The Submillimeter Polarization of Sgr A*

Abstract

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 simultaneously, indicating a transition to optically thin emission around 300-400 GHz. We also present very sensitive and well calibrated measurements of the polarization of Sgr A* at 230 and 345 GHz. With these data we are able to show for the first time that the polarization of Sgr A* varies on hour timescales, as has been observed for the total intensity. On one night we find variability that may arise from a polarized "blob" orbiting the black hole. Finally, we use the ensemble of observations to determine the rotation measure. This represents the first statistically significant rotation measure determination and the only one made without resorting to comparing position angles measured at separate epochs. We find a rotation measure of (-5.6+/-0.7)x10^5 rad/m^2, with no evidence for variability on inter-day timescales at the level of the measurement error. The stability constrains interday fluctuations in the accretion rate to 8%. The mean intrinsic polarization position angle is 167+/-7 degrees and we detect variations of 31+18/-9 degrees. This separation of intrinsic polarization changes and possible rotation measure fluctuations is now possible because of the frequency coverage and sensitivity of our data. The observable rotation measure restricts the accretion rate to the range 2x10^{-7} Msun/yr to 2x10^{-9} Msun/yr, if the magnetic field is near equipartition and ordered.

v2: Minor change to orbital calculation. Invited contribution to the proceedings of the Galactic Center Workshop 2006

References in corpus (32)

• Advection-Dominated Accretion: Underfed Black Holes and Neutron Stars
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
• Three-dimensional MHD Simulations of Radiatively Inefficient Accretion Flows
• The Supermassive Black Hole at the Galactic Center
• Convection-Dominated Accretion Flows
• The Dynamical Structure of Nonradiative Black Hole Accretion Flows
• Variable Infrared Emission from the Supermassive Black Hole at the Center of the Milky Way
• Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz
• Imaging Optically-Thin Hot Spots Near the Black Hole Horizon of Sgr A* at Radio and Near-Infrared Wavelengths
• Interferometric Measurements of Variable 340 GHz Linear Polarization in Sagittarius A*
• A deep submillimetre survey of the Galactic Centre
• Constraining the Accretion Rate Onto Sagittarius A* Using Linear Polarization
• The simultaneous spectrum of Sgr A* from 20cm to 1mm and the nature of the mm-excess
• A Multi-Wavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-ray, Soft $\gamma$-ray and Sub-millimeter Emission
• Frequency-Dependent Shift in the Image Centroid of the Black Hole at the Galactic Center as a Test of General Relativity
• Variability of Sagittarius A* - Flares at 1 Millimeter
• Sgr A* Polarization: No ADAF, Low Accretion Rate, and Non-Thermal Synchrotron Emission
• Circular Polarization of Radio Emission from Relativistic Jets
• Intra-day Variability of Sagittarius A* at 3 Millimeters
• Radiatively Inefficient Accretion Flow Models of Sgr A*
• Radio Variability of Sagittarius A* - A 106 Day Cycle
• Variable Linear Polarization from Sagittarius A*: Evidence for a Hot Turbulent Accretion Flow
• Circular polarization from stochastic synchrotron sources
• The Fate of Non-Radiative Magnetized Accretion Flows: Magnetically-Frustrated Convection
• The Linear Polarization of Sagittarius A* I. VLA Spectro-polarimetry at 4.8 and 8.4 GHz
• Intra-Day Variation of Sagittarius A* at Short Millimeter Wavelengths
• Simultaneous Multi-Wavelength Observations of Sgr A*
• The Linear Polarization of Sagittarius A* II. VLA and BIMA Polarimetry at 22, 43 and 86 GHz
• A Radio Transient 0.1 pc from Sagittarius A*
• The jet model for Sgr A*: radio and X-ray spectrum

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• Imaging a boson star at the Galactic center
• Simulating the Emission and Outflows from Accretion Disks
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• Testing the No-Hair Theorem with Observations in the Electromagnetic Spectrum. III. Quasi-Periodic Variability
• Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
• Millimeter Flares and VLBI Visibilities from Relativistic Simulations of Magnetized Accretion onto the Galactic Center Black Hole
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• Source-intrinsic near-infrared properties of Sgr A*: Total intensity measurements
• Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
• Modeling Seven Years of Event Horizon Telescope Observations with Radiatively Inefficient Accretion Flow Models
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• ALMA Polarimetry of Sgr A*: Probing the Accretion Flow from the Event Horizon to the Bondi Radius
• Global GRMHD Simulations of Black Hole Accretion Flows: a Convergence Study
• Numerical Parameter Survey of Nonradiative Black Hole Accretion -- Flow Structure and Variability of the Rotation Measure
• Dynamically important magnetic fields near the event horizon of Sgr A*
• Dynamical Imaging with Interferometry
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• MHD Simulations of Accretion onto Sgr A*: Quiescent Fluctuations, Outbursts, and Quasi-Periodicity
• The Circular Polarization of Sagittarius A* at Submillimeter Wavelengths
• Detecting Changing Polarization Structures in Sagittarius A* with High Frequency VLBI
• Magnetic reconnection plasmoid model for Sagittarius A* flares
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• The Atacama Cosmology Telescope: Microwave Intensity and Polarization Maps of the Galactic Center
• The Variability of Polarized Radiation from Sgr A*
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• Rapid Intrinsic Variability of Sgr A* at Radio Wavelengths
• Positron Effects on Polarized Images and Spectra from Jet and Accretion Flow Models of M87* and Sgr A*
• Bayesian techniques for comparing time-dependent GRMHD simulations to variable Event Horizon Telescope observations
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• A magnetized torus for modeling Sgr A* millimeter images and spectra
• Fitting the light curves of Sagittarius A* with a hot-spot model
• The 492 GHz emission of Sgr A* constrained by ALMA
• Far Infrared Variability of Sagittarius A*: 25.5 Hours of Monitoring with $Herschel$
• Bremsstrahlung in GRMHD models of accreting black holes
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• The Relationship Between Simulated Sub-Millimeter and Near-Infrared Images of Sagittarius A* from a Magnetically Arrested Black Hole Accretion Flow
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*
• Multi-wavelength torus-jet model for Sgr~A*
• Flare emission from Sagittarius A*
• Rotation Measure synthesis study and polarized properties of PSR J1745-2900 at 7 mm
• PATOKA: Simulating Electromagnetic Observables of Black Hole Accretion