Letter to the Editor

The Local Bubble: a magnetic veil to our Galaxy

¹ Department of Astrophysics/IMAPP, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
e-mail: m.alves@astro.ru.nl
² Institut de Recherche en Astrophysique et Planétologie (IRAP), CNRS, Université de Toulouse, CNRS, 9 Avenue du Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
³ École normale supérieure/LERMA, Observatoire de Paris, Sorbonne Université, Université PSL, CNRS, Paris, France

Received: 13 January 2018
Accepted: 6 March 2018

Abstract

The magnetic field in the local interstellar medium does not follow the large-scale Galactic magnetic field. The local magnetic field has probably been distorted by the Local Bubble, a cavity of hot ionized gas extending all around the Sun and surrounded by a shell of cold neutral gas and dust. However, so far no conclusive association between the local magnetic field and the Local Bubble has been established. Here we develop an analytical model for the magnetic field in the shell of the Local Bubble, which we represent as an inclined spheroid, off-centred from the Sun. We fit the model to Planck dust polarized emission observations within 30^° of the Galactic poles. We find a solution that is consistent with a highly deformed magnetic field, with significantly different directions towards the north and south Galactic poles. This work sets a methodological framework for modelling the three-dimensional (3D) structure of the magnetic field in the local interstellar medium, which is a most awaited input for large-scale Galactic magnetic field models.