J/A+A/654/A5 Faraday cubes Fields A B and C (Turic+, 2021) ================================================================================ Multi-tracer analysis of straight depolarisation canals in the surroundings of the 3C 196 field. Turic L., Jelic V., Jaspers R., Haverkorn M., Bracco A., Erceg A., Ceraj L., van Eck C., Zaroubi S. =2021A&A...654A...5T (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Milky Way ; Polarization ; Radio continuum Keywords: ISM: general - ISM: magnetic fields - ISM: structure - radio continuum: ISM - techniques: interferometric - techniques: polarimetric Abstract: Faraday tomography of a field centred on the extragalactic point source 3C 196 with the LOw Frequency ARray (LOFAR) revealed an intertwined structure of diffuse polarised emission with straight depolarisation canals and tracers of the magnetized and multi-phase interstellar medium (ISM), such as dust and line emission from atomic hydrogen (HI). This study aims at extending the multi-tracer analysis of LOFAR data to three additional fields in the surroundings of the 3C 196 field. For the first time, we study the three-dimensional structure of the LOFAR emission by determining the distance to the depolarisation canals. We use the Rolling Hough Transform to compare the orientation of the depolarisation canals with that of the filamentary structure seen in HI and, based on starlight and dust polarisation data, with that of the plane-of-the-sky magnetic field. Stellar parallaxes from Gaia complement the starlight polarisation with the corresponding distances. Faraday tomography of the three fields shows a rich network of diffuse polarised emission at Faraday depths between -10rad/m^2^ and +15rad/m^2^. A complex system of straight depolarisation canals resembles that of the 3C 196 field. The depolarisation canals align both with the HI filaments and with the magnetic field probed by dust. The observed alignment suggests that an ordered magnetic field organises the multiphase ISM over a large area (~20{deg}). In one field, two groups of stars at distances below and above 200pc, respectively, show distinct magnetic-field orientations. These are both comparable with the orientations of the depolarisation canals in the same field. We conclude that the depolarisation canals likely trace the same change of the magnetic field as probed by the stars, which corresponds to the edge of the Local Bubble. Description: The Faraday depth cubes of three fields located nearby the 3C 196 field. Field A is located 10{deg} below the 3C 196 field, towards the Galactic plane; Field B is at similar Galactic latitude as the 3C 196 field, but 10{deg} towards larger Galactic longitudes; and Field C is in the coldest part of the North Galactic halo. The cubes are given in polarized intensity as a function of RA, Dec, and Faraday depth, synthesized from the LOw Frequency ARray (LOFAR) High Band Antennas (HBA) observations (Observational IDs: L428654, L431160 and L431596, taken under project code LC5_008). The cubes cover a Faraday depth range from -25rad/m^2^ to +25rad/m^2^ in 0.25rad/m^2^ steps, given in units of Jansky/PSF/RMSF. PSF is is Point Spread Function (3.9x3.6arcmin) and RMSF is Rotation Measure Spread Function (1.8rad/m^2^). The largest measured scale in Faraday depth is 0.8rad/m^2^. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file list.dat 71 3 List of fits datacubes fits/* . 3 Individual fits datacubes -------------------------------------------------------------------------------- Byte-by-byte Description of file: list.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.5 deg RAdeg Right ascension of image centre (J2000) 10- 18 F9.5 deg DEdeg Declination of image centre (J2000) 20- 23 I4 --- Nx Number of pixels in along X-axis 25- 28 I4 --- Ny Number of pixels in along Y-axis 30- 32 I3 --- Nz Number of pixels in Faraday depth 34- 40 I7 Kibyte size Size of FITS file 42- 50 A9 --- FileName Name of the fits file in subdirectory fits 52- 71 A20 --- Title Title of the fits file -------------------------------------------------------------------------------- Acknowledgements: Luka Turic, lturic(at)irb.hr ================================================================================ (End) Patricia Vannier [CDS] 25-Aug-2021