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