A Panoramic HST Infrared View of the Galactic Center Q. D. Wang, H. Dong, D. Calzetti (UMass), A. Cotera (SETI), S. Stolovy, M. Muno, J. Mauerhan, (Caltech/IPAC/JPL), C. C. Lang (U. of Iowa), M. R. Morris, E. A. Mills (UCLA), G. Schneider (U. Arizona) Please see also the posters by Hui (415.01) and Mills (416.10) et al. today. More information can be obtained at www.astro.umass.edu/~wqd/gcps/web/
HST/NICMOS 1.90µm Map of the Galactic Center l Foreground dusty clouds 15 (115 light-year) Arches cluster Quintuplet cluster Sgr A* b 39 (300 light-year) Distance to the Galactic center: 26,000 light-year Resolution: 0.025 light-year (0.2 ) 144 HST orbits, taken between Feb and June, 2008 144X4X4=2304 images for each of the two wavelength filters
HST/NICMOS 1.87µm Map of the Galactic Center Arched HII filaments Arches cluster Sickle HII region Quintuplet cluster Sgr A* The 1.9µm filter is sensitive to the stellar continuum emission. The 1.87µm filter covers the Pα line. Subtracting the 1.9µm map from the 1.87µm map adaptively. A net Pα line emission map (see the poster by Dong et al.; 415.01).
Net Pα Map of the Galactic Center Why do we need the HST? Excellent imaging stability Only observable from the space Little background due to the Earth s warm atmosphere
Map of Pα + stellar continuum: Preliminary Results Ionized gas features resolved into arrays of organized linear filaments strong local magnetic fields. ~0.6 million stars, resolving ~65% of the total stellar light observed. ~300 stars show enhanced Pα emission (green dots). ~2/3 of them are located outside the three known clusters. 13 have been followed up spectroscopically, confirming that they are indeed massive stars a new population of massive stars.
Sickle HII Region Detailed structure of ionized gas pillars sculpted by the intense radiation and wind from the Quintuplet cluster. But magnetic field may also play a critical role (see the poster by Mills et al.; 416.10). Red: radio continuum Green: Pα Blue: 1.9µm
Nuclear Spiral/Torus Sgr A* Ionized gas around the supermassive black hole is confined to a spiral embedded in a circumnuclear dusty torus. Evidence for ionized gas outflows from this torus. Red: 8µm (IRAC) Green: Pα Blue: 1.9µm
Detailed views of inidividual compact HII regions
Summery We have produced an unprecedented high-resolution infrared panorama of the Galactic center. Initial results: Discovery of a new population of very massive stars in relative isolation and with strong winds. Fine filamentary structures of ionized diffuse gas indicating profound influence of local strong magnetic field. Detections of compact nebulae, tracing various stages of massive star evolution We aim to understand the formation modes of massive stars and their interplay with the extreme environment in galactic nuclei. Please see posters by Dong (415.01) and Mills (416.10) et al. today More information available at www.astro.umass.edu/~wqd/gcps/web/ The research is supported by NASA/STScI
GC2009 Workshop: The window to nuclear environment of disk galaxies Place: Shanghai Dates: October 19-23 a 4.5 full-day science program, including min-debates focusing on key unsolved issues. A half-day tour (a small ancient town, the famous Bund, a banquet dinner on a boat touring the Huang-Pu river). http://www.shao.ac.cn/gc2009/
Topics physics of the accretion flow around SMBHs, including the mechanism of the flaring activity in Sgr A* high energy phenomena -- gamma rays and cosmic rays star formation in circumnuclear regions and the distinction from "normal" star formation environment stellar dynamics around SMBHs population and distribution of compact objects around SMBHs stellar and gaseous contents in the nuclear and circumnuclear regions and the fueling of SMBHs SMBH feedback effects on the nuclear and circumnuclear environment interplay between stars and the interstellar medium magnetic field and its role in regulating the gas dynamics fundamental physics at the Galactic Center (e.g., dark matter annihilation and GR effects) formation and evolution of SMBHs Q. Daniel Wang (Umass) wqd@astro.umass.edu)