Examinando por Autor "Franchetto, Andrea"

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  • Miniatura
    Ítem
    GASP XXIX - Unwinding the arms of spiral galaxies via ram-pressure stripping
    (Royal Astronomical Society, 2021) Bellhouse, Callum; Mcgee, Sean L; Smith, Rory; Poggianti, Bianca M; Jaffé, Yara L; Kraljic, Katarina; Franchetto, Andrea; Fritz, Jacopo; Vulcani, Benedetta; Tonnesen, Stephanie; Roediger, Elke; Moretti, Alessia; Gullieuszik, Marco; Shin, Jihye
    We present the first study of the effect of ram pressure ‘unwinding’ the spiral arms of cluster galaxies. We study 11 ram-pressure stripped galaxies from GASP (GAs Stripping Phenomena in galaxies) in which, in addition to more commonly observed ‘jellyfish’ features, dislodged material also appears to retain the original structure of the spiral arms. Gravitational influence from neighbours is ruled out and we compare the sample with a control group of undisturbed spiral galaxies and simulated stripped galaxies. We first confirm the unwinding nature, finding that the spiral arm pitch angle increases radially in 10 stripped galaxies and also simulated face-on and edge-on stripped galaxies. We find only younger stars in the unwound component, while older stars in the disc remain undisturbed. We compare the morphology and kinematics with simulated ram-pressure stripping galaxies, taking into account the estimated inclination with respect to the intracluster medium (ICM) and find that in edge-on stripping, unwinding can occur due to differential ram pressure caused by the disc rotation, causing stripped material to slow and ‘pile up’. In face-on cases, gas removed from the outer edges falls to higher orbits, appearing to ‘unwind’. The pattern is fairly short-lived (<0.5 Gyr) in the stripping process, occurring during first infall and eventually washed out by the ICM wind into the tail of the jellyfish galaxy. By comparing simulations with the observed sample, we find that a combination of face-on and edge-on ‘unwinding’ effects is likely to be occurring in our galaxies as they experience stripping with different inclinations with respect to the ICM.
  • Miniatura
    Ítem
    GASP XXXIII. The ability of spatially resolved data to distinguish among the diferent physical mechanisms afecting galaxies in low-density environments
    (American Astronomical Society (Aas), 2021) Vulcani, Benedetta; Poggianti, Bianca M.; Moretti, Alessia; Franchetto, Andrea; Bacchini, Cecilia; Mcgee, Sean; Jaffé, Yara L.; Mingozzi, Matilde; Werle, Ariel; Tomičić, Neven; Fritz, Jacopo; Bettoni, Daniela; Wolter, Anna; Gullieuszik, Marco
    Galaxies inhabit a wide range of environments and therefore are affected by different physical mechanisms. Spatially resolved maps combined with the knowledge of the hosting environment are very powerful for classifying galaxies by physical process. In the context of the GAs Stripping Phenomena in galaxies (GASP), we present a study of 27 non-cluster galaxies: 24 of them were selected for showing asymmetries and disturbances in the optical morphology, suggestive of gas stripping; 3 of them are passive galaxies and were included to characterize the final stages of galaxy evolution. We therefore provide a panorama of the different processes taking place in low-density environments. The analysis of VLT/MUSE data allows us to separate galaxies into the following categories: galaxy–galaxy interactions (2 galaxies), mergers (6), ram pressure stripping (4), cosmic web stripping (2), cosmic web enhancement (5), gas accretion (3), and starvation (3). In one galaxy we identify the combination of merger and ram pressure stripping. Only 6/27 of these galaxies have just a tentative classification. We then investigate where these galaxies are located on scaling relations determined for a sample of undisturbed galaxies. Our analysis shows the successes and limitations of a visual optical selection in identifying the processes that deplete galaxies of their gas content and probes the power of IFU data in pinning down the acting mechanism.