J/A+A/628/A69       LOFAR 143MHz images of 3C 236             (Shulevski+, 2019)

First look at the giant radio galaxy 3C 236 with LOFAR. Shulevski A., Barthel P.D., Morganti R., Harwood J.J., Brienza M., Shimwell T.W., Rottgering H.J.A., White G.J., Callingham J.R., Mooney S., Rafferty D.A. <Astron. Astrophys. 628, A69 (2019)> =2019A&A...628A..69S 2019A&A...628A..69S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, Seyfert ; Galaxies, radio Keywords: galaxies active - radio continuum: galaxies - galaxies: individual: 3C 236 Abstract: We have examined the giant radio galaxy 3C 236 using LOFAR at 143MHz down to an angular resolution of 7 arcseconds, in combination with observations at higher frequencies. We used the low frequency data to derive spectral index maps with the highest resolution yet at these low frequencies. We confirm a previous detection of an inner hotspot in the north-west lobe and for the first time observe that the south-east lobe hotspot is in fact a triple hotspot, which may point to an intermittent source activity. Also, the spectral index map of 3C 236 shows that the spectral steepening at the inner region of the northern lobe is prominent at low frequencies. The outer regions of both lobes show spectral flattening, in contrast with previous high frequency studies. We derive spectral age estimates for the lobes, as well as particle densities of the IGM at various locations. We propose that the morphological differences between the lobes are driven by variations in the ambient medium density as well as the source activity history. Description: LOFAR 143MHz images, 20" and 6" resolution Objects: --------------------------------------------------- RA (2000) DE Designation(s) --------------------------------------------------- 10 06 01.75 +34 54 10.4 3C 236 = OHIO L 305 --------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file list.dat 158 2 List of fits files fits/* . 2 Individual fits files -------------------------------------------------------------------------------- See also: J/A+A/549/A58 : 3C 236 CO maps (Labiano+, 2013) J/A+A/617/A38 : The hydrogen gas outflow in 3C236 (Schulz+, 2018) Byte-by-byte Description of file: list.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 9 F9.5 deg RAdeg Right Ascension of center (J2000) 10- 18 F9.5 deg DEdeg Declination of center (J2000) 20- 23 I4 --- Nx Number of pixels along X-axis 25- 28 I4 --- Ny Number of pixels along Y-axis 30- 50 A21 "datime" Obs.date Observation date 52- 58 F7.5 MHz Freq Observed frequency 60- 64 I5 Kibyte size Size of FITS file 66-115 A50 --- FileName Name of FITS file, in subdirectory fits 118-158 A41 --- Title Title of the FITS file -------------------------------------------------------------------------------- Acknowledgements: Aleksandar Shulevski, a.shulevski(at)uva.nl
(End) Patricia Vannier [CDS] 28-Jul-2019
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