Extragalactic Magnetism with SOFIA (Legacy Program). I. The Magnetic Field in the Multiphase Interstellar Medium of M51

The recent availability of high-resolution far-infrared (FIR) polarization observations of galaxies using HAWC+/SOFIA has facilitated studies of extragalactic magnetic fields in the cold and dense molecular disks. We investigate whether any significant structural differences are detectable in the kiloparsec-scale magnetic field of the grand design face-on spiral galaxy M51 when traced within the diffuse (radio) and the dense and cold (FIR) interstellar medium (ISM). Our analysis reveals a complex scenario where radio and FIR polarization observations do not necessarily trace the same magnetic field structure. We find that the magnetic field in the arms is wrapped tighter at 154 μm than at 3 and 6 cm; statistically significant lower values for the magnetic pitch angle are measured at FIR in the outskirts (R ≥ 7 kpc) of the galaxy. This difference is not detected in the interarm region. We find strong correlations of the polarization fraction and total intensity at FIR and radio with the gas column density and 12CO(1–0) velocity dispersion. We conclude that the arms show a relative increase of small-scale turbulent B-fields at regions with increasing column density and dispersion velocities of the molecular gas. No correlations are found with H i neutral gas. The star formation rate shows a clear correlation with the radio polarized intensity, which is not found in FIR, pointing to a small-scale dynamo-driven B-field amplification scenario. This work shows that multiwavelength polarization observations are key to disentangling the interlocked relation between star formation, magnetic fields, and gas kinematics in the multiphase ISM.

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

[2]  Jeff Reback,et al.  pandas-dev/pandas: Pandas 1.2.3 , 2021 .

[3]  E. Lopez-Rodriguez,et al.  The Strength and Structure of the Magnetic Field in the Galactic Outflow of Messier 82 , 2021, 2102.03362.

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

[5]  Edward J. Wollack,et al.  HAWC+ Far-infrared Observations of the Magnetic Field Geometry in M51 and NGC 891 , 2020, The Astronomical Journal.

[6]  F. G'omez,et al.  The effect of magnetic fields on properties of the circumgalactic medium , 2020, 2008.07537.

[7]  S. Reissl,et al.  Magnetized filamentary gas flows feeding the young embedded cluster in Serpens South , 2020, Nature Astronomy.

[8]  J. Devriendt,et al.  How primordial magnetic fields shrink galaxies , 2020, 2005.10269.

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

[10]  D. Lang,et al.  A z = 0 Multiwavelength Galaxy Synthesis. I. A WISE and GALEX Atlas of Local Galaxies , 2019, The Astrophysical Journal Supplement Series.

[11]  W. Schmidt,et al.  Global dynamics of the interstellar medium in magnetized disc galaxies , 2019, Monthly Notices of the Royal Astronomical Society.

[12]  Edward J. Wollack,et al.  SOFIA/HAWC+ Traces the Magnetic Fields in NGC 1068 , 2019, The Astrophysical Journal.

[13]  R. Walterbos,et al.  CHANG-ES , 2019, Astronomy & Astrophysics.

[14]  Shaul Hanany,et al.  SOFIA Far-infrared Imaging Polarimetry of M82 and NGC 253: Exploring the Supergalactic Wind , 2018, The Astrophysical Journal.

[15]  J. Rizzo,et al.  ALMA imaging of the nascent planetary nebula IRAS 15103–5754 , 2018, Monthly Notices of the Royal Astronomical Society.

[16]  A. Basu,et al.  The Magnetized Disk-Halo Transition Region of M51 , 2018, Proceedings of the International Astronomical Union.

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

[18]  Enzo Pascale,et al.  Relative Alignment between the Magnetic Field and Molecular Gas Structure in the Vela C Giant Molecular Cloud Using Low- and High-density Tracers , 2018, The Astrophysical Journal.

[19]  A. Bolatto,et al.  The EDGE-CALIFA Survey: Molecular and Ionized Gas Kinematics in Nearby Galaxies , 2018, The Astrophysical Journal.

[20]  Rene A. M. Walterbos,et al.  CHANG-ES IX: Radio scale heights and scale lengths of a consistent sample of 13 spiral galaxies seen edge-on and their correlations , 2017, 1712.03780.

