Exploring the making of a galactic wind in the starbursting dwarf irregular galaxy IC 10 with LOFAR
Artikel i vetenskaplig tidskrift, 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.
Radio continuum: galaxies
Galaxies: magnetic fields
Cosmic rays
Författare
V. Heesen
Universität Hamburg
D. Rafferty
Universität Hamburg
A. Horneffer
Max-Planck-Gesellschaft
R. Beck
Max-Planck-Gesellschaft
A. Basu
Max-Planck-Gesellschaft
Universität Bielefeld
J. Westcott
University of Hertfordshire
L. Hindson
University of Hertfordshire
E. Brinks
University of Hertfordshire
K. T. Chyy
Uniwersytet Jagiellonski w Krakowie
A. M. M. Scaife
Jodrell Bank Centre for Astrophysics
M. Brueggen
Universität Hamburg
G. Heald
Rijksuniversiteit Groningen
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
A. Fletcher
Newcastle University
Cathy Horellou
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
F. Tabatabaei
Instituto de Astrofísica de Canarias
Universidad de la Laguna
R. Paladino
Istituto di Radioastronomia
B. Nikiel-Wroczýnski
University of Hertfordshire
Uniwersytet Jagiellonski w Krakowie
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 1756-1764Ämneskategorier
Meteorologi och atmosfärforskning
Astronomi, astrofysik och kosmologi
Havs- och vattendragsteknik
DOI
10.1093/mnras/sty325