GCNEWS
A Newsletter for Galactic Center Research
This Volume was edited by Angela Cotera, Heino Falcke & Sera Markoff
email: gcnews@aoc.nrao.edu
GCNEWS
We would like to thank all of our readers who participated in our online web poll, your input was greatly appreciated. The final tabulated results can be found in the Announcements, where you will also find the web address for the conference.
In addition to Tom Geballe (Gemini Observatory), your GCNEWS team (A. Cotera, S. Markoff, H. Falcke) will once again be Co-Chairs for the conference. On behalf of the Co-Chairs, I would like to express our appreciation for the members of our community who have agreed to serve on the SOC and who will decide on the final program of the conference:
Finally, we would like to acknowledge the numerous institutes whose generous contributions will help make this an outstanding conference: Gemini Observatory, The University of Hawaii Institute for Astrophysics, WM Keck Observatory, Subaru Telescope, and the Joint Astronomy Centre.
The scope of the conference will be the central 300 parsecs - the scale of the fantastic Chandra results presented in this issue of GCNEWS! The region to be covered by the conference is also well illustrated in the 90 cm image of the GC by Namir Kassim et al., which can be found at http://rsd-www.nrl.navy.mil/7213/lazio/GC.
The wealth of theoretical research and observational advances at X-ray, infrared, submillimeter and radio wavelengths, during the past 3 years will undoubtably contribute to an interesting conference and lively discussions. We are once again planning to reserve significant amounts of time for discussion of results, so you may expect more spirited debates. The time reserved for discussion, in conjunction with an allotment of 15-20 minutes per talk and the anticipated number of participants, means that the conference poster sessions will likely be a significant portion of the conference.
We are in the process of creating the registration webpages, and will let you know when they are in place. The information will be sent by email to our subscribers and the people who filled out the survey form.
Deadlines have not yet been firmly established, but look for an abstract deadline in late August, early September - approximately coincident with the hotel registration deadline. There will be an early
Now if we could just get Kilauea to erupt on November 9th....
The group announced the detection of over 1000 X-ray point sources which are both spatially and spectrally distinguished from diffuse X-ray emission. The point sources, thought to originate from accretion of material from a normal star onto a compact companion (white dwarf, neutron star, or black hole), have a spectral line at 6.7 KeV from highly ionized Fe. The diffuse X-ray emission peaking at the GC can now be explained by emission from hot gas with typical temperatures of 107 K, a factor of 10 cooler than previously thought due to the poor spatial resolution of prior datasets. The diffuse gas that exhibits the 6.4KeV Fe fluorescent line could be excited by cosmic rays from supernovae or might even be literally a ``reflection'' of an earlier time in our Galaxy's history when possibly much more radiation emanated from the supermassive black hole at Sgr A*.
During the press conference Cornelia Lang gave a memorable quote: ``The Galactic Center is dominated by very high pressures due to the hot gas component and the strong magnetic fields. It's a nice place to visit with a telescope, but I wouldn't want to live there.'' ( Remark: Not all of the editors would agree with the second half of that statement...)
F. Yusef-Zadeh presented evidence for interaction of a molecular cloud with the nonthermal radio filaments from the spectrum and morphology of X-ray emission. An X-ray filament is seen adjacent to a nonthermal radio filament and diffuse X-ray gas fills a shell that appears to be confined by the radio filaments. (C. Lang showed that only one of the magnetic nonthermal radio filaments has X-ray emission COINCIDENT with it.).
D. Chuss presented a thesis talk on the sub-mm polarization measurements of magnetic fields in the GC, showing the magnetic field to be toroidal (due to galactic rotation) at large spatial scales (5 arcmin resolution) but complex and correlated with radio and mid-IR structures at smaller spatial scales (20'' resolution).
J. H. Zhao presented a history of Sgr A*'s variability at 1.3 and 0.87 mm showed two strong flare events over 7 months. Monitoring of Sgr A*'s variability at 7mm, 1.3 cm and 2.0 cm was also presented in a poster (G. Bower et al). A 20% flare of three hours has been seen at 15 GHz - similar to the time scale of the big Chandra flare.
S. Stolovy presented improved 0.2'' NICMOS images of the ionized gas (as imaged in Paschen alpha) near Sgr A* after removing residual point source artifacts from bright Pa-alpha emission stars such as the IRS16 cluster. This revealed an ``arc'' of ionized gas near Sgr A*.
A. Cotera et al. presented subarcsecond resolution maps of the mid-IR dust temperature and opacity in the central parsec of the Galaxy from Keck. The temperature peaks at the embedded sources. Even more striking is a large gradient towards the central cluster.
R. McGary presented NH3 maps from the VLA of the inner 10 pc of the galaxy. These maps showed new elongated features that spatially and kinematically link giant molecular clouds to warmer molecular material closer to the GC.
S. Hyman reported a new radio transient source with no known counterpart 1.1 degrees north of the GC.
And finally...a little story involving the 2nd human to walk on the Moon... At one point late Wednesday afternoon, I was surprised to see Buzz Aldrin strolling by with some NASA administrators. When shown the beautiful color ``panorama'' Chandra image of the GC displayed in the poster area, Buzz asked where the black hole was, so I pointed it out to him and he went on his way....of course I assumed he meant the supermassive one at the very center-it's likely that there are many solar mass-black holes associated with the newly detected discrete X-ray sources.