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The Turbulent ISM of Galaxies 10 Gyrs ago: Star Formation, Gas Accretion, and IMF

Published online by Cambridge University Press:  05 December 2011

Loïc Le Tiran
Affiliation:
Laboratoire d'étude des Galaxies, Etoiles, Physique et Instrumentation GEPI, Observatoire de Paris, UMR8111 du CNRS, 92195 meudon, France
Matthew D. Lehnert
Affiliation:
Laboratoire d'étude des Galaxies, Etoiles, Physique et Instrumentation GEPI, Observatoire de Paris, UMR8111 du CNRS, 92195 meudon, France
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Abstract

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The utilization of integral-field spectroscopy has led us to a new understanding of the physical conditions in galaxies within the first few billion years after the Big Bang. In this proceedings, we analyze observations of ~50 massive galaxies as seen as they were 10 Gyrs ago using SINFONI from the ESO-VLT. We show that the large line width they exhibit can be explained by the intense mechanical energy output from the young stars. We also study the influence of cold gas accretion upon these galaxies: We show that an unrealistic amount of shocked gas would be needed in order to explain the Hα emission from these galaxies through shocks from gas accretion with velocity about the Hα line widths of these galaxies. We also use DEEP2 photometric measurements for a sub-sample of 10 of these galaxies to evaluate their ratio of Hα to FUV flux as a function of their Hα and R-band luminosity surface brightnesses. Our data suggests that perhaps their initial mass function (IMF) is flatter than Salpeter at the high mass end, as has been suggested recently for some local galaxies. It may be that high turbulence is responsible for skewing the IMF towards more massive stars as suggested by some theories of star-formation. Much work is however needed to accredit this hypothesis.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

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