 pages, 3 figures, accepted for publication in Astronomy & Astrophysics (Letters

    Superclusters of galaxies in the 2dF redshift survey. III. The properties of galaxies in superclusters

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    We use catalogues of superclusters of galaxies from the 2dF Galaxy Redshift Survey to study the properties of galaxies in superclusters. We compare the properties of galaxies in high and low density regions of rich superclusters, in poor superclusters and in the field, as well as in groups, and of isolated galaxies in superclusters of various richness. We show that in rich superclusters the values of the luminosity density smoothed on a scale of 8 \Mpc are higher than in poor superclusters: the median density in rich superclusters is δ≈7.5\delta \approx 7.5, in poor superclusters δ≈6.0\delta \approx 6.0. Rich superclusters contain high density cores with densities δ>10\delta > 10 while in poor superclusters such high density cores are absent. The properties of galaxies in rich and poor superclusters and in the field are different: the fraction of early type, passive galaxies in rich superclusters is slightly larger than in poor superclusters, and is the smallest among the field galaxies. Most importantly, in high density cores of rich superclusters (δ>10\delta > 10) there is an excess of early type, passive galaxies in groups and clusters, as well as among those which do not belong to groups or clusters. The main galaxies of superclusters have a rather limited range of absolute magnitudes. The main galaxies of rich superclusters have larger luminosities than those of poor superclusters and of groups in the field. Our results show that both the local (group/cluster) environments and global (supercluster) environments influence galaxy morphologies and their star formation activity.Comment: 13 pages, 10 figures, submitted to Astronomy and Astrophysic

    Mergers of luminous early-type galaxies in the local universe and gravitational wave background

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    Supermassive black hole (SMBH) coalescence in galaxy mergers is believed to be one of the primary sources of very low frequency gravitational waves (GWs). Significant contribution of the GWs comes from mergers of massive galaxies with redshifts z<2. Very few previous studies gave the merger rate of massive galaxies. % We selected a large sample (1209) of close pairs of galaxies with projected separations 7<r_p<50 kpc from 87,889 luminous early-type galaxies (M_r<-21.5) from the Sloan Digital Sky Survey Data Release 6. These pairs constitute a complete volume-limited sample in the local universe (z<0.12). Using our newly developed technique, 249 mergers have been identified by searching for interaction features. From them, we found that the merger fraction of luminous early-type galaxies is 0.8%, and the merger rate in the local universe is % R_g=(1.0+/-0.4)*10^{-5} Mpc^{-3} Gyr^{-1}} % with an uncertainty mainly depending on the merging timescale. % We estimated the masses of SMBHs in the centers of merging galaxies based on their luminosities. We found that the chirp mass distribution of the SMBH binaries follows a power law with an index of -3.0+/-0.5 in the range 5*10^8--5*10^{9} M_{\odot}. % Using the SMBH population in the mergers and assuming that the SMBHs can be efficiently driven into the GW regime, we investigated the stochastic GW background in the frequency range 10^{-9}--10^{-7} Hz. We obtained the spectrum of the GW background of h_c(f)=10^{-15}(f/yr^{-1})^{-2/3}, which is one magnitude higher than that obtained by Jaffe & Backer in 2003, but consistent with those calculated from galaxy-formation models.Comment: 27 pages, 9 figures, Corrected typos and reference
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