Showing papers by "A. Iovino published in 1996"
74 citations
TL;DR: In this article, the authors compared the results of the automated quasar detection (AQD) technique with the Veron & Veron catalogue (1993) and the Cristiani et al. compilation (1995) and showed that AQD re-discovered % of the known quasars with non-overlapping objective-prism spectra present in these fields.
Abstract: The Automated Quasar Detection (AQD) technique has been applied to six connected fields near the South Galactic Pole. A comparison with the Veron & Veron catalogue (1993) and the Cristiani et al. compilation (1995) shows that AQD re–discovered % of the known quasars with non–overlapping objective–prism spectra present in these fields (% if only the high probability candidates are considered). A list of the 1592 high probability candidates is given, including the results of cross–correlation with X–ray and radio catalogues.
22 citations
TL;DR: In this paper, it was shown that the variation of the B - K colour of galaxies as a function of the morphological types can explain the observed blue galaxy counts without invoking strong luminosity and/or density evolution.
Abstract: Standard models for deep galaxy counts are based on luminosity functions (LFs) that have a relatively flat faint end «(X '" - 1.0). Galaxy counts in the B band exceed the prediction of such models from a factor of 2 to more than a factor of 5, forcing the introduction of strong luminosity and/or density evolution. Recently Marzke, Huchra & Geller, using the CfA redshift survey sample, found that the number of galaxies in the range - 16 < M Zw < - 13 exceeds the extrapolation of a flat faint-end LF by a factor of 2. Here we show that this steep LF substantially contributes to justify the observed blue galaxy counts without invoking strong luminosity and/or density evolution. Furthermore we show that taking into account the variation of the B - K colour as a function of the morphological types and assuming a mean value (B - K) < 2.5 for dwarf galaxies, we reproduce well also the observed K-band deep galaxy counts. This assumption is supported by the strong correlation we found between B - K colour of galaxies and their infrared absolute magnitude: galaxies become bluer with decreasing luminosity.
3 citations
01 Jan 1996
TL;DR: The discovery of gravitationally lensed radio-rings (Hewitt et al. 1988) opened up a new line of attack on the problem of dark matter in galaxies as discussed by the authors.
Abstract: The discovery of gravitationally lensed radio-rings (Hewitt et al. 1988) opened up a new line of attack on the problem of dark matter in galaxies. High-resolution radio observations (Langston et al. 1989) resolve structure tangentially and radially within the rings, providing sophisticated analysis routines (Kochanek & Narayan 1992, Wallington, Narayan & Kochanek 1994) with enough constraints to compute realistic models of the mass distribution within the deflectors (Kochanek 1995). Five such systems are now known and extensive programs to identify further examples are underway.