Browsing by Author "Coccato, Lodovico"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    BUDDI-MaNGA II: the star-formation histories of bulges and discs of S0s
    (OXFORD UNIV PRESS, 2022) Johnston, Evelyn J.; Haussler, Boris; Jegatheesan, Keerthana; Fraser-McKelvie, Amelia; Coccato, Lodovico; Cortesi, Arianna; Jaffe, Yara; Galaz, Gaspar; Mora, Marcelo; Ordenes-Briceno, Yasna
    Many processes have been proposed to explain the quenching of star formation in spiral galaxies and their transformation into S0s. These processes affect the bulge and disc in different ways, and so by isolating the bulge and disc spectra, we can look for these characteristic signatures. In this work, we used BUDDI to cleanly extract the spectra of the bulges and discs of 78 S0 galaxies in the MaNGA Survey. We compared the luminosity and mass weighted stellar populations of the bulges and discs, finding that bulges are generally older and more metal rich than their discs. When considering the mass and environment of each galaxy, we found that the galaxy stellar mass plays a more significant role on the formation of the bulges. Bulges in galaxies with masses >= 10(10) M-circle dot built up the majority of their mass rapidly early in their lifetimes, while those in lower mass galaxies formed over more extended time-scales and more recently. No clear difference was found in the formation or quenching processes of the discs as a function of galaxy environment. We conclude that more massive S0 galaxies formed through an inside-out scenario, where the bulge formed first and evolved passively while the disc underwent a more extended period of star formation. In lower mass S0s, the bulges and discs either formed together from the same material, or through an outside-in scenario. Our results therefore imply multiple formation mechanisms for S0 galaxies, the pathway of which is chiefly determined by a galaxy's current stellar mass.
  • No Thumbnail Available
    Item
    Formation of S0s in extreme environments I: clues from kinematics and stellar populations
    (2020) Coccato, Lodovico; Jaffe, Yara L.; Cortesi, Arianna; Merrifield, Michael; Johnston, Evelyn; Rodriguez del Pino, Bruno; Haeussler, Boris; Chies-Santos, Ana L.; Mendes de Oliveira, Claudia L.; Sheen, Yun-Kyeong; Menendez-Delmestre, Karin
    Despite numerous efforts, it is still unclear whether lenticular galaxies (S0s) evolve from spirals whose star formation was suppressed, or formed trough mergers or disc instabilities. In this paper we present a pilot study of 21 S0 galaxies in extreme environments (field and cluster), and compare their spatially resolved kinematics and global stellar populations. Our aim is to identify whether there are different mechanisms that form S0s in different environments. Our results show that the kinematics of S0 galaxies in field and cluster are, indeed, different. Lenticulars in the cluster are more rotationally supported, suggesting that they are formed through processes that involve the rapid consumption or removal of gas (e.g. starvation, ram pressure stripping). In contrast, S0s in the field are more pressure supported, suggesting that minor mergers served mostly to shape their kinematic properties. These results are independent of total mass, luminosity, or disc-to-bulge ratio. On the other hand, the mass-weighted age, metallicity, and star formation time-scale of the galaxies correlate more with mass than with environment, in agreement with known relations from previous work, such as the one between mass and metallicity. Overall, our results re-enforce the idea that there are multiple mechanisms that produce S0s, and that both mass and environment play key roles. A larger sample is highly desirable to confirm or refute the results and the interpretation of this pilot study.
  • No Thumbnail Available
    Item
    Formation of S0s in extreme environments II: The star-formation histories of bulges, discs, and lenses
    (2021) Johnston, Evelyn J.; Aragon-Salamanca, Alfonso; Fraser-McKelvie, Amelia; Merrifield, Michael; Haeussler, Boris; Coccato, Lodovico; Jaffe, Yara; Cortesi, Ariana; Chies-Santos, Ana; Rodriguez Del Pino, Bruno; Sheen, Yun-Kyeong
    Different processes have been proposed to explain the formation of S0s, including mergers, disc instabilities, and quenched spirals. These processes are expected to dominate in different environments, and thus leave characteristic footprints in the kinematics and stellar populations of the individual components within the galaxies. New techniques enable us to cleanly disentangle the kinematics and stellar populations of these components in IFU observations. In this paper, we use BUDDI to spectroscopically extract the light from the bulge, disc, and lens components within a sample of eight S0 galaxies in extreme environments observed with MUSE. While the spectra of bulges and discs in S0 galaxies have been separated before, this work is the first to isolate the spectra of lenses. Stellar populations analysis revealed that the bulges and lenses have generally similar or higher metallicities than the discs, and the alpha-enhancement of the bulges and discs are correlated, while those of the lenses are completely unconnected to either component. We conclude that the majority of the mass in these galaxies was built up early in the lifetime of the galaxy, with the bulges and discs forming from the same material through dissipational processes at high redshift. The lenses, on the other hand, formed over independent time-scales at more random times within the lifetime of the galaxy, possibly from evolved bars. The younger stellar populations and asymmetric features seen in the field S0s may indicate that these galaxies have been affected more by minor mergers than the cluster galaxies.
  • No Thumbnail Available
    Item
    Mapping the Kinematically Decoupled Core in NGC 1407 with MUSE
    (2018) Johnston, Evelyn J.; Hau, George K. T.; Coccato, Lodovico; Herrera, Cristian
    Studies of the kinematics of NGC 1407 have revealed complex kinematical structure, consisting of the outer galaxy, an embedded disc within a radius of similar to 60 arcsec, and a kinematically decoupled core (KDC) with a radius of less than 30 arcsec. However, the size of the KDC and the amplitude of the kinematic misalignment it induces have not yet been determined. In this paper, we explore the properties of the KDC using observations from the Multi-Unit Spectroscopic Explorer (MUSE) Integral Field Spectrograph to map out the kinematics in the central arcminute of NGC 1407. Velocity and kinemetry maps of the galaxy reveal a twist of similar to 148 degrees in the central 10 arcsec of the galaxy, and the higher order moments of the kinematics reveal that within the same region, this slowly rotating galaxy displays no net rotation. Analysis of the stellar populations across the galaxy found no evidence of younger stellar populations in the region of the KDC, instead finding uniform age and super-solar a-enhancement across the galaxy, and a smoothly decreasing metallicity gradient with radius. We therefore conclude that NGC 1407 contains a triaxial, kiloparsec-scale KDC with distinct kinematics relative to the rest of the galaxy, and that is likely to have formed through either a major merger or a series of minor mergers early in the lifetime of the galaxy. With a radius of similar to 5 arcsec or similar to 0.6 kpc, NGC 1407 contains the smallest KDC mapped by MUSE to date in terms of both its physical and angular size.