VLT and APEX team up to study flares from the black hole at the Milky Way's core

Cologne astronomers led the effort to use two different telescopes simultaneously to study the violent flares from the supermassive black hole in the centre of the Milky Way. They have detected outbursts from this region, known as Sagittarius A*, which reveal material being stretched out as it orbits in the intense gravity close to the central black hole.

The team of European and US astronomers used ESO's Very Large Telescope (VLT) and the Atacama Pathfinder Experiment (APEX) telescope, both in Chile, to study light from Sagittarius A* at near-infrared wavelengths and the longer submillimetre wavelengths respectively. This is the first time that astronomers have caught a flare with these telescopes simultaneously. The telescopes' location in the southern hemisphere provides the best vantage point for studying the Galactic Centre.

"Observations like this, over a range of wavelengths, are really the only way to understand what's going on close to the black hole," says Andreas Eckart of the University of Cologne, who led the team.

ESO Press Release 41/08 - 18 November 2008 (cst)

At the heart of the Milky Way lies a supermassive black hole, called 'Sagittarius A*'. It contains 3.7 million times as much mass as our Sun. A few times per day, Sagittarius A* shows sudden bursts of radiation - termed 'flares' - that can be detected with X-ray observatories (like the American satellite 'Chandra' or the European 'XMM' observatory) and with radio and optical telescopes. These flares are related to the black hole guzzling gas and dust from its environment. However, the exact cause of the flares remains enigmatic. Astrophysicists believe that they can learn a great deal about black holes and Einstein's theory of relativity from a study of these phenomena. In order to understand the flares of Sagittarius A* it is necessary to examine their behavior in as many regions of the electromagnetic spectrum as possible, from X-rays to radio waves. The effort for preparing such experiments is very high because observing time has to be proposed for at many observatories across the world. Additionally, all these observations have to take place at the same time. The astrophysicists of the group around Prof. Andreas Eckart from the University of Cologne, in collaboration with scientists from the USA, have been successful in setting up such a campaign. In May they will observe the black hole for 10 days with telescopes around the world. Participating observatories are the Very Large Telescope of the European Southern Observatory (ESO) and the Gemini South telescope in Chile, the radio telescope in Effelsberg, Germany, the Plateau de Bure Interferometer in France, the IRAM30m telescope on the Pico Veleta near Granada in Spain, the new CARMA radio interferometer and the Very Long Baseline Array (VLBA) in the USA, and the ATCAradio interfermeter in Australia. By combining radio telescopes across three continents, it will be possible to observe the black hole for 24 hours a day. Scientists from the University of Cologne will be present at all these telescopes in the time from 14 to 24 May 2007. Galactic Center science at the I. Physikalisches Institut of the University of Cologne

(May 7, 2007, rs)

Since August 2006 Andreas Eckart is external member of the Max-Planck-Institute for Radioastronomy (MPIfR) in Bonn and scientific member of the Max-Planck society.

This nomination tightens the collaborative bonds between the I. Physikalisches Institut and the MPIfR.

Main common research activities that are strengthened through this new development are
interferometry efforts from the radio to the infrared and the detailed investigation of the interstellar medium especially in external galaxies.

(October, 16, 2006, jz)

Dr. Rainer Schödel Otto-Hahn-Medal winner 2005

Dr. Rainer Schödel

Scientist at the I. Physikalisches Institut wins the Otto-Hahn-Medal 2005 for his work (PhD-thesis) on the Galactic Centre.

Congratulations !

(July 21, 2005)

Die variable Quelle Sagittarius A* im Zentrum unserer Milchstraße bietet die einzigartige Möglichkeit, die Prozesse in unmittelbarer Nähe eines Schwarzen Loches zu untersuchen. Dieses Projekt ist der Analyse von Nahinfrarot-Beobachtungen mit dem Very Large Telescope (VLT, Chile) gewidmet. Es wird die Einarbeitung in die grundsätzlichen Prozeduren der Datenreduktion und der Zeitreihenanalyse umfassen, wie auch die Beschäftigung mit teilweise unbearbeiteten Daten der aktuellen Beobachtungsläufe von 2007 und 2008 und den aktuellen Publikationen.

(Betreuer: G. Witzel)

Das Verstehen der bei der Verschmelzung von Galaxien beteiligten Prozesse ist eine wichtige Zutat für Modelle, die die Evolution von Galaxien und supermassiven schwarzen Löchern zu beschreiben versuchen. Obwohl rechenintensiv, lässt sich mit Hilfe von vorgefertigten Bibliotheken – die zum Teil über das Virtuelle Observatorium abrufbar sind – ein beachtlich guter Fit an die Beobachtungen finden. Dies soll mit dem Software-Paket 'Identikit' an realen Beobachtungsdaten (von 8m Klasse Teleskopen) getestet werden.

(Betreuer: J. Zuther)

Betreuer: Prof. Andreas Eckart, Raum 205, 470-3546

O/B type stars evolve within less than 100,000 years toward the main sequence and disperse their natal cloud by their intense radiation and winds. Therefore, observations of such massive stars in their earliest phases are extremely rare. The southern HII region G333.6-0.2 is an extremely young, embedded site of massive star formation. Adaptive optics imaging observations of G333.6-0.2 with NACO at the ESO VLT show it contains at least a dozen early B/late O stars. The KLF of the cluster appears flat at the bright end. The existing near infrared multi-wavelength imaging data on this object should be analysed in the framework of a diploma thesis. The structure of the cluster, its luminosity function and the colors of the young stars should be derived. Are there indications for mass segregation? Are there massive stars with infrared excess that indicates that they are still surrounded by some of the material from which they were born? The cluster should be compared with other young clusters. Follow-up observations may become available or can be applied for with the results of the analysis.

Betreuer: Prof. Andreas Eckart, Raum 205, 470-3546

Imaging observations of the Galactic Center at a wavelength of 10 mum were obtained by our group in June 2006. We offer a diploma thesis on the analysis of the available data. What are the properties of the detectable point sources? What are the characteristics of the diffuse emission and of the visible shock fronts? Can variability of point sources or of extended sources be detected by combining the available data with older images? What do we learn from the mid-infrared emission in the circum-nuclear disk, the ring of dense molecular gas that surrounds the ~3 pc diameter central cavity?