Examinando por Autor "Paolillo, Maurizio"

Mostrando 1 - 2 de 2
  • Miniatura
    Ítem
    Globular cluster scale sizes in giant galaxies: orbital anisotropy and tidally underfilling clusters in M87, NGC 1399 and NGC 5128
    (OXFORD UNIV PRESS, 2016-08) Webb, Jeremy J.; Sills, Alison; Harris, William E.; Gómez, Matías; Paolillo, Maurizio; Woodley, Kristin A.; Puzia, Thomas H.
    We investigate the shallow increase in globular cluster half-light radii with projected galactocentric distance Rgc observed in the giant galaxies M87, NGC 1399, and NGC 5128. To model the trend in each galaxy, we explore the effects of orbital anisotropy and tidally underfilling clusters. While a strong degeneracy exists between the two parameters, we use kinematic studies to help constrain the distance Rβ beyond which cluster orbits become anisotropic, as well as the distance Rfα beyond which clusters are tidally underfilling. For M87 we find Rβ > 27 kpc and 20 < Rfα < 40 kpc and for NGC 1399 Rβ > 13 kpc and 10 < Rfα < 30 kpc. The connection of Rfα with each galaxy's mass profile indicates the relationship between size and Rgc may be imposed at formation, with only inner clusters being tidally affected. The best-fitting models suggest the dynamical histories of brightest cluster galaxies yield similar present-day distributions of cluster properties. For NGC 5128, the central giant in a small galaxy group, we find Rβ > 5 kpc and Rfα > 30 kpc. While we cannot rule out a dependence on Rgc, NGC 5128 is well fitted by a tidally filling cluster population with an isotropic distribution of orbits, suggesting it may have formed via an initial fast accretion phase. Perturbations from the surrounding environment may also affect a galaxy's orbital anisotropy profile, as outer clusters in M87 and NGC 1399 have primarily radial orbits while outer NGC 5128 clusters remain isotropic.
  • Miniatura
    Ítem
    Weak lensing study in VOICE survey - II. Shear bias calibrations
    (Oxford University Press, 2018-08) Liu, Dezi; Fu, Liping; Liu, Xiangkun; Radovich, Mario; Wang, Chao; Pan, Chuzhong; Fan, Zuhui; Covone, Giovanni; Vaccari, Mattia; Botticella, Maria Teresa; Capaccioli, Massimo; De Cicco, Demetrae Grado, Aniello; Miller, Lance; Napolitano, Nicola; Paolillo, Maurizio; Pignata, Giuliano
    The VST Optical Imaging of the CDFS and ES1 Fields (VOICE) Survey is proposed to obtain deep optical ugri imaging of the CDFS and ES1 fields using the VLT Survey Telescope (VST). At present, the observations for the CDFS field have been completed, and comprise in total about 4.9 deg2 down to rAB~26 mag. In the companion paper by Fu et al., we present the weak lensing shear measurements for r-band images with seeing ≤0.9 arcsec. In this paper, we perform image simulations to calibrate possible biases of the measured shear signals. Statistically, the properties of the simulated point spread function and galaxies show good agreements with those of observations. The multiplicative bias is calibrated to reach an accuracy of ~3.0 per cent. We study the bias sensitivities to the undetected faint galaxies and to the neighbouring galaxies. We find that undetected galaxies contribute to the multiplicative bias at the level of ~0.3 per cent. Further analysis shows that galaxies with lower signal-to-noise ratio are impacted more significantly because the undetected galaxies skew the background noise distribution. For the neighbouring galaxies, we find that although most have been rejected in the shape measurement procedure, about one-third of them still remain in the final shear sample. They show a larger ellipticity dispersion and contribute to ~0.2 per cent of the multiplicative bias. Such a bias can be removed by further eliminating these neighbouring galaxies. But the effective number density of the galaxies can be reduced considerably. Therefore efficient methods should be developed for future weak lensing deep surveys. © 2018 The Author(s).