Extragalactic Magnetism with SOFIA (Legacy Program) - II: A Magnetically Driven Flow in the Starburst Ring of NGC 1097

Galactic bars are frequent in disk galaxies and they may support the transfer of matter toward the central engine of active nuclei. The barred galaxy NGC 1097 has magnetic forces controlling the gas flow at several kpc scales, which suggest that magnetic fields (B-fields) are dynamically important along the bar and nuclear ring. However, the effect of the B-field on the gas flows in the central kpc scale has not been characterized. Using thermal polarized emission at 89 μm with HAWC+/SOFIA, here, we measure that the polarized flux is spatially located at the contact regions of the outer bar with the starburst ring. The linear polarization decomposition analysis shows that the 89 μm and radio (3.5 and 6.2 cm) polarization traces two different modes, m, of the B-field: a constant B-field orientation and dominated by m = 0 at 89 μm, and a spiral B-field dominated by m = 2 at radio. We show that the B-field at 89 μm is concentrated in the warmest region of a shock driven by the galactic-bar dynamics in the contact regions between the outer bar with the starburst ring. Radio polarization traces a superposition of the spiral B-field outside and within the starburst ring. According to Faraday rotation measures between 3.5 and 6.2 cm, the radial component of the B-field along the contact regions points toward the galaxy's center on both sides. We conclude that gas streams outside and within the starburst ring follow the B-field, which feeds the black hole with matter from the host galaxy.

[1]  K. Subramanian,et al.  Extragalactic Magnetism with SOFIA (Legacy Program). I. The Magnetic Field in the Multiphase Interstellar Medium of M51 , 2021, The Astrophysical Journal.

[2]  J. Hill,et al.  The Origin of Parity Violation in Polarized Dust Emission and Implications for Cosmic Birefringence , 2021, The Astrophysical Journal.

[3]  R. Klessen,et al.  PHANGS–ALMA: Arcsecond CO(2–1) Imaging of Nearby Star-forming Galaxies , 2021, The Astrophysical Journal Supplement Series.

[4]  E. Lopez-Rodriguez The magnetic field across the molecular warped disk of Centaurus A , 2021, Nature Astronomy.

[5]  P. Diep,et al.  Grain Alignment and Disruption by Radiative Torques in Dense Molecular Clouds and Implication for Polarization Holes , 2020, 2010.07742.

[6]  Daniel C. M. Palumbo,et al.  Discriminating Accretion States via Rotational Symmetry in Simulated Polarimetric Images of M87 , 2020, The Astrophysical Journal.

[7]  Ed Elson,et al.  Synthesizing Observations and Theory to Understand Galactic Magnetic Fields: Progress and Challenges , 2019, Galaxies.

[8]  Zhi-Yun Li,et al.  Effects of grain alignment efficiency on synthetic dust polarization observations of molecular clouds. , 2019, Monthly notices of the Royal Astronomical Society.

[9]  G. Bruzual,et al.  From kpcs to the central parsec of NGC 1097: feeding star formation and a black hole at the same time , 2019, Monthly Notices of the Royal Astronomical Society.

[10]  Shaul Hanany,et al.  HAWC+/SOFIA Multiwavelength Polarimetric Observations of OMC-1 , 2018, The Astrophysical Journal.

[11]  R. Chary,et al.  The Highly Polarized Dusty Emission Core of Cygnus A , 2018, The Astrophysical Journal.

[12]  D. Benford,et al.  The Emission and Distribution of Dust of the Torus of NGC 1068 , 2018, The Astrophysical Journal.

[13]  R. B. Barreiro,et al.  Planck 2018 results , 2018, Astronomy & Astrophysics.

[14]  F. Tabatabaei,et al.  Discovery of massive star formation quenching by non-thermal effects in the centre of NGC 1097 , 2017, 1710.05695.

[15]  J. Binney,et al.  Gas flow in barred potentials , 2015, 1502.02740.

[16]  A. Lundgren,et al.  Multimolecule ALMA observations toward the Seyfert 1 galaxy NGC 1097 , 2014, 1410.2823.

[17]  G. W. Pratt,et al.  Planck intermediate results. XX. Comparison of polarized thermal emission from Galactic dust with simulations of MHD turbulence , 2014, 1405.0872.

[18]  G. Ven,et al.  Bar pattern speed and position of the circumnuclear ring in NGC 1097 , 2013, 1311.2953.

[19]  Prasanth H. Nair,et al.  Astropy: A community Python package for astronomy , 2013, 1307.6212.

[20]  T. Robitaille,et al.  APLpy: Astronomical Plotting Library in Python , 2012 .

[21]  D. Calzetti,et al.  Mapping the cold dust temperatures and masses of nearby KINGFISH galaxies with Herschel , 2012, 1207.1301.

[22]  David T. Chuss,et al.  HAWCPol: a first-generation far-infrared polarimeter for SOFIA , 2010, Astronomical Telescopes + Instrumentation.

[23]  B. Groves,et al.  Mapping far-IR emission from the central kiloparsec of NGC 1097 , 2010, 1005.1959.

[24]  A. Kovacs,et al.  Scanning strategies for imaging arrays , 2008, Astronomical Telescopes + Instrumentation.

[25]  David T. Chuss,et al.  Far-infrared polarimetry from the Stratospheric Observatory for Infrared Astronomy , 2007, SPIE Optical Engineering + Applications.

[26]  Claudia Winge,et al.  Streaming Motions toward the Supermassive Black Hole in NGC 1097 , 2006, astro-ph/0602002.

[27]  Bonn,et al.  Magnetic fields in barred galaxies - IV. NGC 1097 and NGC 1365 , 2005, astro-ph/0508485.

[28]  Witold Maciejewski,et al.  Feeding the Monster: The Nucleus of NGC 1097 at Subarcsecond Scales in the Infrared with the Very Large Telescope , 2005 .

[29]  Bonn,et al.  Magnetic fields in barred galaxies - I. The atlas , 2002, astro-ph/0207201.

[30]  D. Sokoloff,et al.  Magnetic field as a tracer of sheared gas flow in barred galaxies , 1999, Nature.

[31]  S. Faber,et al.  Homogeneous Velocity-Distance Data for Peculiar Velocity Analysis. III. The Mark III Catalog of Galaxy Peculiar Velocities , 1996, astro-ph/9610202.

[32]  D. Sokoloff,et al.  Galactic Magnetism: Recent developments and perspectives , 1996 .

[33]  P. Teuben,et al.  Nuclear Rings and Mass Inflow in Hydrodynamic Simulations of Barred Galaxies , 1995 .

[34]  D. Terndrup,et al.  Multiband Images of the Barred Galaxy NGC 1097 , 1995, astro-ph/9503067.

[35]  E. Athanassoula The existence and shapes of dust lanes in galactic bars , 1992 .

[36]  E. Athanassoula Morphology of bar orbits , 1992 .

[37]  Daniel C. M. Palumbo,et al.  First M87 Event Horizon Telescope Results. VII. Polarization of the Ring , 2021, The Astrophysical Journal Letters.

[38]  Daniel C. M. Palumbo,et al.  First M87 Event Horizon Telescope Results. VIII. Magnetic Field Structure near The Event Horizon , 2021, The Astrophysical Journal Letters.

[39]  N. Scoville,et al.  The Central Region of Barred Galaxies: Molecular Environment, Starbursts, and Secular Evolution , 2004, astro-ph/0402341.