Morphology and environment of the radiogalaxies. The study: “Investigating the large-scale environment of wide-angle tailed radio galaxies in the local Universe” of V. Missaglia (UniTo, OATo) appeared on A&A

Radiogalaxies are galaxies characterized by intense emission of radio waves, primarily produced by relativistic particles in motion along magnetic field lines (known as synchrotron emission). This radio emission is the result of the activity of a supermassive black hole situated at the center of these galaxies, giving rise to a plasma jet that extends over thousands or even millions of light years. Following a classification proposed in 1974, radiogalaxies can be categorized into two classes: Faranoff-Riley galaxies of type I (FR I) and those of type II (FR II). This classification is based on the variation in radio emission intensity as one moves away from the galactic center: in FR I radiogalaxies, radio luminosity diminishes with distance from the center, whereas in FR II radiogalaxies, it increases as one approaches the lobes of the radio jet. Applying a similar approach, certain galaxies can be classified as “wide-angle tailed radio galaxies” (WATs), which exhibit a more intricate morphology in radio images, with the radio-emitting lobes assuming a “c” shape.

 

The distinction between FR I and FR II galaxies also stems from their evolutionary status and environment. Indeed, FR I galaxies are commonly observed at the cores of rich groups or clusters of galaxies, whereas FR II galaxies are generally more isolated. Likewise, WAT galaxies are often linked with rich galaxy clusters and tend to be the most luminous galaxies within their respective group. Their intricate morphology arises from pressure exerted by the intergalactic medium in motion relative to the galaxy, or from dynamic interactions among active galaxies.

 

The team of researchers, led by astronomer V. Missaglia (from the University of Turin, INAF – Astrophysical Observatory of Turin, INFN, and the Foundation for Research and Technology – Hellas), has analyzed three homogeneous samples of WAT galaxies in the Local Universe, focusing on their environmental characteristics. For this purpose, the astronomers have searched for companions of the WAT galaxies within the catalog generated by the SDSS (Sloan Digital Sky Survey). This study confirms the tendency of WAT radiogalaxies to be commonly linked with the most luminous galaxies in rich groups or clusters of galaxies. Besides, WAT galaxies are systematically found in more massive environments than the FR I and II galaxies. Moreover, across the range of distances covered by this study, the environment of the WAT galaxies remains quite consistent and does not vary with their distances from us. This property is not observed in the FR radiogalaxies. The findings of this study are described in the paper titled: “Investigating the large-scale environment of wide-angle tailed radio galaxies in the local Universe“, which has recently been published in the journal Astronomy & Astrophysics. Among the coauthors, is also listed the astronomer I. Pillitteri from the INAF – Astronomical Observatory of Palermo.

 

The figure (click here to visualize it entirely) shows three images obtained with the Very Large Array (VLA) of three radiogalaxies of the three types studied in this work: the FR I galaxy M84, the FR II galaxy 3C334, and the WAT galaxy 3C465.

 

Mario Giuseppe Guarcello  ( follow mariospiegacose) ( mariospiegacose) ( follow mariospiegacose)

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