The possibility of an IAU working group for the Galactic Center is also still in the works. Joseph has been in contact with Patricia Whitelock, president of the IAU Division VII: The Galactic System, regarding the possibility of bringing GCNews into the IAU. She has suggested that we form a working group focussed on low-luminosity galactic centers. Under the aegis of such a working group would be not only Sgr A* and its environs, but also M31*, M81*, and other such nearby objects. We welcome input on this possibility. Does it seem useful to form such a working group and try to explore the potential connections between nearby low-luminosity nuclei? Alternately, would such a working group, with its larger focus, dilute the impact of new discoveries in the Milky Way's Galactic center? We welcome your input and, if you favor the establishment of a working group, suggestions for a name.
If you have not already noticed, we have an extremely jam-packed GCNEWs this time around! Since our last issue, where we included the Ghez et al. abstract about Sgr A*'s dramatic identification in the infrared (IR), Genzel et al. reported their new results in Nature. The detections from both groups have dominated Galactic Center discussions ever since, and are generating a level of excitement on par with Chandra's X-ray discoveries a few years ago. Finally, there is a solid constraint on the ``submm bump'' emission in the IR, and now that they know where to look for it, we can expect simultaneous observations to really nail down Sgr A*'s quiescent and flaring broadband behavior. We are extremely pleased to be able to bring you summaries of these new results with back-to-back articles from both observing groups. Sgr A* has turned out to be as active in the IR as the X-rays, and the preliminary data show signs of a much shorter periodicity than the 106 day cycle seen in the radio (e.g. Zhao, Bower & Goss 2001, ApJ, 547, 29L). In addition to the articles here, the web addition has enhanced images and movies of some of the results, so please be sure to take a look at the online version.
In the Abstracts section, we also have an article by Zhao et al. reporting on a possible correlated radio/X-ray event, and a new detection of Sgr A* at low frequencies by Nord et al. Several groups have also reported new molecular and dust studies of the GC region, as well as one theoretical model paper suggesting we may be seeing signs of old Gamma-ray Bursts in our Galaxy via ultra-high energy cosmic rays!
Sgr A* has been getting a lot of press lately, especially because of the new results showcased in the next sections. In the following we summarize some of the GC-related results presented at conferences recently.
Sera had the pleasure of attending a small ``Micro-Workshop on Sgr A*'' at the Radcliffe Institute for Advanced Study last November. The meeting was an advanced seminar on the "Formation and Evolution of Stars Near the Galactic Center'', organized by Andrea Ghez, Alyssa Goodman, Josh Grindlay and Ramesh Narayan, and which featured three days of in-depth discussion. Along with the organizers, speakers included Mark Reid, Mark Morris, Fred Adams, Volker Bromm, Frank Shu, Lee Hartmann, Tal Alexander, Jeremy Goodman, Brad Hansen, Milos Milosavljevic and Eve Ostriker. Eve did the conference summary talk, which is currently posted online in both slide and pdf format at: http://cfa-www.harvard.edu/~agoodman/Presentations/Galactic_Center_03/, and Radcliffe may be posting the rest of the talks so stay tuned.
The Micro-Workshop was chaired by Jim Moran, and contained both observational and theoretical talks about IR and submm variability in Sgr A*, and possible interpretations. The speakers included Ramesh Narayan, Fred Baganoff, Reinhard Genzel, Andrea Ghez, Jun-Hui Zhao, Feng Yuan and Sera. The IR results presented are the same as what we have in this volume, and please see the abstract by Zhao et al. for the radio flare.
There was also a strong GC presence at the winter AAS meeting in Atlanta (January 4-8). Some of these presentations built upon work described at the GC Workshop in Kona last year, while other presentations contained new material. We describe briefly those papers with a GC component at the AAS meeting, with apologies to anybody whose work we might have missed. We give the AAS paper number in parentheses at the end of each summary.
Papers can be grouped generally into a small number of topics. There were a number of studies of the interstellar medium in the GC.
There is also a growing recognition of the importance of massive stars in the GC:
The Chandra X-ray Observatory continues to be an important tool in observing the GC:
Of course Sgr A* continues to command attention as the closest example of a nearby supermassive black hole: