AAS 205th Meeting, 9-13 January 2005
Session 32 The Galactic Center
Oral, Monday, January 10, 2005, 10:00-11:30am, Pacific 2/3

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[32.04] Interferometric detection of the polarization of Sgr A* at 340 GHz

D. P. Marrone, R. Rao, J. M. Moran (Harvard-Smithsonian CfA)

We report on high angular resolution (1-2 arcsec) interferometric measurements of the submillimeter polarization of Sgr A*. Using the Submillimeter Array, an interferometer located on Mauna Kea, Hawaii, we have measured a total flux of 2.6 Jy, with 6% linear polarization at a position angle of 170\degr. Similar polarization results were obtained in May and July, suggesting that we are observing a quiescent polarization state. Previous single dish measurements of the submillimeter polarization of Sgr A* were afflicted by polarized dust emission within the large JCMT beam (Aitken et al. ApJ 534, L173, 2000). These observations effectively eliminate this problem by reducing the beam solid angle by nearly two orders of magnitude, with the dust contamination reduced approximately proportionally. The measured polarization fraction is similar to that measured previously at 230 GHz with BIMA (Bower et al. ApJ, 588, 331, 2003), but much lower than the 13% measured by Aitken et al. The polarization fraction and position angle are consistent between our two sidebands, at 331.7 and 341.7 GHz. The difference in position angle between the two sidebands limits the rotation measure to 6\times 105 rad m-2. This rotation measure is too low for simple ADAF models that also match the Sgr A* spectral energy distribution, confirming the result of Bower et al.

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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.