ALMA Observations of the Galactic Center: SiO Outflows and High-mass Star Formation near Sgr A*

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dc.contributor.authorYusef-Zadeh, F.
dc.contributor.authorRoyster, M.
dc.contributor.authorWardle, M.
dc.contributor.authorArendt, Richard
dc.contributor.authorBushouse, H.
dc.contributor.authorLis, D. C.
dc.contributor.authorPound, M. W.
dc.contributor.authorRoberts, D. A.
dc.contributor.authorWhitney, B.
dc.contributor.authorWootten, A.
dc.date.accessioned2022-06-09T16:23:38Z
dc.date.available2022-06-09T16:23:38Z
dc.date.issued2013-04-05
dc.description.abstractALMA observations of the Galactic center with a spatial resolution of 2farcs61 × 0farcs97 resulted in the detection of 11 SiO (5–4) clumps of molecular gas within 0.6 pc (15'') of Sgr A*, interior to the 2 pc circumnuclear molecular ring. The three SiO (5–4) clumps closest to Sgr A* show the largest central velocities, ∼150 km s−1, and the broadest asymmetric line widths with full width zero intensity (FWZI) ∼110–147 km s−1. The remaining clumps, distributed mainly to the NE of the ionized mini-spiral, have narrow FWZI (∼18–56 km s−1). Using CARMA SiO (2–1) data, Large Velocity Gradient modeling of the SiO line ratios for the broad velocity clumps constrains the column density N(SiO) ∼1014 cm−2, and the H2 gas density $n_{\rm H_2}=(3\hbox{--}9)\times 10^5$ cm−3 for an assumed kinetic temperature 100–200 K. The SiO clumps are interpreted as highly embedded protostellar outflows, signifying an early stage of massive star formation near Sgr A* in the last 104–105 yr. Support for this interpretation is provided by the SiO (5–4) line luminosities and velocity widths which lie in the range measured for protostellar outflows in star-forming regions in the Galaxy. Furthermore, spectral energy distribution modeling of stellar sources shows two young stellar object candidates near SiO clumps, supporting in situ star formation near Sgr A*. We discuss the nature of star formation where the gravitational potential of the black hole dominates. In particular, we suggest that external radiative pressure exerted on self-shielded molecular clouds enhances the gas density, before the gas cloud becomes gravitationally unstable near Sgr A*. Alternatively, collisions between clumps in the ring may trigger gravitational collapse.en_US
dc.description.sponsorshipWe thank Stefan Gillessen for providing us with VLT images. This work is partially supported by grants AST-0807400 from the NSF. This paper makes use of the following ALMA data: ADS/JAO.ALMA\#2011.0.0005.SVProject code. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with the NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ.en_US
dc.description.urihttps://iopscience.iop.org/article/10.1088/2041-8205/767/2/L32en_US
dc.format.extent7 pagesen_US
dc.genrejournal articlesen_US
dc.identifierdoi:10.13016/m2sysl-tjzj
dc.identifier.citationYusef-Zadeh, F., “ALMA Observations of the Galactic Center: SiO Outflows and High-mass Star Formation near Sgr A*”, The Astrophysical Journal Letters, vol. 767, no. 2, 2013. doi:10.1088/2041-8205/767/2/L32.en_US
dc.identifier.urihttps://doi.org/10.1088/2041-8205/767/2/L32
dc.identifier.urihttp://hdl.handle.net/11603/24873
dc.language.isoen_USen_US
dc.publisherIOP Scienceen_US
dc.relation.isAvailableAtThe University of Maryland, Baltimore County (UMBC)
dc.relation.ispartofUMBC Center for Space Sciences and Technology
dc.relation.ispartofUMBC Faculty Collection
dc.rightsThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.en_US
dc.titleALMA Observations of the Galactic Center: SiO Outflows and High-mass Star Formation near Sgr A*en_US
dc.typeTexten_US
dcterms.creatorhttps://orcid.org/0000-0001-8403-8548en_US

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