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Session 21 - Luminous Infrared Galaxies.
Display session, Wednesday, January 07
Exhibit Hall,
The MPE Near-IR imaging spectrometer 3D is a new type of instrument which can simultaneously obtain 256 H-band or K-band spectra at R = \lambda/\Delta\lambda = 1000 or R = \lambda/\Delta\lambda = 2000 from a 16\times 16 pixel field in the sky (pixel scale= 0.3^\prime\prime--0.5^\prime\prime). Observations of ultraluminous infrared galaxies made with this instrument (and its associated tip-tilt corrector ROGUE) have been complimented with measurements made with the Plateau de Bure Interferometer (PdBI), which provides millimeter data of similar spatial resolution and superior spectral resolution.
With these two instruments we now have the ability to study in detail the spatial variation of the stellar velocity dispersion, the stellar population characteristics, and the morphology and dynamics of both the hot and cold components of the interstellar medium. These measures lead to an understanding of, for example, the location of the dynamical center of merging systems, as well as to the mass distribution in the central regions of these ultraluminous systems.
In the case of NGC\,6240, our CO bandhead measurements show that the dynamical center of this advanced merger lies between the nuclei, near the position of the H_2 peak. The millimeter CO observations of UGC\,5101 indicate that there is a dynamical mass of 3.1\,\times\,10^10\,M_ødot within the central kiloparsec. Combining this with the NIR spectroscopy we find that half of this dynamical mass is in the form of gas.
