Examinando por Autor "Merrifield, M."

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Formation of S0s in extreme environments I: clues from kinematics and stellar populations
(Oxford Academics: Blackwell Publishing, 2020-02-01) Coccato, L.; Jaffé, Y. L.; Cortesi, A.; Merrifield, M.; Johnston, E. J.; Rodríguez del Pino, B.; Haeussler, B.; Chies Santos, A. L.; Mendes de Oliveira, Claudia L.; Sheen, Y. K.; Menéndez Delmestre, K.; Ministerio de Economía y Competitividad (MINECO); Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); National Research Foundation of Korea (NRF); Agencia Estatal de Investigación (AEI); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Rio Grande do Sul Research Foundation (FAPERGS); Jaffé, Y. L. [0000-0003-2150-1130]; Cortesi, A. [0000-0002-0620-136X]; Chies Santos, A. [0000-0003-3220-0165]; Mendes de Oliveira, C. [0000-0002-5267-9065]; Johnston, E. [0000-0002-2368-6469]; Merrifield, M. [0000-0002-4202-4727]; Rodríguez del Pino, B. [0000-0001-5171-3930]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
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.
Restringido
Formation of S0s in extreme environments II: The star-formation histories of bulges, discs, and lenses
(Oxford Academics: Oxford University Press, 2021-01-18) Johnston, E. J.; Aragón Salamanca, A.; Fraser-McKelvie, A.; Merrifield, M.; Häubler, B.; Coccato, L.; Jaffé, Y. L.; Cortesi, A.; Chies Santos, A.; Rodríguez del Pino, B.; Sheen, Y. K.; Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT); European Research Council (ERC); Comisión Nacional de Investigación Científica y Tecnológica (CONICYT); National Research Foundation of Korea (NRF); Jaffé, Y. [0000-0003-2150-1130]; Merrifield, M. [0000-0002-4202-4727]; Fraser McKelvie, A. [0000-0001-9557-5648]; Chies Santos, A. [0000-0003-3220-0165]; Aragón Salamanca, A. [0000-0001-8215-1256]
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 α-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.