GMRT observations of IC 711 - The longest head-tail radio galaxy known
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by
zutopian
GMRT observations of IC 711 - The longest head-tail radio galaxy known
We present low-frequency, Giant Metrewave Radio Telescope (GMRT) observations at 240, 610 and 1300 MHz of IC 711, a narrow angle tail (NAT) radio galaxy. The galaxy lies in Abell cluster 1314 (redshift 0.034) and has a long radio tail of total angular extent 17 arcmin, corresponding to a projected linear size of 700 kpc. This makes it the longest head-tail radio galaxy known. The objectives of the GMRT observations were to investigate the diffuse-emission of the long tail structure at low frequencies. The radio structure, especially initial 10 arcmin of tail being a long straight feature, does not seem to be consistent with a simple circular motion around the cluster center, as previously suggested in the literature. Two sharp bends after the straight section of the tail cast doubt on the prevailing idea in the literature that the long narrow tails represent trails left behind by the fast moving parent optical galaxy with respect to the cluster medium, as the optical galaxy could not have undergone such sharp bends in its path, under any conceivable gravitational influence of some individual galaxy or of the overall cluster gravitational potential. In fact the tail does not seem to have been influenced by the gravitational field of any of the cluster-member galaxy. The radio tail shows a break in the spectrum. We derive an expression for the minimum energy in the case of a spectral break, in order to do the minimum energy calculation in diffuse tail regions of IC 711.
Shweta Srivastava, Ashok K. Singal
(Submitted on 25 Oct 2016)
https://arxiv.org/abs/1610.07783Posted
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by
zutopian
IC 711 has been "The longest head-tail radio galaxy known" for 40 years.:
IC 711 - The longest head-tail galaxy known
Authors: Vallee, J. P.; Roger, R. S.The scale size of the largest structure in head-tail galaxies is not well known. Previous observations of the head-tail galaxy IC 711 (Vallée and Wilson, 1976) have shown its tail to extend 13 arcmin (700 kpc for H0 = 50 km s-1Mpc-1) beyond the optical galaxy, making it then the longest head-tail galaxy known. New observations at a longer wavelength of 74 cm with the synthesis telescope at Penticton show that the radio tail extends still further, to at least 17 arcmin (930 kpc), retaining its status as the longest head-tail galaxy known today. Some theoretical models for the origin of such galaxies are discussed with particular reference to IC 711.
Publication: Astronomical Journal (ISSN 0004-6256), vol. 94, July 1987, p. 1-6.
Publication Date: 07/1987
http://adsabs.harvard.edu/cgi-bin/bib_query?1987AJ.....94....1VPosted