Galaxy formation and evolution

Abstract:

We present preliminary results from spectroscopic observations of a sample of 11 low surface brightness galaxies (LSB). We measured the stellar and gaseous kinematics along their major and minor axes. Such information will allow us to accurately investigate the dark matter (DM) content within their optical regions, providing further constraints on the predictions of standard CDM models. Although dynamical modeling is still in progress, our observations already show that the derived stellar kinematics is more regular than the ionized gas one, which often shows evidence for non-circular and asymmetric motions.

Abstract:

A data reduction software package is developed to reduce data of the near-IR integral field spectrometer SPIFFI built at MPE. The basic data reduction routines are coded in ANSI C. The high level scripting language Python is used to connect the C-routines allowing fast prototyping. Several Python scripts are written to produce the needed calibration data and to generate the final result, a wavelength calibrated data cube with the instrumental signatures removed.

Abstract:

We present the results of a design study for the spectrograph module for KMOS - a cryogenic near-infrared multi-object spectrograph being developed as a second generation instrument for the VLT by a consortium of UK and German institutes. KMOS will consist of 24 deployable integral field units feeding three identical spectrograph units via image slicers. The spectrographs are designed to provide a resolving power greater than 3000, so as to provide adequate OH avoidance, whilst covering one of the J, H or K bands within a single exposure. We present the opto-mechanical layout of the spectrographs, together with an analysis of the impact of the image quality (and PSF uniformity) on the accuracy of sky background subtraction within each IFU's field of view.

Abstract:

In this and a companion paper (Eisenhauer et al. 2003b), we discuss some of the scientific results obtained during the SPIFFI guest instrument runs at the VLT in March and April 2003. This paper concentrates on results for the Galactic Center. Section I discusses the stellar population of the Galactic Center, in which we clearly detect, for the first time, an early, hot WN star, as well as a large number of WC stars. Analysis of the stellar population indicates that the young stars in the Galactic Center originated in a high metalicity starburst about 5 Myr ago. A surprising result is that essentially all young stars in the central 10" belong to one of two well defined, rotating stellar rings/disks. Section 2 outlines a new determination of the distance to the Galactic Center which is essentially free of systematic uncertainties in the astrophysical modelling, and gives R. as 7.94 +/- 0.42 kpc.