The Discovery of Polarized Water Vapor Megamaser Emission in a Molecular Accretion Disk

TL;DR

This paper reports the first detection of polarized water vapor megamaser emission in an extragalactic molecular accretion disk, revealing magnetic field orientations and implications for disk stability and outflows.

Contribution

It presents the first observation of polarized water maser emission in an extragalactic source, providing insights into magnetic fields in accretion disks.

Findings

Magnetic fields are within 35 degrees of the sky plane.

Maser region may drive hydromagnetic outflows.

Revised central mass estimate is 16.6 million solar masses.

Abstract

For the first time in an extragalactic source, we detect linearly polarized water maser emission associated with the molecular accretion disk of NGC 1068. The position angles of the electric polarization vectors are perpendicular to the axes of filamentary structures in the molecular accretion disk. The inferred magnetic field threading the molecular disk must lie within approximately 35 degrees of the sky plane. The orientation of the magnetic fields relative to the disk plane implies that the maser region is unstable to hydromagnetically powered outflow; we speculate that the maser region may be the source of the larger scale molecular outflow found in ALMA studies. The new VLBI observations also reveal a compact radio continuum source, NGC 1068*, aligned with the near-systemic maser spots. The molecular accretion disk must be viewed nearly edge-on, and the revised central mass is (16.6 +/- 0.1) million solar masses.