Multi-tracer analysis of straight depolarisation canals in the surroundings of the 3C 196 field

Turić, Luka; Jelić, Vibor; Jaspers, Rutger; Haverkorn, Marijke; Bracco, Andrea; Erceg, Ana; Ceraj, Lana; van Eck, Cameron; Zaroubi, Saleem (2021) Multi-tracer analysis of straight depolarisation canals in the surroundings of the 3C 196 field. Astronomy & Astrophysics, 654 . ISSN 0004-6361

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Abstract

Context. 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 magnetised and multi-phase interstellar medium (ISM), such as dust and line emission from atomic hydrogen (HI). Aims: 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. Methods: We used 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 complemented the starlight polarisation with the corresponding distances. Results: Faraday tomography of the three fields shows a rich network of diffuse polarised emission at Faraday depths between − 10 and + 15 rad 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°). In one field, two groups of stars at distances below and above 200 pc, 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 in the magnetic field as probed by the stars, which corresponds to the edge of the Local Bubble.

Item Type:	Article
Uncontrolled Keywords:	ISM: general ; ISM: magnetic fields ; ISM: structure ; radio continuum ; ISM ; techniques ;interferometric ; techniques ; polarimetric
Subjects:	NATURAL SCIENCES > Physics NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Divisions:	Division of Experimental Physics
Projects:	Project title Project leader Project code Project type Razumijevanje zračenja na niskim radio frekvencijama: ususret novoj generaciji radio teleskopa Jelić, Vibor IP-2018-01-2889 HRZZ Origin of Magnetic strUctureS in the ISM obscuring the Cosmic DAwn Jelić, Vibor; Braco, Andrea 843008 EK
Depositing User:	Vibor Jelić
Date Deposited:	11 Nov 2021 06:53
URI:	http://fulir.irb.hr/id/eprint/6587
DOI:	10.1051/0004-6361/202141071

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