J/A+A/623/A33 NGC 4666 polarization maps (Stein+, 2019)
CHANG-ES. XIII: Transport processes and the magnetic fields of NGC 4666:
indication of a reversing disk magnetic field.
Stein Y., Dettmar R.-J., Irwin J., Beck R., Wezgowiec M., Miskolczi A.,
Krause M., Heesen V., Wiegert T., Heald G., Walterbos R.A.M., Li J.-T.,
Soida M.
<Astron. Astrophys. 623, A33 (2019)>
=2019A&A...623A..33S 2019A&A...623A..33S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Magnetic fields ; Polarization
Keywords: galaxies: spiral - galaxies: individual: NGC 4666 - surveys -
polarization - radio continuum: galaxies - galaxies: magnetic fields
Abstract:
The observation of total and linearly polarized synchrotron radiation
of spiral galaxies in the radio continuum reveals the distribution and
structure of their magnetic fields. By observing these, information
about the proposed dynamo processes that preserve the large-scale
magnetic fields in spiral galaxies can be gained. Additionally, by
analyzing the synchrotron intensity, the transport processes of cosmic
rays into the halo of edge-on spiral galaxies can be investigated.
We analyze the magnetic field geometry and the transport processes of
the cosmic rays of the edge-on spiral starburst galaxy NGC 4666 from
CHANG-ES radio data in two frequencies; 6 GHz (C-band) and 1.5 GHz
(L-band). Supplementary X-ray data are used to investigate the hot gas
in NGC 4666.
We determine the radio scale heights of total power emission at both
frequencies for this galaxy. We show the magnetic field orientations
derived from the polarization data. Using rotation measure (RM)
synthesis we further study the behavior of the RM values along the
disk in C-band to investigate the large-scale magnetic-field pattern.
We use the revised equipartition formula to calculate a map of the
magnetic field strength. Furthermore, we model the processes of
cosmic-ray transport into the halo with the 1D SPINNAKER model.
The extended radio halo of NGC 4666 is box-shaped and is probably
produced by the previously observed supernova-driven superwind. This
is supported by our finding of an advective cosmic-ray transport such
as that expected for a galactic wind. The scaleheight analysis
revealed an asymmetric halo above and below the disk as well as
between the two sides of the major axis. A central point source as
well as a bubble structure is seen in the radio data for the first
time. Our X-ray data show a box-shaped hot halo around NGC 4666 and
furthermore confirm the AGN nature of the central source. NGC 4666 has
a large-scale X-shaped magnetic field in the halo, as has been
observed in other edge-on galaxies. The analysis furthermore revealed
that the disk of NGC 4666 shows hints of field reversals along its
radius, which is the first detection of this phenomenon in an external
galaxy.
Description:
We present all figures of the paper in fits-format named in
correspondence to the figure in the paper:
1. JVLA-CHANG-ES data: 6cm (Stokes I,Q,U) and 20cm (StokesI, polarized
Intensity and polarization Angle from RM-synthesis)
2. XMM-Newton image 3. old VLA 6cm (Stokes I,Q,U)
Please see paper and Irwin et al. (2012AJ....144...43I 2012AJ....144...43I,
2012AJ....144...44I 2012AJ....144...44I) for details on the calibration and imaging.
Objects:
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RA (2000) DE Designation(s)
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12 45 08.68 -00 27 42.9 NGC 4666 = MRC 1242-001
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 250 17 List of fits files
fits/* . 17 Individual fits files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 46 A19 "datime" Obs.date Observation date
48- 51 I4 Kibyte size Size of FITS file
53-113 A61 --- FileName Name of FITS file, in subdirectory fits
115-250 A136 --- Title Title of the FITS file
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Acknowledgements:
Yelena Stein, yelena.stein(at)astro.unistra.fr
References:
Irwin et al., Paper I 2012AJ....144...43I 2012AJ....144...43I
Irwin et al., Paper II 2012AJ....144...44I 2012AJ....144...44I
Irwin et al., Paper III 2013AJ....146..164I 2013AJ....146..164I
Wiegert et al., Paper IV 2015AJ....150...81W 2015AJ....150...81W
Irwin et al., Paper V 2015ApJ...809..172I 2015ApJ...809..172I
Li et al., Paper VI 2016MNRAS.456.1723L 2016MNRAS.456.1723L
Damas-Segovia et al., Paper VII 2016ApJ...824...30D 2016ApJ...824...30D
Irwin et al., Paper VIII 2017MNRAS.464.1333I 2017MNRAS.464.1333I
Krause et al., Paper IX 2018A&A...611A..72K 2018A&A...611A..72K
Vargas et al., Paper X 2018ApJ...853..128V 2018ApJ...853..128V
Irwin et al., Paper XI 2018MNRAS.476.5057I 2018MNRAS.476.5057I
Miskolczi et al., Paper XII 2019A&A...622A...9M 2019A&A...622A...9M
(End) Patricia Vannier [CDS] 14-Feb-2019