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J/MNRAS/476/158     Radio haloes in nearby galaxies              (Heesen+, 2018)

Radio haloes in nearby galaxies modelled with 1D cosmic-ray transport using SPINNAKER. Heesen V., Krause M., Beck R., Adebahr B., Bomans D.J., Carretti E., Dumke M., Heald G., Irwin J., Koribalski B.S., Mulcahy D.D., Westmeier T., Dettmar R.-J. <Mon. Not. R. Astron. Soc. 476, 158-183 (2018)> =2018MNRAS.476..158H (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Radio continuum Keywords: radiation mechanisms: non-thermal - methods: numerical - cosmic rays - galaxies: haloes - galaxies: magnetic fields - radio continuum: galaxies Abstract: We present radio continuum maps of 12 nearby (D≤27Mpc), edge-on (i≥76°), late-type spiral galaxies mostly at 1.4 and 5GHz, observed with the Australia Telescope Compact Array, Very Large Array, Westerbork Synthesis Radio Telescope, Effelsberg 100-m and Parkes 64-m telescopes. All galaxies show clear evidence of radio haloes, including the first detection in the Magellanic-type galaxy NGC 55. In 11 galaxies, we find a thin and a thick disc that can be better fitted by exponential rather than Gaussian functions. We fit our SPINNAKER (SPectral INdex Numerical Analysis of K(c)osmic-ray Electron Radio-emission) 1D cosmic-ray transport models to the vertical model profiles of the non-thermal intensity and to the non-thermal radio spectral index in the halo. We simultaneously fit for the advection speed (or diffusion coefficient) and magnetic field scale height. In the thick disc, the magnetic field scale heights range from 2 to 8kpc with an average across the sample of 3.0±1.7kpc; they show no correlation with either star-formation rate (SFR), SFR surface density (SigmaSFR) or rotation speed (Vrot). The advection speeds range from 100 to 700km/s and display correlations of V∝SFR0.36±0.06 and V∝SigmaSFR0.39±0.09; they agree remarkably well with the escape velocities (0.5≤V/V_esc≤2), which can be explained by cosmic-ray driven winds. Radio haloes show the presence of disc winds in galaxies with SigmaSFR>10-3M/yr/kpc2 that extend over several kpc and are driven by processes related to the distributed star formation in the disc. Description: We present radio continuum observations of 12 nearby (D=2-27Mpc) edge-on galaxies at two different frequencies, namely at 1.4 and 5GHz (one galaxy at 8.5GHz instead of 5GHz). Our sample includes 11 late-type spiral (Sb or Sc) galaxies and one Magellanic-type barred galaxy (SBm), which are all highly inclined (i≥76°). As part of our study we have obtained several additional radio continuum maps. We make these maps publicly available (as well as all the other radio continuum maps in the paper). For 4 galaxies (NGC 55, 253, 891 and 4631) we have used single-dish maps, to correct for the missing zero-spacing flux where necessary. The Effelsberg maps of NGC 253 and 4631 were already presented in Heesen et al. (2009A&A...494..563H) and Mora & Krause (2013A&A...560A..42M), respectively, and the Effelsberg map of NGC 891 was already presented in Dumke (1997, PhD thesis, University of Bonn). We present these maps for completeness. The 4.80-GHz map of NGC 55 obtained with the 64-m Parkes telescope is so far unpublished. Furthermore, we show two maps of NGC 4631 at 1.35 and 1.65GHz observed with the VLA in D- configuration (R. Beck 2016, priv. comm.). The data were observed in August 1996, with 12 h on-source (ID: AG486) and reduced in standard fashion with AIPS. The maps have an angular resolution of 52 arcsec, so that we did not use them in the analysis, but they also show the halo of this galaxy very well. Lastly, we obtained maps of three further edge-on galaxies observed with the VLA (NGC 4157, 4217 and 4634). We reduced the data as described in Section 2, but since we had only one frequency available and no spectral index map, we did not use them in the analysis. The maps of NGC 4157 and 4217 were created by re-reducing archive data (IDs AI23, AF85, AH457 and AS392 for NGC 4157 and ID AM573 for NGC 4217). The map of NGC 4634 was created by using so far unpublished data from the VLA (ID: AD538). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table3.dat 123 12 Radio properties of our sample galaxies list.dat 150 32 List of fits images fits/* 0 32 Individual fits images
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Name Galaxy name 9- 18 F10.6 deg RAdeg Right Ascension (J2000) 20- 29 F10.6 deg DEdeg Declination (J2000) 31- 35 F5.2 arcsec thetaFWHM Agular resolution, referred to as the full width at half maximum (FWHM), of the circular synthesized beam 37- 40 F4.2 GHz nu1 Observing frequency nu1 42- 45 F4.2 GHz nu2 Observing frequency nu2 47- 52 F6.4 Jy S1 Intergrated flux density at nu1 54- 59 F6.4 Jy e_S1 Error of the flux density at nu1 61- 66 F6.4 Jy S1int Non-thermal integrated flux density at nu1 68- 73 F6.4 Jy e_S1int Error of the flux density at nu1int 75- 80 F6.4 Jy S2 Intergrated flux density at nu2 82- 87 F6.4 Jy e_S2 Error of the flux density at nu2 89- 94 F6.4 Jy S2int Non-thermal integrated flux density at nu2 96-101 F6.4 Jy e_S2int Error of the flux density at nu2int 103-107 F5.2 --- alpha Integrated radio spectral index between nu1 and nu2 109-112 F4.2 --- e_alpha Error on alpha 114-118 F5.2 --- alphaint Integrated non-thermal radio spectral index between nu1 and nu2 120-123 F4.2 --- e_alphaint Error on alphaint
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Name Galaxy name 9- 17 F9.5 deg RAdeg Right Ascension of center (J2000) 18- 26 F9.5 deg DEdeg Declination of center (J2000) 28- 31 I4 --- Nx Number of pixels along X-axis 33- 36 I4 --- Ny Number of pixels along Y-axis 38- 63 A26 --- Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.ssssss) 65- 71 F7.5 GHz Freq Observed frequency 73- 78 I6 Kibyte size Size of FITS file 80-113 A34 --- FileName Name of FITS file, in subdirectory fits 115-150 A36 --- Title Title of the FITS file
Acknowledgements: Volker Heesen, volker.heesen(at)
(End) Patricia Vannier [CDS] 23-Feb-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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