Variable Linear Polarization from Sagittarius A*: Evidence for a Hot Turbulent Accretion Flow

Abstract

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 position angle that differs by 28 +/- 5 degrees from observations 6 months prior and then remains stable for 15 months. This difference may be due to a change in the source emission region on a scale of 10 Schwarzschild radii or due to a change of 3 x 10^5 rad m^-2 in the rotation measure. We consider a change in the source physics unlikely, however, since we see no corresponding change in the total intensity or polarized intensity fraction. On the other hand, turbulence in the accretion region at a radius ~ 10 to 1000 R_s could readily account for the magnitude and time scale of the position angle change.

accepted for publication in ApJL

References in corpus (14)

• Three-dimensional MHD Simulations of Radiatively Inefficient Accretion Flows
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• Detection of the Intrinsic Size of Sagittarius A* through Closure Amplitude Imaging (includes Online Supporting Material)
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Cited by in corpus (63)

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• Resolved Magnetic-Field Structure and Variability Near the Event Horizon of Sagittarius A*
• Interferometric Measurements of Variable 340 GHz Linear Polarization in Sagittarius A*
• Sagittarius A* Accretion Flow and Black Hole Parameters from General Relativistic Dynamical and Polarized Radiative Modeling
• Observational appearance of inefficient accretion flows and jets in 3D GRMHD simulations: Application to Sgr~A*
• Towards the event horizon -- the supermassive black hole in the Galactic Center
• Coupled jet-disk model for Sgr A*: explaining the flat-spectrum radio core with GRMHD simulations of jets
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• Simultaneous Chandra, CSO and VLA Observations of Sgr A*: The Nature of Flaring Activity
• Polarimetric properties of Event Horizon Telescope targets from ALMA
• Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes
• How to hide large scale outflows: size constraints on the jets of Sgr A*
• Prospects for testing the nature of Sgr A*'s NIR flares on the basis of current VLT- and future VLTI-observations
• The Rotation Measure and 3.5mm Polarization of Sgr A*
• ALMA Polarimetry of Sgr A*: Probing the Accretion Flow from the Event Horizon to the Bondi Radius
• Simulations of imaging the event horizon of Sagittarius A* from space
• The Submillimeter Polarization of Sgr A*
• Jet-lag in Sgr A*: What size and timing measurements tell us about the central black hole in the Milky Way
• ALMA and VLA measurements of frequency-dependent time lags in Sagittarius A*: evidence for a relativistic outflow
• Star formation in accretion discs : from the Galactic Center to Active Galactic Nuclei
• Stochastic Acceleration in the Galactic Center HESS Source
• The Galactic Center Weather Forecast
• Modeling mm- to X-ray flare emission from SgrA*
• Spherical Accretion with Anisotropic Thermal Conduction
• The Circular Polarization of Sagittarius A* at Submillimeter Wavelengths
• Detecting Changing Polarization Structures in Sagittarius A* with High Frequency VLBI
• The pattern of accretion flow onto Sgr A*
• Faraday Conversion and Rotation In Uniformly Magnetized Relativistic Plasmas
• Self-consistent spectra from radiative GRMHD simulations of accretion onto Sgr A*
• Using Millimeter VLBI to Constrain RIAF Models of Sagittarius A*
• Testing the ALP-photon coupling with polarization measurements of Sagittarius A*
• Faraday Rotation in Global Accretion Disk Simulations: Implications for Sgr A*
• Cosmic Magnetism in Centimeter and Meter Wavelength Radio Astronomy
• The Variability of Polarized Radiation from Sgr A*
• Testing the Accretion Flow with Plasma Wave Heating Mechanism for Sagittarius a* by the 1.3MM Vlbi Measurements
• Linearly Polarized Millimeter and Submillimeter Continuum Emission of Sgr A* Constrained by ALMA
• Polarized Emission of Sagittarius A*
• Relative Astrometry of Compact Flaring Structures in Sgr A* with Polarimetric VLBI
• The 492 GHz emission of Sgr A* constrained by ALMA
• The millimetre variability of M81* -- Multi-epoch dual frequency mm-observations of the nucleus of M81
• Accretion of Low Angular Momentum Material onto Black Holes: Radiation Properties of Axisymmetric MHD Flows
• Linearly and Circularly Polarized Emission in Sagittarius A*
• Nonaxisymmetric Effects in the Black Hole Accretion Inviscid Hydrodynamics: Formation and Evolution of a Tilted Torus
• Spherically Symmetric Accretion Flows: Minimal Model with MHD Turbulence
• Radio Linear and Circular Polarization from M81*
• What is the Hidden Depolarization Mechanism in Low Luminosity AGN?
• On the role of strong gravity in polarization from scattering of light in relativistic flows
• Constraining Radiatively Inefficient Accretion Flows with Polarization
• Time Domain Filtering of Resolved Images of Sgr A*
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*
• Magnetically arrested disk flux eruption events to describe SgrA* flares
• Three-dimensional Radiative Properties of Hot Accretion Flows onto the Galactic Centre Black Hole
• Confronting the jet model of Sgr A* with the Faraday rotation measure observations
• Spherical Accretion in Nearby Weakly Active Galaxies
• Polarized signatures of adiabatically expanding hotspots in Sgr A*'s accretion flow
• X-ray observations of the hot phase in Sgr~A*
• Astrophysics in 2005
• An Observational Signature of Sub-Equipartition Magnetic Fields in the Spectra of Black Hole Binaries
• The Jet in the Galactic Center: An Ideal Laboratory for Magnetohydrodynamics and General Relativity
• Full-polarization millimeter wavelength variability of Sagittarius A* during the 2018 EHT campaign