Signatures of young star formation activity within two parsecs of Sgr A*
- Department of Physics and Astronomy and CIERA, Northwestern University, Evanston, IL 60208 (United States)
- Department of Physics and Astronomy, and Research Center for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney NSW 2109 (Australia)
- Space Science Institute, 4750 Walnut St. Suite 205, Boulder, CO 80301 (United States)
- CRESST/UMBC/NASA GSFC, Code 665, Greenbelt, MD 20771 (United States)
- National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
- Department of Astronomy, University of Texas, Austin, TX 78712 (United States)
- Institut de Radio Astronomie Millimétrique, 300 rue de la Piscine, Dom. Univ., F-38406 St Martin d’Hères (France)
- Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
We present radio and infrared observations indicating ongoing star formation activity inside the ∼2–5 pc circumnuclear ring at the Galactic center. Collectively these measurements suggest a continued disk-based mode of ongoing star formation has taken place near Sgr A* over the last few million years. First, Very Large Array observations with spatial resolution 2.″17 × 0.″81 reveal 13 water masers, several of which have multiple velocity components. The presence of interstellar water masers suggests gas densities that are sufficient for self-gravity to overcome the tidal shear of the 4×10{sup 6} M{sub ⊙} black hole. Second, spectral energy distribution modeling of stellar sources indicates massive young stellar object (YSO) candidates interior to the molecular ring, supporting in situ star formation near Sgr A* and appear to show a distribution similar to that of the counter-rotating disks of ∼100 OB stars orbiting Sgr A*. Some YSO candidates (e.g., IRS 5) have bow shock structures, suggesting that they have gaseous disks that are phototoevaporated and photoionized by the strong radiation field. Third, we detect clumps of SiO (2-1) and (5-4) line emission in the ring based on Combined Array for Research in Millimeter-wave Astronomy and Sub-Millimeter Array observations. The FWHM and luminosity of the SiO emission is consistent with shocked protostellar outflows. Fourth, two linear ionized features with an extent of ∼0.8 pc show blue and redshifted velocities between +50 and −40 km s{sup −1}, suggesting protostellar jet driven outflows with mass-loss rates of ∼5×10{sup −5} M{sub ⊙} yr{sup −1}. Finally, we present the imprint of radio dark clouds at 44 GHz, representing a reservoir of molecular gas that feeds star formation activity close to Sgr A*.
- OSTI ID:
- 22882816
- Journal Information:
- Astrophysical Journal, Vol. 808, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ASTRONOMY
BLACK HOLES
COMPUTERIZED SIMULATION
COSMIC DUST
DISTRIBUTION
EMISSION
ENERGY SPECTRA
GALAXIES
GALAXY NUCLEI
GRAVITATION
LUMINOSITY
MASS TRANSFER
PHOTOIONIZATION
PROTOSTARS
RED SHIFT
SHOCK WAVES
SILICON OXIDES
SPATIAL RESOLUTION
STAR EVOLUTION
STELLAR WINDS