Alignment and Rotational Disruption of Dust Grains in the Galactic Centre Revealed by Polarized Dust Emission

Abstract

We study the alignment and rotational disruption of dust grains at the centre of our Galaxy using polarized thermal dust emission observed by SOFIA/HAWC+ and JCMT/SCUPOL at 53, 216, and 850 $\mu$m. We analyzed the relationship between the observed polarization degree with total emission intensity, dust temperature, gas column density, and polarization angle dispersion. Polarization degree from this region follows the predictions of the RAdiative Torque (RAT) alignment theory, except at high temperatures and long wavelengths where we found evidence for the rotational disruption of grains as predicted by the RAdiative Torque Disruption mechanism. The grain alignment and disruption sizes were found to be around 0.1 $\mu$m and 1 $\mu$m, respectively. The maximum polarization degree observed was around $p\sim 13$% at 216 $\mu$m and comes from a region of high dust temperature, low column density, and ordered magnetic field. Magnetically Enhanced RAT alignment (MRAT) was found to be important for grain alignment due to the presence of a strong magnetic field and can induce perfect alignment even when grains contain small iron clusters. We estimated the mass fraction of aligned grains using a parametric model for the fraction of the grains at high-$J$ attractors and found it to correlate weakly with the observed polarization degree. We observe a change in the polarization ratio, from $p_{216\mu m}/p_{850\mu m}<1$ to $p_{216\mu m}/p_{850\mu m}>1$ at $T_{\mathrm{d}}\gtrsim 35$ K, which suggests a change in the grain model from a composite to a separate population of carbon and silicate grains as implied by previous numerical modeling.

arXiv comment20 pages, 22 figures. Accepted for publication in MNRAS

References in corpus (69)

• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Infrared Emission from Interstellar Dust. IV. The Silicate-Graphite-PAH Model in the Post-Spitzer Era
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample
• Planck 2013 results. XI. All-sky model of thermal dust emission
• SCUBA: A common-user submillimetre camera operating on the James Clerk Maxwell Telescope
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Radiative torques: Analytical Model and Basic Properties
• The evolution of amorphous hydrocarbons in the ISM: dust modelling from a new vantage point
• Planck intermediate results. XIX. An overview of the polarized thermal emission from Galactic dust
• Tracing Magnetic Fields with Aligned Grains
• Radiative Torques on Interstellar Grains: II. Grain Alignment
• Inverse temperature dependence of the dust submillimeter spectral index
• Planck 2018 results. XII. Galactic astrophysics using polarized dust emission
• Radiative torque alignment: Essential Physical Processes
• Polarized Far-Infrared and Submillimeter Emission from Interstellar Dust
• Characterizing Precursors to Stellar Clusters with Herschel
• The Efficiency of Grain Alignment in Dense Interstellar Clouds: A Reassessment of Constraints from Near Infrared Polarization
• The Effect of Noise on the Dust Temperature - Spectral Index Correlation
• A unified model of grain alignment: radiative alignment of interstellar grains with magnetic inclusions
• Dynamics of Ionized Gas at the Galactic Center: VLA Observations of the 3D Velocity Field and Location of the Ionized Streams in Sagittarius A West
• The Herschel and JCMT Gould Belt Surveys: Constraining Dust Properties in the Perseus B1 Clump with PACS, SPIRE, and SCUBA-2
• Grain Alignment by Radiative Torques in Special Conditions and Implications
• Rotational Disruption of Dust Grains by Radiative Torques in Strong Radiation Fields
• Subsonic Mechanical Alignment of Irregular Grains
• Dust models compatible with Planck intensity and polarization data in translucent lines of sight
• Alignment of Irregular Grains by Mechanical Torques
• Submillimeter and Far-Infrared Polarimetric Observations of Magnetic Fields in Star-Forming Regions
• The Dust Emissivity Spectral Index in the Starless Core TMC-1C
• Spectropolarimetry of the 3.4 micron Feature in the Diffuse ISM toward the Galactic Center Quintuplet Cluster
• Planck intermediate results. XIV. Dust emission at millimetre wavelengths in the Galactic plane
• Alignment of Dust with Magnetic Inclusions: Radiative Torques and Superparamagnetic Barnett and Nuclear Relaxation
• The Excitation of HCN and HCO+ in the Galactic Center Circumnuclear Disk
• A dynamical constraint on interstellar dust models from radiative torque disruption
• Grain alignment and disruption by radiative torques in dense molecular clouds and implication for polarization holes
• JCMT BISTRO Survey observations of the Ophiuchus Molecular Cloud: Dust grain alignment properties inferred using a Ricean noise model
• The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333
• A $Herschel-SPIRE$ Survey of the Mon R2 Giant Molecular Cloud: Analysis of the Gas Column Density Probability Density Function
• The Galactic Centre in the Far Infrared
• Physical Model of Dust Polarization by Radiative Torque Alignment and Disruption and Implications for Grain Internal Structures
• Tensile Strength of Porous Dust Aggregates
• The far-infrared polarization spectrum of Rho Ophiuchi A from HAWC+/SOFIA observations
• On Internal and External Alignment of Dust Grains in Protostellar Environments
• 13CO Cores in Taurus Molecular Cloud
• ALMA View of the Circum-nuclear Disk of the Galactic Center; Tidally-disrupted Molecular Clouds falling to the Galactic Center
• Alignment and rotational disruption of dust
• Mid-Infrared Spectropolarimetric Constraints on the Core-Mantle Interstellar Dust Model
• Detection and characterization of a 500 mic dust emissivity excess in the Galactic Plane using Herschel/Hi-GAL observations
• A New Method to Trace Three-dimensional Magnetic Field Structure within Molecular Clouds Using Dust Polarization
• The Distribution of Mass Surface Densities in a High-Mass Protocluster
• A Magnetic Field Connecting the Galactic Center Circumnuclear Disk with Streamers and Mini-spiral -Implications from 850 $\mu$m Polarization Data
• Ionized Gas in the Galactic Center: New Observations and Interpretation
• Filament L1482 in the California molecular cloud
• Observations of magnetic fields surrounding LkH$\alpha$ 101 taken by the BISTRO survey with JCMT-POL-2
• Effects of grain alignment with magnetic fields on grain growth and the structure of dust aggregates
• Understanding polarized dust emission from $\rho$ Ophiuchi A in light of grain alignment and disruption by radiative torques
• Studying magnetic fields and dust in M17 using polarized thermal dust emission observed by SOFIA/HAWC+
• Physical Modeling of Dust Polarization from Magnetically Enhanced Radiative Torque (MRAT) Alignment in Protostellar Cores with POLARIS
• The Magnetic Field in the central parsec of the Galaxy
• SOFIA observations of 30 Doradus: I -- Far-Infrared dust polarization and implications for grain alignment and disruption by radiative torques
• Far-Infrared Polarization Spectrum of the OMC-1 Star-Forming Region
• Filamentary Star Formation: Observing the Evolution toward Flattened Envelopes
• The JCMT BISTRO Survey: Multi-wavelength polarimetry of bright regions in NGC 2071 in the far-infrared/submillimetre range, with POL-2 and HAWC+
• Observational evidence for rotational desorption of Complex Molecules by radiative torques from Orion BN/KL
• SOFIA Community Science I: HAWC+ Polarimetry of 30 Doradus
• Internal and external alignment of carbonaceous grains within the radiative torque paradigm

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