Browsing by Author "La Barbera, Francesco"

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    Building the Largest Spectroscopic Sample of Ultracompact Massive Galaxies with the Kilo Degree Survey
    (IOP PUBLISHING LTD, 2020) Scognamiglio, Diana; Tortora, Crescenzo; Spavone, Marilena; Spiniello, Chiara; Napolitano, Nicola R.; D'Ago, Giuseppe; La Barbera, Francesco; Getman, Fedor; Roy, Nivya; Raj, Maria Angela; Radovich, Mario; Brescia, Massimo; Cavuoti, Stefano; Koopmans, Leon V. E.; Kuijken, Koen H.; Longo, Giuseppe; Petrillo, Carlo Enrico
    Ultracompact massive galaxies (UCMGs), i.e., galaxies with stellar masses M. > 8 ' 1010M. and effective radii Re < 1.5 kpc, are very rare systems, in particular at low and intermediate redshifts. Their origin as well as their number density across cosmic time are still under scrutiny, especially because of the paucity of spectroscopically confirmed samples. We have started a systematic census of UCMG candidates within the ESO Kilo Degree Survey, together with a large spectroscopic follow-up campaign to build the largest possible sample of confirmed UCMGs. This is the third paper of the series and the second based on the spectroscopic follow-up program. Here, we present photometrical and structural parameters of 33 new candidates at redshifts 0.15. z. 0.5 and confirm 19 of them as UCMGs, based on their nominal spectroscopically inferred M. and Re. This corresponds to a success rate of 58%, nicely consistent with our previous findings. The addition of these 19 newly confirmed objects allows us to fully assess the systematics on the system selection-and to finally reduce the number density uncertainties. Moreover, putting together the results from our current and past observational campaigns and some literature data, we build the largest sample of UCMGs ever collected, comprising 92 spectroscopically confirmed objects at 0.1. z. 0.5. This number raises to 116, allowing for a 3s tolerance on the M. and Re thresholds for the UCMG definition. For all these galaxies, we have estimated the velocity dispersion values at the effective radii, which have been used to derive a preliminary mass-velocity dispersion correlation.
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    The elemental abundance of quiescent galaxies in the LEGA-C survey: the (non-)evolution of [α/Fe] from z=0.75 to z=0
    (2023) Bevacqua, Davide; Saracco, Paolo; La Barbera, Francesco; D'Ago, Giuseppe; De Propris, Roberto; Ferreras, Ignacio; Gallazzi, Anna; Pasquali, Anna; Spiniello, Chiara
    We measure the [alpha/Fe] abundances for 183 quiescent galaxies at z = 0.60-0.75 with stellar masses ranging 10.4 <= log(10)(M-*/M-circle dot) <= 11.6 selected from the Large Early Galaxy Astrophysics Census survey. We estimate [alpha/Fe] from the ratio of the spectral indices Mgb (lambda similar to 5177 angstrom) and Fe4383, compared to predictions of simple stellar population models. We find that 91 percent of quiescents in our sample have supersolar [alpha/Fe], with an average value of [alpha/Fe] = +0.24 +/- 0.01. We find no significant correlation between [alpha/Fe] and stellar metallicity, mass, velocity dispersion, and average formation time. Galaxies that formed the bulk of their stellar mass on time-scales shorter than 1 Gyr follow the same [alpha/Fe] distribution as those which formed on longer time-scales. In comparison to local early-type galaxies and to stacked spectra of quiescent galaxies at z = 0.38 and z = 0.07, we find that the average [alpha/Fe] has not changed between z = 0.75 and the present time. Our work shows that the vast majority of massive quiescent galaxies at z similar to 0.7 are alpha-enhanced, and that no detectable evolution of the average [alpha/Fe] has taken place over the last similar to 6.5 Gyr.
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    VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems Testing the methodology on the globular cluster system in NGC 3115
    (2015) Cantiello, Michele; Capaccioli, Massimo; Napolitano, Nicola; Grado, Aniello; Limatola, Luca; Paolillo, Maurizio; Iodice, Enrica; Romanowsky, Aaron J.; Forbes, Duncan A.; Puzia, Thomas H.; Spavone, Marilena; La Barbera, Francesco; Raimondo, Gabriella; Schipani, Pietro