Polarised emission from aligned dust grains in nearby galaxies: predictions from the Auriga simulations

Abstract

(Aims) In this work, we predict the far-infrared polarisation signal emitted by non-spherical dust grains in nearby galaxies. We determine the angular resolution and sensitivity required to study the magnetic field configuration in these galaxies. (Methods) We post-process a set of Milky Way like galaxies from the Auriga project, assuming a dust mix consisting of spheroidal dust grains that are partially aligned with the model magnetic field. We constrain our dust model using Planck 353 GHz observations of the Milky Way. This model is then extrapolated to shorter wavelengths that cover the peak of interstellar dust emission and to observations of arbitrarily oriented nearby Milky Way like galaxies. (Results) Assuming an intrinsic linear polarisation fraction that does not vary significantly with wavelength for wavelengths longer than 50 micron, we predict a linear polarisation fraction with a maximum of $10-15\%$ and a median value of $\approx 7\%$ for face-on galaxies and $\approx 3\%$ for edge-on galaxies. The polarisation fraction anti-correlates with the line of sight density and with the angular dispersion function which expresses the large scale order of the magnetic field perpendicular to the line of sight. The maximum linear polarisation fraction agrees well with the intrinsic properties of the dust model. The true magnetic field orientation can be traced along low density lines of sight when it is coherent along the line of sight. These results also hold for nearby galaxies, where a coherent magnetic field structure is recovered over a range of different broad bands. (Conclusions) Polarised emission from non-spherical dust grains accurately traces the large scale structure of the galactic magnetic field in Milky Way like galaxies, with expected maximum linear polarisation fractions of $10-15\%$. To resolve this maximum, a spatial resolution of at least 1 kpc is required.

arXiv comment22 pages, 19 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (49)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Stellar population synthesis at the resolution of 2003
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• Theory of Star Formation
• The Interstellar Environment of our Galaxy
• SCUBA-2: The 10000 pixel bolometer camera on the James Clerk Maxwell Telescope
• Magnetic Fields in Spiral Galaxies
• Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust
• Efficient 3D NLTE dust radiative transfer with SKIRT
• SKIRT: an Advanced Dust Radiative Transfer Code with a User-Friendly Architecture
• The Millennium Arecibo 21-cm Absorption Line Survey. IV. Statistics of Magnetic Field, Column Density, and Turbulence
• Modelling the Pan-Spectral Energy Distribution of Starburst Galaxies: IV The Controlling Parameters of the Starburst SED
• Studies of regular and random magnetic fields in the ISM: statistics of polarization vectors and the Chandrasekhar-Fermi technique
• Optical colours and spectral indices of $z=0.1$ EAGLE galaxies with 3D dust radiative transfer code SKIRT
• Planck 2018 results. XII. Galactic astrophysics using polarized dust emission
• Planck intermediate results. XXII. Frequency dependence of thermal emission from Galactic dust in intensity and polarization
• Magnetic field formation in the Milky Way-like disk galaxies of the Auriga project
• The Herschel Exploitation of Local Galaxy Andromeda (HELGA) II: Dust and Gas in Andromeda
• Radiative transfer with POLARIS: I. Analysis of magnetic fields through synthetic dust continuum polarization measurements
• Vertical structure of a supernova-driven turbulent magnetized ISM
• Magnetic fields in cosmological simulations of disk galaxies
• The Balloon-borne Large Aperture Submillimeter Telescope: BLAST
• Far-infrared and dust properties of present-day galaxies in the EAGLE simulations
• SPICA - a large cryogenic infrared space telescope Unveiling the obscured Universe
• Moving Mesh Cosmology: Properties of Gas Disks
• Dust models compatible with Planck intensity and polarization data in translucent lines of sight
• The supernova-regulated ISM. II. The mean magnetic field
• Data release of UV to submm broadband fluxes for simulated galaxies from the EAGLE project
• The alignment of molecular cloud magnetic fields with the spiral arms in M33
• Faraday rotation maps of disk galaxies
• Polarization measurements analysis I. Impact of the full covariance matrix on polarization fraction and angle measurements
• JCMT BISTRO Survey observations of the Ophiuchus Molecular Cloud: Dust grain alignment properties inferred using a Ricean noise model
• ALMA Science Verification Data: Millimeter Continuum Polarimetry of the Bright Radio Quasar 3C 286
• The Origins Space Telescope
• The First Maps of ${\kappa }_d$ -- the Dust Mass Absorption Coefficient -- in Nearby Galaxies, with DustPedia
• The Failure of Monte Carlo Radiative Transfer at Medium to High Optical Depths
• The geometry of the magnetic field in the Central Molecular Zone measured by PILOT
• Composite biasing in Monte Carlo radiative transfer
• SOFIA Far Infrared Imaging Polarimetry of M82 and NGC 253: Exploring the Super-Galactic Wind
• Polarization in Monte Carlo radiative transfer and dust scattering polarization signatures of spiral galaxies
• High-resolution synthetic UV-submm images for simulated Milky Way-type galaxies from the Auriga project
• An Empirical Relation Between The Large-Scale Magnetic Field And The Dynamical Mass In Galaxies
• Probing the cold magnetized Universe with SPICA-POL (B-BOP)
• On the Shapes of Interstellar Grains: Modeling Extinction and Polarization by Spheroids and Continuous Distributions of Ellipsoids
• HAWC+ Far-Infrared Observations of the Magnetic Field Geometry in M51 and NGC 891
• The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry-BLASTPol: Performance and results from the 2012 Antarctic flight
• CosTuuM: polarized thermal dust emission by magnetically oriented spheroidal grains
• The supernova-regulated ISM. IV. A comparison of simulated polarization with Planck observations

Cited by in corpus (10)

• X-ray radiative transfer in full 3D with SKIRT
• UV to submillimetre luminosity functions of TNG50 galaxies
• Self-consistent dust and non-LTE line radiative transfer with SKIRT
• Monte Carlo radiative transfer with explicit absorption to simulate absorption, scattering, and stimulated emission
• The effect of cosmic variance on the characteristics of dust polarization power spectra
• Unveiling polarized emission from interstellar dust of the Large Magellanic Cloud with Planck
• TODDLERS: A New UV to Millimeter Emission Library for Star-Forming Regions. II. Star Formation Rate Indicators Using Auriga Zoom Simulations
• Far-infrared Polarization of the Supernova Remnant Cassiopeia A with SOFIA HAWC+
• Extragalactic magnetism with SOFIA (SALSA Legacy Program) -- IV: Program overview and first results on the polarization fraction
• Paradigmatic examples for testing models of optical light polarization by spheroidal dust