Other
Scientific paper
Dec 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997phdt.......127g&link_type=abstract
PhD Thesis, The University of Manchester, 400 pages
Other
1
Radio Galaxies, Individual: Hercules A, 3C388, Radio Emission, X-Ray Emission, Magnetic Fields
Scientific paper
We made VLA radio total intensity and polarization observations at the L-band A, B and C configurations at 1665, 1435, 1365 and 1295 MHz and at the X-band B, C and D configurations at 8465 and 8415 MHz to study the environment of the powerful radio galaxy Hercules A. With the purpose of studying the depolarization of Hercules A and the external magnetic field, we have combined the L-band A+B+C data with the C-band (4873 MHz) B+C+D data (retrieved from the archive) at 1.4'' resolution and the X-band C+D data with the C-band B+C+D data at 2.23'' resolution. We have found that Hercules A exhibits a strong Laing-Garrington effect: the western side of the radio emission is more depolarized than the eastern side. The depolarization asymmetry between the two sides of the radio emission may be explained in terms of the relativistic beaming model as a simple geometric effect: Hercules A is embedded in a centrally condensed medium at an angle of ~= 50o to the line of sight. The stronger jet is on the near side of the source (eastern side) and hence it is seen through less depolarizing gas. We have produced spectral index maps that revealed steep spectrum extended radio emission, never observed before, surrounding the jets of Hercules A. We have also found that the more depolarized western side has a steeper spectrum than the less depolarized eastern side. We have also made ROSAT PSPC and HRI X-ray observations to study the intracluster gas in the Hercules A cluster. These have revealed an extended X-ray emission and a weak nuclear component. The total X-ray luminosity detected is ≈ 4.5 \cdot 1043 erg s-1 in the rest frame ROSAT energy band 0.12 to 2.77 keV. Our PSPC and HRI data suggest an elongation of the X-ray emission along the radio galaxy axis. The radio emission has a total extent of ~= 334 kpc and the X-ray emission of ≈ 880 kpc. We have found that the Hercules A cluster is a cooling flow cluster, which appears isothermal at large radii. The gas surrounding the radio galaxy has a temperature T ~= 3.6 \cdot 107 K. We estimated the central value of the external magnetic field strength by fitting a `cooling flow model' to the X-ray surface brightness profile and a two-power law model to the Faraday dispersion (Δ) profile obtained from the radio data. The estimated central electron density of no ~= 6.6 \cdot 103 m-3 reveals a dense environment in which Hercules A is situated. We found that the magnetic field is decreasing with radius and we have estimated a central value of 3 <~ Bo( μG) <~ 9. We have also made X-ray observations with the ROSAT HRI detector of the radio galaxy 3C388. The data suggest that the mostly centered X-ray emission, is roughly in the direction of the radio galaxy axis and its total extent is ~= 246 kpc.
No associations
LandOfFree
The Environment of Double Radio Sources Associated with Active Galactic Nuclei does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Environment of Double Radio Sources Associated with Active Galactic Nuclei, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Environment of Double Radio Sources Associated with Active Galactic Nuclei will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1663450