Exploring the making of a galactic wind in the starbursting dwarf irregular galaxy IC 10 with LOFAR
Journal article, 2018

Low-mass galaxies are subject to strong galactic outflows, in which cosmic rays may play an important role; they can be best traced with low-frequency radio continuum observations, which are less affected by spectral ageing. We present a study of the nearby starburst dwarf irregular galaxy IC 10 using observations at 140MHz with the Low-Frequency Array (LOFAR), at 1580MHz with the Very Large Array (VLA), and at 6200MHz with the VLA and the 100-m Effelsberg telescope.We find that IC 10 has a low-frequency radio halo, which manifests itself as a second component (thick disc) in the minor axis profiles of the non-thermal radio continuum emission at 140 and 1580 MHz. These profiles are then fitted with 1D cosmic ray transport models for pure diffusion and advection.We find that a diffusion model fits best, with a diffusion coefficient of D = (0.4-0.8) × 10 26 (E/GeV) 0.5 cm 2 s -1 , which is at least an order of magnitude smaller than estimates both from anisotropic diffusion and the diffusion length. In contrast, advection models, which cannot be ruled out due to the mild inclination, while providing poorer fits, result in advection speeds close to the escape velocity of ≈50 km s -1 , as expected for a cosmic ray-driven wind. Our favoured model with an accelerating wind provides a self-consistent solution, where the magnetic field is in energy equipartition with both the warm neutral and warm ionized medium with an important contribution from cosmic rays. Consequently, cosmic rays can play a vital role for the launching of galactic winds in the disc-halo interface.

Galaxies: magnetic fields

Radio continuum: galaxies

Cosmic rays


V. Heesen

University of Hamburg

D. Rafferty

University of Hamburg

A. Horneffer

Max Planck Society

R. Beck

Max Planck Society

A. Basu

Bielefeld University

Max Planck Society

J. Westcott

University of Hertfordshire

L. Hindson

University of Hertfordshire

E. Brinks

University of Hertfordshire

K. T. Chyy

Jagiellonian University in Kraków

A. M. M. Scaife

Jodrell Bank Centre for Astrophysics

M. Brueggen

University of Hamburg

G. Heald

University of Groningen

CSIRO Astronomy and Space Science

A. Fletcher

Newcastle University

Cathy Horellou

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

F. Tabatabaei

University of La Laguna

Instituto de Astrofísica de Canarias

R. Paladino

Istituto di Radioastronomia

B. Nikiel-Wroczýnski

University of Hertfordshire

Jagiellonian University in Kraków

M. Hoeft

Thüringer Landessternwarte Tautenburg

R. J. Dettmar

Ruhr-Universität Bochum

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 476 2 1756-1764

Subject Categories

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology

Ocean and River Engineering



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