Volume 394, Number 1, October IV 2002
|Page(s)||39 - 45|
|Section||Cosmology (including clusters of galaxies)|
|Published online||04 October 2002|
On the origin of X-shaped radio-sources: New insights from the properties of their host galaxies*
Istituto Nazionale di Astrofisica (INAF) – Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese, Italy
2 Universitatea din Bucuresti, Facultatea de fizica atomica si nucleara, Bucuresti-Magurele, PO-BOX MG-11, Romania
3 Istituto di Fisica Generale, Universitá di Torino, Via Giuria 1, 10125 Torino, Italy
Corresponding author: A. Capetti, firstname.lastname@example.org
Accepted: 19 July 2002
A significant fraction of extended radio sources presents a peculiar X-shaped radio morphology: in addition to the classical double lobed structure, radio emission is also observed along a second axis of symmetry in the form of diffuse wings or tails. We re-examine the origin of these extensions relating the radio morphology to the properties of their host galaxies. The orientation of the wings shows a striking connection with the structure of the host galaxy as they are preferentially aligned with its minor axis. Furthermore, wings are only observed in galaxies of high projected ellipticity. Hydrodynamical simulations of the radio-source evolution show that X-shaped radio-sources naturally form in this geometrical situation: as a jet propagates in a non-spherical gas distribution, the cocoon surrounding the radio-jets expands laterally at a high rate producing wings of radio emission, in a way that is reminiscent of the twin-exhaust model for radio-sources.
Key words: galaxies: active / galaxies: elliptical and lenticular; cD / galaxies: jets
Based on observations obtained at the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Centro Galileo Galilei of the CNAA (Consorzio Nazionale per l'Astronomia e l'Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.
© ESO, 2002
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