Research on the Galactic Center is evolving rapidly. One of the main science drivers is the commissioning of new observatories, instruments, and/or techniques for observations and data reduction. Such examples are the introduction of adaptive optics for near-infrared imaging at the VLT and Keck telescopes, the start of the X-ray telescopes Chandra and XMM, or the beginning of operation of the High Energy Stereoscopic System (H.E.S.S.), an array of imaging atmospheric Cherenkov telescopes in Namibia.

The intention of this page is to highlight briefly some recent prominent results in GC research that were published after the editorial deadline. The compilation cannot be complete, but is thought rather as a guideline or  "appetizer". We would also like to refer the interested reader to the Galactic Center Newsletter - GCNEWS - that publishes new results on GC research in intervals of three to four months. Also, a compilation of refereed publications on the GC from the past year is provided here.

H.E.S.S.

The High Energy Stereoscopic System (H.E.S.S.) is an array of four 13m telescopes. They  operate in a stereoscopic coincidence mode and register the Cherenkov light that is produced by high energy photons in the atmophere. The enrgy threshold of the instrument is 100 GeV.  H.E.S.S. is located in the Khomas Highlands of Namibia. With its recent observations in 2003 and 2004, H.E.S.S. has provided the deepest and best resolved view so far of the Galactic Center region in Gamma-rays. A gamma-ray source, HESS J1745-290, was detected the position of which is compatible with Sgr A*. However, due to the complexity of the GC region, with its many potential high energy sources, HESS J1745-290 cannot yet be unambiguously identified with Sgr A*. Another possible candidate for the high energy emission is the supernova remnant Sgr A East. It is anticipated that the systematic error on the position of HESS J1745-290 can be reduced to ~10'' during 2005.

see: Aharonian, F.; Akhperjanian, A. G.; Aye, K.-M.; Bazer-Bachi, A. R.; Beilicke, M.; et al. (2004)

X-Ray Observations

An analysis of X-ray transients from 5 years of Chandra observations of the central 23 parsecs of the GC revealed an overabundance of these sources in the central 1 parsec. This overabundance of X-ray binaries agrees well with the long predicted accumulation of heavy stellar remnants in the bottom of the gravitational well near the supermassive black hole Sgr A*.

see: Muno et al. (2005)

Near-Infrared Observations

A real breakthrough could be achieved with the new adaptive optics integral-field spectrometer SINFONI at the ESO VLT. It allows to obtain diffraction limited images at the 8m class VLT of a FOV of about 1"×1" while at the same time providing spectra for each pixel in the image. Such an instrument is indispensable for obtaining spectra of stars in the crowded cusp around Sgr A*. First results show that the majority of stars within 1" of Sgr A* are ineed of early type, most probably B-type main sequence stars. The presence of these short-lived stars within a few mpc of the supermassive black hole presents one of the greatest enigmas in current Galactic Center research. In addition to identifying the nature of the stars, precise line-of-sight velocities could be determined as well, allowing to further constrain the orbits of stars around Sgr A* in combination with ongoing proper motion measurements. The most recent values for the black hole mass and the distance to Sgr A* derived from these measurements is 3.6±0.3 × 10^6 Msol and 7.6±0.3kpc.  Imaging spectroscopy allowed further to measure for the first time the spectral slope of NIR flares of Sgr A*.

see: Eisenhauer et al. (2005)