J/A+A/632/A10 NGC 4631 total intensity images (Mora-Partiarroyo+, 2019)
CHANG-ES. XIV. Cosmic-ray propagation and magnetic field strengths in the
radio halo of NGC 4631.
Mora-Partiarroyo S.C., Krause M., Basu A., Beck R., Wiegert T., Irwin J.,
Henriksen R., Stein Y., Vargas C.J., Heesen V., Walterbos R.A.M.,
Rand R.J., Heald G., Li J., Kamieneski P., English J.
<Astron. Astrophys. 632, A10 (2019)>
=2019A&A...632A..10M 2019A&A...632A..10M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Radio continuum
Keywords: galaxies: halos - radio continuum: galaxies -
galaxies: magnetic fields - galaxies: interactions - galaxies: spiral
Abstract:
NGC 4631 is an interacting galaxy that exhibits one of the largest,
gaseous halos observed among edge-on galaxies. We aim to examine the
synchrotron and cosmic-ray propagation properties of its disk and halo
emission with new radio continuum data.
Radio continuum observations of NGC 4631 were performed with the Karl
G. Jansky Very Large Array at C-band (5.99GHz) in the C and D array
configurations, and at L-band (1.57GHz) in the B, C, and D array
configurations. Complementary observations of NGC 4631 with the
Effelsberg telescope were performed at 1.42 and 4.85 GHz. The
interferometric total intensity data were combined with the
single-dish Effelsberg data in order to recover the missing
large-scale total power emission. The thermal and nonthermal
components of the total radio emission were separated by estimating
the thermal contribution through the extinction-corrected Hα
emission. The Hα radiation was corrected for extinction using a
linear combination of the observed Hα and 24µm data.
NGC 4631 has a global thermal fraction at 5.99(1.57)GHz of 14±3%
(5.4±1.1%). The mean scale heights of the total emission in the
radio halo (thick disk) at 5.99(1.57)GHz are 1.79±0.54kpc
(1.75±0.27kpc) and have about the same values for the synchrotron
emission. The total magnetic field of NGC 4631 has a mean strength of
<Beq≳=9µG in the disk, and a mean strength of <Beq≳=7µG in the
halo. We also studied a double-lobed background radio galaxy southwest
of NGC 4631, which is an FR II radio galaxy according to the
distribution of spectral index across the lobes.
From the halo scale heights we estimated that the radio halo is
escape-dominated with convective cosmic ray propagation, and conclude
that there is a galactic wind in the halo of NGC 4631.
Description:
Radio polarimetric observations of NGC 4631 were performed with the
Karl G. Jansky Very Large Array (VLA) during its commissioning phase
through the project Continuum HAlos in Nearby Galaxies - an EVLA
Survey (CHANG-ES).
The data were taken at C-band (5.0-7.0GHz) in C and D array
configuration, and at L-band (1.25-1.50 and 1.65-1.90GHz) in the B, C,
and D array configurations.
Observations of NGC 4631 with the 100m Effelsberg telescope centered
at 4.85GHz (0.5GHz bandwidth) were performed in 2014 with the
dual-beam receiver (Project 114-13).
We present total intensity images of NGC4631.
Objects:
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RA (2000) DE Designation(s)
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12 42 08.01 +32 32 29.4 NGC 4631 = UGC 7865
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 178 3 List of fits images
fits/* . 3 Individual fits images
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See also:
J/A+A/623/A33 : NGC 4666 polarization maps (Stein+, 2019)
J/A+A/632/A11 : Radio images of NGC 4631 (Mora-Partiarroyo+, 2019)
J/A+A/632/A12 : NGC 891 and NGC 4565 radio images (Schmidt+, 2019)
J/A+A/632/A13 : NGC 4013 radio and polarization maps (Stein+, 2019)
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- 34 F7.5 GHz Freq Observed frequency
36- 38 I3 Kibyte size Size of FITS file
40- 85 A46 --- FileName Name of FITS file, in subdirectory fits
87-178 A92 --- Title Title of the FITS file
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Acknowledgements:
Silvia Carolina Mora Partiarroyo, silvia.carolina.mora(at)gmail.com
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
Stein et al., Paper XIII 2019A&A...623A..33S 2019A&A...623A..33S, Cat. J/A+A/623/A33
Mora Partiarroyo et al., Paper XV 2019A&A...632A..11M 2019A&A...632A..11M, Cat. J/A+A/632/A11
Schmidt et al., Paper XVI 2019A&A...632A..12S 2019A&A...632A..12S, Cat. J/A+A/632/A12
Vargas et al., Paper XVII 2019ApJ...881...26V 2019ApJ...881...26V
Stein et al., Paper XIX 2019A&A...632A..13S 2019A&A...632A..13S, Cat. J/A+A/632/A13
Irwin et al., Paper XX 2019AJ....158...21I 2019AJ....158...21I
(End) Patricia Vannier [CDS] 10-Sep-2019