JCJC - Jeunes chercheuses & jeunes chercheurs

The assembly of galaxies along cosmic time from SINFONI 3D spectroscopic observations of a complete sample of high-redshift 1 < z < 1.8 galaxies – AGACTS

Submission summary

A key question in the formation and evolution of galaxies is the epoch and mechanisms of mass assembly. Proging the dynamics, and hence the gravitational mass, of high-redshift galaxies is crucial for this purpose but is limited, up to now, to a few limited-size samples. We propose in this project to measure the velocity field of a large sample of star-forming galaxies in the redshift range 1.0<z<1.8 where rapid changes in the galaxy populations are observed. To reach this ambitious goal, we obtained 300 hours of observing time with the AO-assisted near-infrared integral-field spectrograph SINFONI on the VLT. This 'Large Program' (PI: Thierry Contini) will last for over two years, with the first run of observations scheduled in spring 2007. For this program, we have selected a unique sample of 138 galaxies from the VIMOS VLT Deep Survey (VVDS), which is both statistically representative of the overall population and volume complete, based on the measured stellar masses and on-going star formation rate. The VVDS is the only survey with enough galaxies with known spectroscopic redshifts in the range 1<z<1.8 to enable to identify a statistically significant and volume complete sub-sample of galaxies with both H&#61537; in emission, and with this line positioned well between the OH sky lines to enable its use for accurate velocity measurements. Our first observations demonstrate the great prospects of this program to quantify the internal dynamics of galaxies at these epochs, including rotation curves, bulk gas motions, interactions with close neighbours and mergers, spatially-resolved ISM metallicity, thus establishing for each galaxy whether it is a likely precursor of a big spiral or of a massive spheroid. The velocity field measured with SINFONI will enable to compute the total dynamical mass of each galaxy, while all studies at these epochs have only been able to indirectly measure the stellar mass, and therefore it will allow us to probe the evolution in total mass, mass-to-light ratio and metallicity, to measure the evolution of the Tully-Fisher and mass-metallicity relations, therefore setting unprecedented constraints on the formation and evolution of galaxies. This dataset is a needed complement to on-going programs at lower and higher redshifts to probe the assembly of mass at the peak of star formation activity.

Project coordination

Thierry CONTINI (Université)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Help of the ANR 148,300 euros
Beginning and duration of the scientific project: - 36 Months

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