Astronomy and Astrophysics, volume 492, 371-388 (2008/12-3)
IMAGES IV: strong evolution of the oxygen abundance in gaseous phases of intermediate mass galaxies from z∼0.8.
RODRIGUES M., HAMMER F., FLORES H., PUECH M., LIANG Y.C., FUENTES-CARRERA I., NESVADBA N., LEHNERT M., YANG Y., AMRAM P., BALKOWSKI C., CESARSKY C., DANNERBAUER H., DELGADO R., GUIDERDONI B., KEMBHAVI A., NEICHEL B., OESTLIN G., POZZETTI L., RAVIKUMAR C.D., RAWAT A., DI SEREGO ALIGHIERI S., VERGANI D., VERNET J. and WOZNIAK H.
Abstract (from CDS):
Intermediate mass galaxies (>1010M☉) at z∼0.6 are the likeliest progenitors of the present-day, numerous population of spirals. There is growing evidence that they have evolved rapidly in the last 6 to 8 Gyr, and likely already have formed a significant fraction of their stellar mass, often showing perturbed morphologies and kinematics. We have gathered a representative sample of 88 such galaxies and have provided robust estimates of their gas phase metallicity. We used moderate spectral resolution spectroscopy at VLT/FORS2 with an unprecedentedly high S/N allowing us to remove biases coming from interstellar absorption lines and extinction, to establish robust values of R23=([OII]λ3727+[OIII]λλ4959,5007)/Hβ.We definitively confirm that the predominant population of z∼0.6 starbursts and luminous IR galaxies (LIRGs) are on average two times less metal rich than the local galaxies at a given stellar mass. We do find that the metal abundance of the gaseous phase of galaxies evolves linearly with time, from z=1 to z=0 and after comparing with other studies, from z=3 to z=0. Combining our results with the reported evolution of the Tully Fisher relation, we find that such an evolution requires that ∼30% of the stellar mass of local galaxies have been formed through an external supply of gas, thus excluding the closed box model. Distant starbursts & LIRGs have properties (metal abundance, star formation efficiency & morphologies) similar to those of local LIRGs. Their underlying physics is likely dominated by gas infall, probably through merging or interactions. Our study further supports the rapid evolution of z∼0.4-1 galaxies. Gas exchange between galaxies is likely the main cause of this evolution.
galaxies: evolution - galaxies: ISM - galaxies: spiral - galaxies: starburst - infrared: galaxies
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