Astronomy and Astrophysics, volume 539A, 93-93 (2012/3-1)
MASSIV: Mass Assembly Survey with SINFONI In VVDS. III. Evidence for positive metallicity gradients in z∼1.2 star-forming galaxies.
QUEYREL J., CONTINI T., KISSLER-PATIG M., EPINAT B., AMRAM P., GARILLI B., LE FEVRE O., MOULTAKA J., PAIORO L., TASCA L., TRESSE L., VERGANI D., LOPEZ-SANJUAN C. and PEREZ-MONTERO E.
Abstract (from CDS):
The estimate of radial abundance gradients in high-redshift galaxies allows to constrain their star formation history and their interplay with the surrounding intergalactic medium. We present VLT/SINFONI integral-field spectroscopy of a first sample of 50 galaxies at z∼1.2 in the MASSIV survey. Using the N2 ratio between the [NII]6584 and Hα rest-frame optical emission lines as a proxy for oxygen abundance in the interstellar medium, we measured the metallicity of the sample galaxies. We developed a tool to extract spectra in annular regions, leading to a spatially resolved estimate of the oxygen abundance in each galaxy. We were able to derive a metallicity gradient for 26 galaxies in our sample and discovered a significant fraction of galaxies with a ``positive'' gradient. Using a simple chemical evolution model, we derived infall rates of pristine gas onto the disks. Seven galaxies display a positive gradient at a high confidence level. Four out of these are interacting, and one is a chain galaxy. We suggest that interactions might be responsible for shallowing and even inverting the abundance gradient. We also identify two interesting correlations in our sample: a) galaxies with higher gas velocity dispersion have shallower/positive gradients; and b) metal-poor galaxies tend to show a positive gradient, whereas metal-rich ones tend to show a negative one. This last observation can be explained by the infall of metal-poor gas into the center of the disks. We address the question of the origin of this infall under the influence of gas flows triggered by interactions and/or cold gas accretion. All the data published in this paper are publicly available at the time of publication following this link: http://cosmosdb.lambrate.inaf.it/VVDS-SINFONI
galaxies: evolution - galaxies: abundances - galaxies: high-redshift
View the reference in ADS
To bookmark this query, right click on this link: simbad:2012A&A...539A..93Q and select 'bookmark this link' or equivalent in the popup menu