[21]  R. Kennicutt,et al.  Accurate Distances to Important Spiral Galaxies: M63, M74, NGC 1291, NGC 4559, NGC 4625, and NGC 5398 , 2017, 1706.06586.

[22]  W. Jurusik,et al.  What drives galactic magnetism , 2017, 1705.07187.

[23]  C. B. Netterfield,et al.  The relation between the column density structures and the magnetic field orientation in the Vela C molecular complex , 2017, 1702.03853.

[24]  M. C. Eliche-Moral,et al.  Evolution of the anti-truncated stellar profiles of S0 galaxies since z=0.6 in the SHARDS survey , 2016, Proceedings of the International Astronomical Union.

[25]  R. Beck,et al.  Radio polarization and magnetic field structure in M 101 , 2016, 1601.06171.

[26]  Abhijit Bhausaheb Bendre,et al.  Dynamo saturation in direct simulations of the multi‐phase turbulent interstellar medium , 2015, 1510.04178.

[27]  R. Beck,et al.  Magnetic and gaseous spiral arms in M83 , 2015, 1510.00746.

[28]  John E. Vaillancourt,et al.  Interstellar Dust Grain Alignment , 2015 .

[29]  K. Subramanian,et al.  The origin, evolution and signatures of primordial magnetic fields , 2015, Reports on progress in physics. Physical Society.

[30]  R. Beck.  Magnetic fields in the nearby spiral galaxy IC 342: A multi-frequency radio polarization study , 2015, 1502.05439.

[31]  G. W. Pratt,et al.  Planck intermediate results. XXXV. Probing the role of the magnetic field in the formation of structure in molecular clouds , 2015, 1502.04123.

[32]  R. Beck,et al.  Do magnetic fields influence gas rotation in galaxies , 2014, 1407.6998.

[33]  A. Lazarian,et al.  Grain alignment by radiative torques in special conditions and implications , 2014, 1407.8228.

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

[35]  R. Beck,et al.  A new interpretation of the far-infrared – radio correlation and the expected breakdown at high redshift , 2013, 1306.6652.

[36]  Kraków,et al.  Large-scale radio continuum properties of 19 Virgo cluster galaxies. The influence of tidal interactions, ram pressure stripping, and accreting gas envelopes , 2013, 1304.1279.

[37]  A. Santillán,et al.  Magnetic fields: Impact on the rotation curve of the Galaxy , 2013, 1302.7253.

[38]  B. Groves,et al.  A detailed study of the radio-FIR correlation in NGC 6946 with Herschel-PACS/SPIRE from KINGFISH , 2013, 1301.6884.

[39]  A. Bolatto,et al.  The CO-to-H2 Conversion Factor , 2013, 1301.3498.

[40]  K. Alatalo,et al.  The ATLAS3D project - XIV. The extent and kinematics of the molecular gas in early-type galaxies , 2012, 1211.1011.

[41]  J. Pcekala,et al.  A possible influence of magnetic fields on the rotation of gas in NGC 253 , 2012, 1210.3082.

[42]  Megan C. Johnson,et al.  LITTLE THINGS , 2012, 1208.5834.

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

[44]  A. Shukurov,et al.  The supernova-regulated ISM - II. The mean magnetic field , 2012, 1206.6784.

[45]  D. Sokoloff,et al.  Current Status of Turbulent Dynamo Theory , 2012, 1203.6195.

[46]  P. Duc,et al.  Tides in colliding galaxies , 2011, 1112.1922.

[47]  J. Pcekala,et al.  The role of large-scale magnetic fields in galaxy NGC 891: can magnetic fields help to reduce the local mass-to-light ratio in the galactic outskirts? , 2011, 1111.6417.

[48]  K. Chyzy,et al.  Magnetic field evolution in interacting galaxies , 2011, 1107.3280.

[49]  Martin G. Cohen,et al.  THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE): MISSION DESCRIPTION AND INITIAL ON-ORBIT PERFORMANCE , 2010, 1008.0031.

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

[51]  C. Horellou,et al.  Magnetic fields and spiral arms in the galaxy M51 , 2010, 1001.5230.

