The optical spectra of X-shaped radio galaxies - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado

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Abstract: X-shaped radio galaxies are defined by their peculiar large-scale radiomorphology. In addition to the classical double-lobed structure they have apair of low-luminosity wings that straddles the nucleus at almost right anglesto the active lobes, thus giving the impression of an -X-. In this paper westudy for the first time the optical spectral properties of this object classusing a large sample ~50 sources. We find that the X-shaped radio populationis composed roughly equally of sources with weak and strong emission linespectra, which makes them, in combination with the well-known fact that theypreferentially have radio powers intermediate between those of Fanaroff-Rileytype I FR I and type II FR II radio galaxies, the archetypal transitionpopulation. We do not find evidence in support of the proposition that theX-shape is the result of a recent merger: X-shaped radio sources do not haveunusually broad emission lines, their nuclear environments are in general notdusty, and their host galaxies do not show signs of enhanced star formation.Instead, we observe that the nuclear regions of X-shaped radio sources haverelatively high temperatures. This finding favours models, which propose thatthe X-shape is the result of an overpressured environment.

Autor: Hermine Landt 1, Chi C. Cheung 2,3, Stephen E. Healey 4 1 University of Melbourne, 2 NASA Goddard Space Flight Center, 3 NRL, 4 S


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