Galaxy formation and evolution

Abstract:

We demonstrate the possibility of detecting mass concentrations (down to the level of 5 x 10(7) M.) in the center of galaxies with ground-based optical telescopes properly equipped, using Keplerian gaseous disks as probes. We predict that the high spatial resolution of HST equipped with STIS will allow to detect central mass concentrations down to the level of 5 x 10(6) M.. As a consequence, the detection of low mass concentrations in the range 10(6) - 10(7) M. will constitute a very appropriate use of HST.

Abstract:

Spectroscopy from the Infrared Space Observatory ISO has for the first time provided the sensitivity to exploit the diagnostic power of mid-infrared fine structure lines and PAH features for the study of ultraluminous infrared galaxies (L-IR > 10(12)L.). We report on observations obtained with SWS, ISOPHOT-S, and the CVF option of ISOCAM. From both fine structure lines and PAH features, we find that the majority of ULIRGs is predominantly powered by star formation. Our total sample of about 75 ULIRGs allows to search for trends within the class of ULIRGs: The fraction of AGNs increases with luminosity above similar to 3 x 10(12)L. but there is no obvious trend for ULIRGs to be more AGN-like with more advanced merger phase.

Abstract:

We present spectroscopic mid-IR observations of prominent starburst galaxies obtained with the short wavelength spectrometer onboard the Infrared Space Observatory. The wavelength range accessible by ISO-sws (2.5-45 pm) contains a large number of emission lines of atomic and molecular hydrogen and several other atomic species. In this paper we discuss the interpretation of the [NeIII] 15.5 mum/[NeII] 12.8 mum line-ratio, the faint [OIV] 25.9 mum line and the pure rotational lines of molecular hydrogen observed in our target galaxies.

Abstract:

The technique of integral field spectroscopy,: which provides simultaneous spectra for each pixel of a contiguous two-dimensional field of view, holds tremendous promise for improving our ability to study circumstellar environments. The technique becomes especially important at near infrared wavelengths, where rapid changes in the night sky background level limit the use of standard scanning techniques. In addition, combining the capabilities of adaptive optics systems with near infrared integral field spectrographs provides an unique way to enhance-spatial resolution for ground based observations. We present the technique of integral field spectroscopy, with special emphasis on the near infrared, and illustrate future developments by describing SINFONI, an adaptive optics assisted near infrared integral field spectrometer for the ESO VLT.