Faraday tomography of LoTSS-DR2 data: II. Multi-tracer analysis in the high-latitude outer Galaxy

Abstract

We conducted a follow-up study on the analysis of the LOw Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS) mosaic in the high-latitude outer Galaxy presented in the first paper of this series. Here, we focus on the search for alignment between the magnetic field traced by dust, HI filaments, starlight optical linear polarisation, and linear depolarised structures (depolarisation canals) observed in low-frequency synchrotron polarisation. This alignment was previously found in several smaller fields observed with LOFAR, offering valuable insights into the nature of the interstellar medium and the 3D spatial distribution of the diffuse ionised medium. We aim to determine whether the alignment of the interstellar medium (ISM) phases observed through multiple tracers is a common occurrence or an exception. Additionally, in areas where depolarisation canals align with the magnetic field, we use starlight polarisation to constrain the distance to the structures associated with the observed canals. We employed the Rolling Hough Transform (RHT) and projected Rayleigh statistics (PRS) to identify and quantify the alignment between the different tracers. On the scale of the whole mosaic, we did not find any evidence of a universal alignment among the three tracers. However, in one particular area, the western region (Dec between $29^{\circ }$ and $70^{\circ }$ and RA between $7^{\mathrm{h}}44^{\mathrm{m}}$ and $9^{\mathrm{h}}20^{\mathrm{m}}$), we do find a significant alignment between the magnetic field, depolarisation canals, and HI filaments. Based on this alignment, we used the starlight polarisation of stars with known parallax distances to estimate that the minimum distance to the structures observed by LOFAR in this region lies within the range of 200 to 240 pc. We associate these structures with the edge of the Local Bubble.

arXiv comment11 pages, 10 figures; accepted for publication in A&A; data products are available at https://data.fulir.irb.hr/islandora/object/irb:367

References in corpus (30)

• LOFAR: The LOw-Frequency ARray
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Planck 2018 results. I. Overview and the cosmological legacy of Planck
• Faraday Rotation Measure Synthesis
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• The LOFAR Two-metre Sky Survey - II. First data release
• The LOFAR Two-metre Sky Survey -- V. Second data release
• 9286 Stars: An Agglomeration of Stellar Polarization Catalogs
• Radiative torques: Analytical Model and Basic Properties
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• A Parallax-based Distance Estimator for Spiral Arm Sources
• Magnetically Aligned HI Fibers and the Rolling Hough Transform
• The Effelsberg-Bonn HI Survey: Milky Way gas. First data release
• Updated Gaia-2MASS 3D maps of Galactic interstellar dust
• A Galactic-scale gas wave in the Solar Neighborhood
• Three-dimensional extinction maps: Inverting inter-calibrated extinction catalogues
• Mapping the Magnetic Interstellar Medium in Three Dimensions Over the Full Sky with Neutral Hydrogen
• Linear polarization structures in LOFAR observations of the interstellar medium in the 3C196 field
• Modeling the magnetized Local Bubble from dust data
• An application of an optimal statistic for characterising relative orientations
• The correct sense of Faraday rotation
• Diffuse polarized emission in the LOFAR Two-meter Sky Survey
• Intermediate- and high-velocity clouds in the Milky Way II: evidence for a Galactic fountain with collimated outflows and diffuse inflows
• A new probe of line-of-sight magnetic field tangling
• Canals beyond Mars: Beam depolarization in radio continuum maps of the warm ISM
• Magnetically aligned straight depolarisation canals and the rolling Hough transform
• Faraday tomography of LoTSS-DR2 data: I. Faraday moments in the high-latitude outer Galaxy and revealing Loop III in polarisation
• The multiphase and magnetized neutral hydrogen seen by LOFAR
• Canals in Milky Way radio polarization maps
• Faraday ghosts: depolarization canals in the Galactic radio emission

Cited by in corpus (5)

• An analytical model for the magnetic field in the thick shell of Galactic bubbles with uniform initial conditions
• Modeling Local Bubble analogs II: Synthetic Faraday rotation maps
• Magnetic Fields in the Shapley Supercluster Core with POSSUM: Challenging Model Predictions
• A three-dimensional reconstruction of the interstellar magnetic field toward a star-forming region
• Pulsar scintillation studies with LOFAR III. Annual variations in PSR~J0814$+$7429