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We conducted a Very Large Array survey of eleven low luminosity active galactic nuclei for linear and circular polarization at 8.4 GHz. We detected circular polarization in one source (M81*) and linear polarization in 3 sources. Sensitivity…

Astrophysics · Physics 2009-11-07 Geoffrey C. Bower , Heino Falcke , Richard R. Mellon

Synchrotron radiation from active galactic nuclei (AGN) is often highly polarized. We present a search for linear polarization with the Very Large Array (VLA) at 4.8 GHz and 8.4 GHz from the nearest AGN, Sagittarius A*. As a part of this…

Astrophysics · Physics 2009-10-31 Geoffrey C. Bower , Donald C. Backer , Jun-Hui Zhao , Miller Goss , Heino Falcke

We summarize the current state of polarization observations of Sagittarius A*, the compact radio source and supermassive black hole candidate in the Galactic Center. These observations are providing new tools for understanding accretion…

Astrophysics · Physics 2007-05-23 Geoffrey C. Bower

We report here the detection of circular polarization in the Galactic Center black hole candidate, Sagittarius A*. The detection was made at 4.8 GHz and 8.4 GHz with the Very Large Array. We find that the fractional circular polarization at…

Astrophysics · Physics 2009-10-31 Geoffrey C. Bower , Heino Falcke , Donald C. Backer

We measured the linear polarization of Sagittarius A* to be 7.2 +/- 0.6 % at 230 GHzusing the BIMA array with a resolution of 3.6 x 0.9 arcsec. This confirms the previously reported detection with the JCMT 14-m antenna. Our high resolution…

Astrophysics · Physics 2008-11-26 Geoffrey C. Bower , Melvyn C. H. Wright , Heino Falcke , Donald C. Backer

We present a search for linear polarization at 22 GHz, 43 GHz and 86 GHz from the nearest super massive black hole candidate, Sagittarius A*. We find upper limits to the linear polarization of 0.2%, 0.4% and 1%, respectively. These results…

Astrophysics · Physics 2009-10-31 Geoffrey C. Bower , Melvyn C. H. Wright , Donald C. Backer , Heino Falcke

We report on the submillimeter properties of Sagittarius A* derived from observations with the Submillimeter Array and its polarimeter. We find that the spectrum of Sgr A* between 230 and 690 GHz is slightly decreasing when measured…

Astrophysics · Physics 2009-11-11 Daniel P. Marrone , James M. Moran , Jun-Hui Zhao , Ramprasad Rao

Using the Submillimeter Array, we have made the first high angular resolution measurements of the linear polarization of Sagittarius A* at submillimeter wavelengths, and the first detection of intra-day variability in its linear…

Astrophysics · Physics 2009-11-13 D. P. Marrone , J. M. Moran , J. -H. Zhao , R. Rao

We present results from archival Very Large Array (VLA) data and new VLA observations to investigate the long term behavior of the circular polarization of M81*, the nuclear radio source in the nearby galaxy M81. We also used the…

Astrophysics · Physics 2009-11-11 Andreas Brunthaler , Geoffrey C. Bower , Heino Falcke

We report here BIMA array observations of linear polarization in Sagittarius A*, the compact radio source in the Galactic Center. These observations had a resolution of 20 arcsec x 5 arcsec oriented North-South. We do not detect linear or…

Astrophysics · Physics 2009-11-06 Geoffrey C. Bower , Melvyn C. H. Wright , Heino Falcke , Donald C. Backer

We report the first detections of circularly polarized emission at submillimeter wavelengths from the compact radio source and supermassive black hole candidate Sgr A* at a level of 1.2\pm0.3% at 1.3 mm wavelength (230 GHz) and 1.6\pm0.3%…

High Energy Astrophysical Phenomena · Physics 2015-05-28 Diego J. Muñoz , Daniel P. Marrone , James M. Moran , Ramprasad Rao

Millimeter polarimetry of Sgr A* probes the linearly polarized emission region on a scale of $\sim 10$ Schwarzschild radii ($R_S$) as well as the dense, magnetized accretion flow on scales out to the Bondi radius ($\sim 10^5 R_S$) through…

We report the detection of circular polarization in the compact radio jet of the nearby spiral galaxy M81 (M81*). The observations were made with the Very Large Array at 4.8 and 8.4 GHz and circular polarization was detected at both…

Astrophysics · Physics 2009-11-07 A. Brunthaler , G. C. Bower , H. Falcke , R. R. Mellon

We report the discovery of variability in the linear polarization from the Galactic Center black hole source, Sagittarius A*. New polarimetry obtained with the Berkeley-Illinois-Maryland Association array at a wavelength of 1.3 mm shows a…

Astrophysics · Physics 2009-11-10 Geoffrey C. Bower , Heino Falcke , Melvyn C. H. Wright , Donald C. Backer

Sagittarius A* is the source of near infrared, X-ray, radio, and (sub)millimeter emission associated with the supermassive black hole at the Galactic Center. In the submillimeter regime, Sgr A* exhibits time-variable linear polarization on…

Astrophysics of Galaxies · Physics 2014-11-20 Vincent L. Fish , Sheperd S. Doeleman , Avery E. Broderick , Abraham Loeb , Alan E. E. Rogers

Our aim is to characterize the polarized continuum emission properties including intensity, polarization position angle, and polarization percentage of Sgr A* at $\sim$100 (3.0 mm), $\sim$230 (1.3 mm), $\sim$345 (0.87 mm), $\sim$500 (0.6…

We report on 85-101 GHz light curves of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), observed in April 2017 with the Atacama Large Millimeter/submillimeter Array (ALMA). This study of high-cadence full-Stokes data…

High Energy Astrophysical Phenomena · Physics 2024-07-24 Maciek Wielgus , Sara Issaoun , Ivan Marti-Vidal , Razieh Emami , Monika Moscibrodzka , Christiaan D. Brinkerink , Ciriaco Goddi , Ed Fomalont

We report here multi-epoch, multi-frequency observations of the circular polarization in Sagittarius A*, the compact radio source in the Galactic Center. Data taken from the VLA archive indicate that the fractional circular polarization at…

Astrophysics · Physics 2009-11-07 Geoffrey C. Bower , Heino Falcke , Robert J. Sault , Donald C. Backer

Millimeter wavelength polarimetry of accreting black hole systems can provide a tomographic probe of the accretion flow on a wide range of linear scales. We searched for linear polarization in two low luminosity active galactic nuclei…

High Energy Astrophysical Phenomena · Physics 2017-12-08 Geoffrey C. Bower , Jason Dexter , Sera Markoff , Ramprasad Rao , R. L. Plambeck

We perform general relativistic ray-tracing calculations of the transfer of polarized synchrotron radiation through the relativistic accretion flow in Sagittarius (Sgr) A*. Based on a two-temperature magneto-rotational-instability (MRI)…

Astrophysics · Physics 2009-11-13 L. Huang , S. Liu , Z. -Q. Shen , M. J. Cai , H. Li , C. L. Fryer
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