Radio Linear and Circular Polarization from M81*

Abstract

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 Berkeley-Illinois-Maryland Association (BIMA) array to observe M81* at 86 and 230 GHz. M81* is unpolarized in the linear sense at a frequency as high as 86 GHz and shows variable circular polarization at a frequency as high as 15 GHz. The spectrum of the fractional circular polarization is inverted in most of our observations. The sign of circular polarization is constant over frequency and time. The absence of linear polarization sets a lower limit to the accretion rate of $10^{-7}{M}_{\odot }{y}^{-1}$. The polarization properties are strikingly similar to the properties of Sgr A*, the central radio source in the Milky Way. This supports the hypothesis that M81* is a scaled up version of Sgr A*. On the other hand, the broad band total intensity spectrum declines towards milimeter wavelengths which differs from previous observations of M81* and also from Sgr A*.

Astronomy & Astrophysics, minor changes, matching the published version, also available at http://www.mpifr-bonn.mpg.de/staff/abrunthaler/pub.shtml

References in corpus (20)

• The Supermassive Black Hole at the Galactic Center
• Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz
• A size of ~1 AU for the radio source Sgr A* at the centre of the Milky Way
• Interferometric Measurements of Variable 340 GHz Linear Polarization in Sagittarius A*
• Detection of the Intrinsic Size of Sagittarius A* through Closure Amplitude Imaging (includes Online Supporting Material)
• Constraining the Accretion Rate Onto Sagittarius A* Using Linear Polarization
• The Spectrum and Variability of Circular Polarization in Sagittarius A* from 1.4 to 15 GHz
• Circular Polarization of Radio Emission from Relativistic Jets
• Detection of Circular Polarization in the Galactic Center Black Hole Candidate Sagittarius A*
• A Stationary Core with a One-sided Jet in the Center of M81
• Variable Linear Polarization from Sagittarius A*: Evidence for a Hot Turbulent Accretion Flow
• Circular polarization from stochastic synchrotron sources
• The Linear Polarization of Sagittarius A* I. VLA Spectro-polarimetry at 4.8 and 8.4 GHz
• The Nuclear Jet in M81
• Scintillation-Induced Circular Polarization in Pulsars and Quasars
• The Location of the Core in M81
• Does circular polarisation reveal the rotation of quasar engines?
• The Linear Polarization of Sagittarius A* II. VLA and BIMA Polarimetry at 22, 43 and 86 GHz
• Detection of Circular Polarization in M81*
• A Radio Survey for Linear and Circular Polarization in Low Luminosity Active Galactic Nuclei

Cited by in corpus (13)

• 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*
• The Rotation Measure and 3.5mm Polarization of Sgr A*
• Evidence for A Parsec-scale Jet from The Galactic Center Black Hole: Interaction with Local Gas
• Discovery of a bright radio transient in M82: a new radio supernova?
• Unraveling circular polarimetric images of magnetically arrested accretion flows near event horizon of a black hole
• Revolutionizing Our Understanding of AGN Feedback and its Importance to Galaxy Evolution in the Era of the Next Generation Very Large Array
• The millimetre variability of M81* -- Multi-epoch dual frequency mm-observations of the nucleus of M81
• Radio jet precession in M81*
• Understanding the Geometry of Astrophysical Magnetic Fields
• VLBI imaging of M81* at 3.4 mm with source-frequency phase-referencing
• CHANG-ES XI: Circular Polarization in the Cores of Nearby Galaxies
• Diverse Polarimetric Features of AGN Jets from Various Viewing Angles: Towards a Unified View