Cosmic-ray electron propagation in NGC 3044 from radio continuum observations

Abstract

Star-forming edge-on galaxies often exhibit extended halo radiation in multiple bands, providing ideal laboratories for studying the transfer of matter from the disk to the halo. We investigate the transport of cosmic-ray electrons (CREs) and the associated galactic wind, and assess their impact on the surrounding medium in NGC 3044. We obtained the NGC 3044 total intensity image at 943 MHz from the Australian SKA Pathfinder (ASKAP) observations with a resolution of 16 arcsec and an rms noise of 20 $\mu$Jy beam${}^{-1}$. The sensitivity is higher than the previous observations at similar frequencies. We find that the ASKAP intensity profiles perpendicular to the disk can be fit with two exponential components. The scale heights of the thin and thick disks are $0.43\pm 0.13$ kpc and $1.91\pm 0.26$ kpc, respectively. By jointly fitting total intensity and spectral index profiles with one-dimensional advection and diffusion models, we find that CREs are advected outward from the disk with the velocity increasing with height in a power law. Beyond $\sim 3$ kpc, the velocity exceeds the escape speed of $\sim 400$ km s${}^{-1}$, indicating a strong wind. We further identify a possible superbubble of radius $\sim 3$ kpc filled with soft X-ray emitting hot gas and surrounded by an HI shell and a bright H$\alpha$ rim. These results demonstrate that radio continuum observations provide a powerful probe of cosmic-ray-driven winds in normal star-forming spiral galaxies.

References in corpus (24)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• CASA, the Common Astronomy Software Applications for Radio Astronomy
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey I: A low-frequency extragalactic catalogue
• Revised equipartition & minimum energy formula for magnetic field strength estimates from radio synchrotron observations
• An optimized algorithm for multi-scale wideband deconvolution of radio astronomical images
• The Rapid ASKAP Continuum Survey I: Design and First Results
• The Rapid ASKAP Continuum Survey Paper II: First Stokes I Source Catalogue Data Release
• Radio haloes in nearby galaxies modelled with 1D cosmic-ray transport using SPINNAKER
• CHANG-ES XXII: Coherent Magnetic Fields in the Halos of Spiral Galaxies
• LOFAR reveals the giant: a low-frequency radio continuum study of the outflow in the nearby FR I radio galaxy 3C 31
• Efficient wide-field radio interferometry response
• CHANG-ES XIII: Transport processes and the magnetic fields of NGC 4666 - indication of a reversing disk magnetic field
• The NOD3 software package: A graphical user interface-supported reduction package for single-dish radio continuum and polarisation observations
• CHANG-ES XX. High Resolution Radio Continuum Images of Edge-on Galaxies and their AGNs -- Data Release 3
• CHANG-ES XXIII: Influence of a galactic wind in NGC 5775
• The radio continuum perspective on cosmic-ray transport in external galaxies
• CHANG-ES XXVI: Insights into cosmic-ray transport from radio halos in edge-on galaxies
• Nearby galaxies in the LOFAR Two-metre Sky Survey II. The magnetic field-gas relation
• CHANG-ES XXV: HI Imaging of Nearby Edge-on Galaxies -- Data Release 4
• eDIG-CHANGES I: Extended Hα Emission from the Extraplanar Diffuse Ionized Gas (eDIG) around CHANG-ES Galaxies
• Multi-scale decomposition of astronomical maps -- a constrained diffusion method
• CHANG-ES XXXII: Spatially Resolved Thermal/Nonthermal Separation from Radio Data Alone -- New Probes into NGC 3044 and NGC 5775
• CHANG-ES: XXXVI. The thin and thick radio discs