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"Trigger mechanisms and evolution of ultra-luminous IR galaxies: local vs high-z"
Dr. Kalliopi Dasyra
Spitzer Science Center
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When:  Friday 12 September 2008 at noon
Where: 2nd Floor Seminar Room

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Abstract:

IR-luminous galaxies play an important role in driving galaxy evolution, since
the excess of IR emission is often associated with interactions. I will summarize
results from programs that aimed to reveal the nature of IR-luminous galaxies at
different redshift ranges. A Very Large Telescope NIR spectroscopic program that
provided stellar kinematic measurements in ~50 local ultraluminous IR galaxies
(ULIRGs) revealed that they are typically triggered by comparable mass mergers of
gas-rich galaxies and that they lead to formation of moderate-mass ellipticals.
At z~2, Hubble Space Telescope images of 24 micron-selected ULIRGs, which have
similar  MIR spectra to those of local ULIRGs, show small fraction of perturbations
with respect to both local ULIRGs and z~2 submm galaxies. This result could be
attributed to selection effects or to differences in the stellar/gas mass content
and distribution of these populations. A bulge-to-disk decomposition indicates 
that bright z~2 ULIRGs have small or negligible bulges, in contrast to their
local analogues. We are presently obtaining Spitzer MIR spectra and Hubble NIR
images of sources in the redshift range [0.05,3.5] to investigate for evolution
in the trigger mechanisms of IR excess emission with z. Studies of obscured
black hole growth with z can be enabled through high-resolution MIR spectroscopy
in combination with the fundamental relation between the mass of a black hole
and the velocity dispersion of the stars in its host-galaxy bulge. I will show
how the calibration of this relation at high luminosities, which are similar
to those of AGN that we observe at  high z,  can be achieved through NIR
spectroscopy assisted by adaptive optics.

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Kalliopi Dasyra
Postdoctoral Scholar
Spitzer Science Center
(dasyra@ipac.caltech.edu)
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