CHANG-ES XIX: Galaxy NGC 4013 -- a diffusion-dominated radio halo with plane-parallel disk and vertical halo magnetic fields

Abstract

Using the Continuum HAloes in Nearby Galaxies - an EVLA Survey (CHANG-ES) radio continuum data from the Karl G. Jansky Very Large Array (VLA) in two frequency bands (C-band, L-band), we analyzed the radio properties, including polarization and the transport processes of the CR electrons (CREs), in the edge-on spiral galaxy NGC 4013. Supplementary LOw-Frequency ARray (LOFAR) data at 150MHz are used to study the low-frequency properties of this galaxy and X-ray (Chandra, XMM-Newton) data are used to investigate the central region. The central point source dominates the radio continuum in both CHANG-ES bands, but no clear AGN classification is possible at this time. The scale height analysis shows that Gaussian fits, with halo scale heights of 1.2 kpc in C-band, 2.0 kpc in L-band, and 3.1 kpc at 150 MHz, better represent the intensity profiles than do exponential fits. The radio continuum halo of NGC 4013 in C-band is rather small, while the low-frequency LOFAR data reveal a large halo. The polarization data reveal plane-parallel, regular magnetic fields within the entire disk and vertical halo components out to heights of about 6 kpc indicating the presence of an axisymmetric field having a radial component pointing outwards. The mean magnetic field strength of the disk of NGC 4013 of 6.6 $\mu$G (using the revised equipartition formula) is rather small. The interaction and the low star formation rate (SFR) across the disk of NGC 4013 probably influence the appearance of its radio continuum. Several observable quantities give consistent evidence that the CR transport in the halo of NGC 4013 is diffusive: the frequency dependence of the synchrotron scale height, the disk/halo flux density ratio, the vertical profile of the synchrotron spectral index, the small propagation speed measured modeled with spinnaker, and the low temperature of the X-ray emitting hot gas.

24 pages, 27 figures, accepted for publication in A&A

References in corpus (25)

• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• The LOFAR Two-metre Sky Survey - II. First data release
• Revised equipartition & minimum energy formula for magnetic field strength estimates from radio synchrotron observations
• The Radio Spectral Energy Distribution and Star Formation Rate Calibration in Galaxies
• Evolution of magnetic fields in galaxies and future observational tests with the Square Kilometre Array
• The XMM-Newton EPIC Background and the production of Background Blank Sky Event Files
• Discovery of a Giant Stellar Tidal Stream Around the Disk Galaxy NGC 4013
• LeMMINGs. I. The eMERLIN legacy survey of nearby galaxies. 1.5-GHz parsec-scale radio structures and cores
• CHANG-ES IX: Radio scale heights and scale lengths of a consistent sample of 13 spiral galaxies seen edge-on and their correlations
• Radio haloes in nearby galaxies modelled with 1D cosmic-ray transport using SPINNAKER
• The reports of thick discs' deaths are greatly exaggerated: thick discs are NOT artefacts caused by diffuse scattered light
• CHANG-ES XV: Large-scale magnetic field reversals in the radio halo of NGC 4631
• 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 XVI: An in-depth view of the cosmic-ray transport in the edge-on spiral galaxies NGC 891 and NGC 4565
• Investigation of the cosmic ray population and magnetic field strength in the halo of NGC 891
• LOFAR MSSS: Flattening low-frequency radio continuum spectra of nearby galaxies
• CHANG-ES XX. High Resolution Radio Continuum Images of Edge-on Galaxies and their AGNs -- Data Release 3
• CHANG-ES X: Spatially-resolved Separation of Thermal Contribution from Radio Continuum Emission in Edge-on Galaxies
• A compiled catalog of rotation measures of radio point sources
• HERschel Observations of Edge-on Spirals (HEROES). IV. Dust energy balance problem
• An analytical dynamo solution for large-scale magnetic fields of galaxies
• Magnetic Spiral Arms in Galaxy Halos
• Exact axially symmetric galactic dynamos
• CHANG-ES XI: Circular Polarization in the Cores of Nearby Galaxies

Cited by in corpus (22)

• Magnetising the circumgalactic medium of disk galaxies
• CHANG-ES XXII: Coherent Magnetic Fields in the Halos of Spiral Galaxies
• Galactic Dynamos
• Nearby galaxies in LoTSS-DR2: insights into the non-linearity of the radio-SFR relation
• Magnetogenesis around the first galaxies: the impact of different field seeding processes on galaxy formation
• CHANG-ES XXI. Transport processes and the X-shaped magnetic field of NGC 4217: off-center superbubble structure
• 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
• The Halos and Environments of Nearby Galaxies (HERON) II: The outer structure of edge-on galaxies
• HALOGAS: Strong Constraints on the Neutral Gas Reservoir and Accretion Rate in Nearby Spiral Galaxies
• Can the Local Bubble explain the radio background?
• CHANG-ES XXXII: Spatially Resolved Thermal/Nonthermal Separation from Radio Data Alone -- New Probes into NGC 3044 and NGC 5775
• FEASTS Combined with Interferometry. III. The Low Column Density HI Around M51 and Possibility of Turbulent-mixing Gas Accretion
• Hot gas heating via magnetic arms in spiral galaxies. The case of M 83
• CHANG-ES: XXXVI. The thin and thick radio discs
• CHANG-ES XXXIV: Magnetic Field Structure in Edge-On Galaxies Characterising large-scale magnetic fields in galactic halos
• Exploring magnetised galactic outflows in starburst dwarf galaxies NGC 3125 and IC 4662
• CHANG-ES XXXVII. Effects of spectral aging on radio scale heights
• The Dust Polarisation and Magnetic Field Structure in the Centre of NGC253 with ALMA
• CHILLING: Continuum Halos in LVHIS Local Irregular Nearby Galaxies - Radio continuum spectral behavior of dwarf galaxies
• MEDUSA I. Tracing magnetic field structures in tidal arms of the dwarf-dwarf merger NGC 1487
• Turbulent Magnetic Dynamos with Halo Lags, Winds, and Jets