3DLENS · 3D spectroscopy of lensing cluster fields

3D spectroscopy of lensing cluster fields

The 3DLENS project proposed to use the effect of gravitational lensing in combination with new spectro-imaging facilities to complete our picture of galaxy formation and evolution through the full characterization of a unique dataset of high redshift galaxies with resolved information, and a multiwavelength approach combining datasets from the optical to the radio wavelengths. We have used observations recently taken with integral field spectroscopy instruments on the Very Large Telescope to study the resolved properties of lensed galaxies highly magnified by massive galaxy clusters. One of the main challenges was to correct for the effet of magnification to reach the smallest physical scales in distant galaxies (between 100 pc and 1 kpc) per spatial element of resolution. We have developed new algorithms, made available publically, to perform these corrections and measure the morphology and kinematics of the gas in distant lensed galaxies. This modelling relied on the spectroscopic measurement of numerous multiple images in the same lensing clusters, which is feasible thanks to the large field of view and sensitivity of the instrument used, which covers the full strong lensing region of the cluster. Our measurements show that we are able to measure well-ordered velocity fields in such distant galaxies, showing that during the formation of isolated, less massive galaxies early in the Universe, the gas settled into disk-like structures, albeit more turbulent that their equivalent in more local galaxies. We have obtained dust and CO molecular gas observations covering the high magnification region of 2 massive clusters. These data allow us to detect the dust emission in highly magnified, distant low mass galaxies, with a signal-to-noise high enough to resolve the dust emission in the source plane. In addition, we have obtained the first detection of dust continuum in an extremely distant galaxy. Regarding CO gas measurements, single-dish and interferometric millimeter observations have allowed us to measure the molecular line transitions in distant low mass galaxies, opening a new parameter space in far-infrared bright, magnified galaxies. This was permitted thanks to the large collaboration gathering multiwavelength follow-ups in such galaxies. Finally we have started to study the carbon properties in very distant galaxies. A first pilot study has shown that low mass galaxies generally show reasonably strong carbon emission in the UV, extending the widely use Lyman-alpha studies to a different spectroscopic probe. We have then obtained the first carbon detection of an extremely distant galaxy and are now pursuing this study even further. Altogether, the 3DLENS project has allowed the fellow to attain a stable, independent permanent research position. He has now built his own research group and is coordinating new projects and supervising students, increasing the scientific expertise at the CRAL institute.

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