The transformation of Spirals into S0 galaxies in the cluster environment

We discuss the observational evidences of the morphological transformation of Spirals into S0 galaxies in the cluster environment exploiting two big databases of galaxy clusters: WINGS (0.04 < z < 0.07) and EDisCS (0.4 < z < 0.8). The most important results are: 1) the average number of S0 galaxies in clusters is almost a factor of $\sim 3 - 4$ larger today than at redshift $z \sim 1$; 2) the fraction of S0's to Spirals increases on average by a factor $\sim$ 2 every Gyr; 3) the average rate of transformation for Spirals (not considering the infall of new galaxies from the cosmic web) is: $\sim$ 5 Sp into S0's per Gyr and $\sim$ 2 Sp into E's per Gyr; 4) there are evidences that the interstellar gas of Spirals is stripped by an hot intergalactic medium; 5) there are also indirect hints that major/minor merging events have played a role in the transformation of Spiral galaxies. In particular, we show that: 1) the ratio between the number of S0's and Spirals (NS0/NSp) in the WINGS clusters is correlated with their X-ray luminosity $L_X$ ; 2) that the brightest and massive S0's are always close to the cluster center; 3) that the mean Sersic index of S0's is always larger than that of Spirals (and lower than E's) for galaxy stellar masses above $10^9.5$ Msun; 4) that the number of E's in clusters cannot be constant; 5) that the largest difference between the mean mass of S0's and E's with respect to Spirals is observed in clusters with low velocity dispersion. Finally, by comparing the properties of the various morphological types for galaxies in clusters and in the field, we find that the most significant effect of the environment is the stripping of the outer galaxy regions, resulting in a systematic difference in effective radius and Sersic index.Comment: 38 pages, 20 figure

Librarianship Cooperation in the Field of Rare and Ancient Book, New Opportunities for the Padua University Libraries System

Cooperation has a long tradition in the working attitude of librarians. During the past 100 years words as collaboration, co-operation, resource- sharing have crossed and influenced all the main activities in the libraries. One of the oldest traditions in library cooperation has been the sharing of bibliographic information. Technology became the dominant factor in the design of cooperative systems for the acquisition, control and mobility of materials (OCLC, RLG). In the last years the main incentives to cooperate seem to be the rising material costs, and the proliferation of materials to purchase. A recent re-organization of the Padua University Libraries System (PULS) in 11 “Poli” offered the opportunity to establish an “Ancient and Special Collection Polo” with a coordinator (the researcher) and a small team of librarians managing the ancient and rare collections scattered in 50 libraries. Furthemore during the last 10 years formal relationships have been established with all others libraries of the city, almost all very rich in rare and ancient books. Nowadays they all share the same OPAC and some facilities in the ILL domain. In this context and in field of rare books and special collections, next step will be a mid-term planning of new activities, where cooperation should be one of the cornerstone. The rationale for selecting this particular problem is the researcher’s main working activity as coordinator of the Ancient and special Collection Polo in Padua University Libraries System and her commitment in planning future activities and the development of this particular Polo. To this end the project will provide information to allow the top management to develop a strategical, specific mid-term plan in the general context of the PULS

The Quest for the Dominant Stellar Population in the Giant Elliptical NGC 5018

Newly obtained HST/WFPC2 images of the disturbed elliptical galaxy NGC 5018 show that the average amount of internal reddening due to the its complex ``dust web'' is as low as E(B-V)~0.02 within the IUE aperture, thus implying that its observed and intrinsic energy distributions do not differ significantly down to UV wavelengths. This, in turn, is quite relevant to the current debate on the age of its dominant stellar population.Comment: 2 pages, 1 figure. Proceedings of the conference "Galaxy Disks and Disk Galaxies", ASP Conference Series, eds. J.G. Funes, S.J. and E.M. Corsin

Escoamento Óleo-Gás em Equipamento Submarino: Influência da Fração Volumétrica de Gás na Separação de Fases no Módulo de Bombeio