[52]  Brenda C. Matthews,et al.  THE LEGACY OF SCUPOL: 850 μm IMAGING POLARIMETRY FROM 1997 TO 2005 , 2009 .

[53]  F. Özel,et al.  The relation between optical extinction and hydrogen column density in the Galaxy , 2009 .

[54]  Marita Krause,et al.  Evolution of magnetic fields in galaxies and future observational tests with the Square Kilometre Array , 2008, 0810.3114.

[55]  E. Brinks,et al.  THINGS: THE H i NEARBY GALAXY SURVEY , 2008, 0810.2125.

[56]  D. Tsiklauri.  Galaxy rotation curves: the effect of $\vec{j} \times\vec{B}$ force , 2008, 0806.1513.

[57]  U. Ziegler,et al.  Direct simulations of a supernova-driven galactic dynamo , 2008, 0805.2616.

[58]  J. Brown,et al.  The Outer Scale of Turbulence in the Magnetoionized Galactic Interstellar Medium , 2008, 0802.2740.

[59]  U. Ziegler,et al.  Dynamo coefficients from local simulations of the turbulent ISM , 2008, 0801.4004.

[60]  Daniel J. Price,et al.  Magnetic fields and the dynamics of spiral galaxies , 2007, 0710.3558.

[61]  Marija Strojnik-Scholl,et al.  Infrared Spaceborne Remote Sensing and Instrumentation XV , 2007 .

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

[63]  A. Lazarian,et al.  Radiative torques: analytical model and basic properties , 2007, 0707.0886.

[64]  C. Horellou,et al.  Analysis of spiral arms using anisotropic wavelets: gas, dust and magnetic fields in M51 , 2006, astro-ph/0609787.

[65]  Walter A. Siegmund,et al.  # 2006. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE 2.5 m TELESCOPE OF THE SLOAN DIGITAL SKY SURVEY , 2005 .

[66]  E. Florido.  Are rotation curves in NGC 6946 and the Milky Way magnetically supported , 2005, astro-ph/0503657.

[67]  D. Iono,et al.  Atomic and Molecular Gas in Colliding Galaxy Systems. I. The Data , 2005, astro-ph/0501588.

[68]  A. Szalay,et al.  The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission , 2004, astro-ph/0411302.

[69]  K. Subramanian,et al.  Astrophysical magnetic fields and nonlinear dynamo theory , 2004, astro-ph/0405052.

[70]  Germany,et al.  Scaling and correlation analysis of galactic images , 2001, astro-ph/0109017.

[71]  T. Jones.  The Magnetic Field Geometry in M82 and Centaurus A , 2000, astro-ph/0009122.

[72]  T. Jenness,et al.  Magnetic field surrounding the starburst nucleus of the galaxy M82 from polarized dust emission , 2000, Nature.

[73]  E. Zweibel,et al.  Generation of the Primordial Magnetic Fields during Cosmological Reionization , 2000, astro-ph/0001066.

[74]  D. Sokoloff,et al.  Depolarization and Faraday effects in galaxies , 1998 .

[75]  T. Jones.  Infrared imaging polarimetry of galaxies , 1997 .

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

[77]  R. Beck,et al.  Magnetic fields in spiral galaxies , 1990, 1509.04522.

[78]  M. Stephens,et al.  K-Sample Anderson–Darling Tests , 1987 .

[79]  W. W. Shane,et al.  Polarisation detection at radio wavelengths in three spiral galaxies , 1976, Nature.

[80]  J. Wardle,et al.  The linear polarization of quasi-stellar radio sources at 3.71 and 11.1 centimeters. , 1974 .

[81]  J. H. Piddington.  THE MAGNETIC FIELDS AND RADIO EMISSION OF GALAXIES , 1964 .

[82]  L. Aller.  Magnetic stellar envelopes and planetary nebulae. , 1958 .

[83]  OUP accepted manuscript , 2020, Monthly Notices of the Royal Astronomical Society.

[84]  D. Ward-Thompson,et al.  Evidence for a spiral magnetic field configuration in the galaxy M51 , 1987 .

[85]  Samuel B. Williams,et al.  ASSOCIATION FOR COMPUTING MACHINERY , 2000 .