The magnetic field of the Radcliffe wave: Starlight polarization at the nearest approach to the Sun

¹ Department of Space, Earth and Environment, Chalmers University of Technology, Gothenburg, Sweden
² Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
³ Institute for Astrophysical Research, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
⁴ Université Libre de Bruxelles, Science Faculty CP230, 1050 Brussels, Belgium
⁵ Istituto di Astrofisica e Planetologia Spaziali (IAPS), INAF, Via Fosso del Cavaliere 100, 00133 Roma, Italy
⁶ Department of Physics, Stanford University, Stanford, CA 94305, USA
⁷ Kavli Institute for Particle Astrophysics & Cosmology, Stanford University, PO Box 2450, Stanford, CA 94305, USA
⁸ University of Vienna, Department of Astrophysics, Türkenschanzstrasse 17, 1180 Vienna, Austria
⁹ Theoretische Physik IV, Fakultät für Physik & Astronomie, Ruhr-Universität Bochum, 44780 Bochum, Germany
¹⁰ Ruhr Astroparticle and Plasma Physics Center (RAPP Center), Ruhr-Universität Bochum, 44780 Bochum, Germany

^★ Corresponding author; georgia.panopoulou@chalmers.se

Received: 4 June 2024
Accepted: 5 December 2024

Abstract

Aims. We investigate the geometry of the magnetic field toward the Radcliffe wave, a coherent part of the nearby Local Arm of 3 kpc in length recently discovered via three-dimensional dust mapping.

Methods. We used archival stellar polarization in the optical and new measurements in the near-infrared to trace the magnetic field as projected on the plane of the sky. Our new observations cover the portion of the structure that is closest to the Sun, between Galactic longitudes of 122° and 188°.

Results. The polarization angles of stars immediately behind the Radcliffe wave appear to be aligned with the structure as projected on the plane of the sky. The observed magnetic field configuration is inclined with respect to the Galactic disk at an angle of 18°. This departure from a geometry parallel to the plane of the Galaxy is contrary to previous constraints from more distant stars and polarized dust emission. We confirm that the polarization angle of stars at larger distances shows a mean orientation parallel to the Galactic disk.

Conclusions. We discuss the implications of the observed morphology of the magnetic field for models of the large-scale Galactic magnetic field, as well as formation scenarios for the Radcliffe wave itself.