Resumo da dissertação: Nas bacias marítimas de petróleo do Estado do Espírito Santo são utilizados Módulos de Bombeio que interligam os poços produtores de petróleo aos navios-plataforma flutuantes de produção. Esses módulos possuem uma geometria capsular por onde escoa o petróleo, e onde podem ocorrer diversos padrões de escoamento multifásicos. Dependendo do padrão formado a separação das fases pode ocorrer provocando anomalias (por exemplo o chamado gas locking) no funcionamento da bomba submarina. O presente trabalho tem por objetivo verificar a influência da variação da fração volumétrica de gás, presente em um mistura (óleo-gás), no fenômeno de separação dessas fases. Para tanto foram simulados dois casos. O primeiro para uma fração volumétrica de gás de 10 %, e o segundo de 40 %. A vazão mássica utilizada de óleo foi de 8 kg s-1. Todas as simulações foram realizadas em um software CFD utilizando o modelo VOF (Volume of Fluid) explicito com número de Courant de 0,25 e passo de tempo de 4 x 10-5 s. Três diferentes malhas foram avaliadas com relação à convergência e ao tamanho do elemento, sempre priorizando uma possível formação de interface nítida entre os fluidos. Para o primeiro caso, 10 % de fração de volume, não houve separação nítida das fases e sim a formação de um padrão de escoamento assimétrico, indicado pelos perfis de velocidade obtidos em várias posições e planos. A ordem de velocidade em um setor da cápsula varia de 7 m s-1 na entrada e 1,2 m s-1 a 2,5 diâmetros de comprimento. Por outro lado, para a fração de volume de 40 %, uma nítida interface é formada e gás acumulado no topo da cápsula. Neste caso, em 2,5 diâmetros de comprimento de cápsula, a porcentagem de gás acumulada em 4.2 s de tempo real é de 90 % da quantidade entrante na cápsula. Os níveis de velocidade variaram entre 9.8 m s-1 na entrada e 0.15 m s-1 a 2,5 diâmetros de comprimento. As considerações finais sugerem que simulações sejam realizadas para obtenção de tempos reais da ordem de minuto, pois a cápsula possui 50 diâmetros equivalentes de comprimento. Palavras chave: VOF, multifásico, BCSS, módulo de bombeio, equipamento submarino

Galaxy Evolution in Local Group Analogs. I. A GALEX study of nearby groups

Understanding the astrophysical processes acting within galaxy groups and their effects on the evolution of the galaxy population is one of the crucial topic of modern cosmology, as almost 60% of galaxies in the Local Universe are found in groups. We imaged in the far (FUV 1539 A) and near ultraviolet (NUV 2316 A) with GALEX three nearby groups, namely LGG93, LGG127 and LGG225. We obtained the UV galaxy surface photometry and, for LGG225, the only group covered by the SDSS, the photometry in u, g, r, i, z bands. We discuss galaxy morphologies looking for interaction signatures and we analyze the SED of galaxies to infer their luminosity-weighted ages. The UV and optical photometry was also used to perform a kinematical and dynamical analysis of each group and to evaluate the stellar mass. A few member galaxies in LGG225 show a distorted UV morphology due to ongoing interactions. (FUV-NUV) colors suggest that spirals in LGG93 and LGG225 host stellar populations in their outskirts younger than that of M31 and M33 in the LG or with less extinction. The irregular interacting galaxy NGC3447A has a significantly younger stellar population (few Myr old) than the average of the other irregular galaxies in LGG225 suggesting that the encounter triggered star formation. The early-type members of LGG225, NGC3457 and NGC3522, have masses of the order of a few 10^9 Mo, comparable to the Local Group ellipticals. For the most massive spiral in LGG225, we estimate a stellar mass of ~4x10$^{10}$ Mo, comparable to M33 in the LG. Ages of stellar populations range from a few to ~7 Gyr for the galaxies in LGG225. The kinematical and dynamical analysis indicates that LGG127 and LGG225 are in a pre-virial collapse phase, i.e. still undergoing dynamical relaxation, while LGG93 is likely virialized. (Abridged)Comment: 20 pages, 13 figures, accepted for publication in Astronomy and Astrophysic

Fermi-LAT Observations of the 2014 May-July outburst from 3C 454.3

A prominent outburst of the flat spectrum radio quasar 3C~454.3 was observed in 2014 June with the \emph{Fermi} Large Area Telescope. This outburst was characterized by a three-stage light-curve pattern---plateau, flare and post-flare---that occurred from 2014 May to July, in a similar pattern as observed during the exceptional outburst in 2010 November. The highest flux of the outburst reported in this paper occurred during 2014 June 7--29, showing a multiple-peak structure in the light-curves. The average flux in these 22 days was found to be $F[E > 100~\mathrm{MeV}] = (7.2 \pm 0.2) \times 10^{-6}$~ph~cm$^{-2}$~s$^{-1}$, with a spectral index, for a simple power law, of $\Gamma = 2.04 \pm 0.01$. That made this outburst the first $\gamma$-ray high state of 3C~454.3 ever to be detected by \emph{Fermi} with such a hard spectrum over several days. The highest flux was recorded on 2014 June 15, in a 3 hr bin, at MJD 56823.5625, at a level of $F[E > 100~\mathrm{MeV}] = (17.6 \pm 1.9) \times 10^{-6}$~ph~cm$^{-2}$~s$^{-1}$. The rise time of one of the short subflares was found to be $T_r= 1200 \pm 700$~s at MJD = 56827, when the flux increased from 4 to 12 $\times 10^{-6}$~ph~cm$^{-2}$~s$^{-1}$. Several photons above 20 GeV were collected during this outburst, including one at 45 GeV on MJD 56827, constraining the $\gamma$-ray emission region to be located close to the outer boundary of the broad-line region, leading to fast flux variability.Comment: Accepted for publication in {\sc the astrophysical journal}: 2016 July 12}; 15 pages, 7 figures, 6 table