Soon After the Birth of Radio Sources

Abstract

Abstract.Compact Symmetric Objects (CSOs) represent an early stage in the life of radio galaxies. Our kinematic studies over a 20 year timebase have unambiguously demonstrated that they expand fast and that the radio activity is recently born. The CSO evolution with time is however still a matter of investigation. If they are progenitors of the "classical double" radio sources, then in order to fit the the observed statistics of radio sources, CSOs must have decrease their luminosity and expansion speed with time. It is also possible that CSOs represent a phase of periodic activity of the central engine; in this case the presence of the old activity in the form of extended weak emission, should be observed.

Strong lensing reveals jets in a sub-microJy radio-quiet quasar

“…The results show a clear linear alignment of the three background sources, with two opposing jet components situated very close to the quasar core. This presentation suggests the morphology of a compact symmetric object (CSO), in which compact jets are located on the parsec-scale either side of the core Owsianik et al 2001). Observations of the rapid advancement of hotspots in several CSOs suggest that CSOs represent a population of very young radio loud sources, with ages under ∼1000 years (Readhead et al 1996;.…”

A Shrinking Compact Symmetric Object: J11584+2450?

“…Due to their rapid growth, age estimates for the emission from these objects can be obtained kinematically (Owsianik & Conway 1998;Taylor et al 2000), yielding ages ranging from tens to thousands of years. Less accurate spectroscopic models ( Readhead et al 1996;Murgia et al 1999;Gugliucci et al 2005) place CSOs at a few thousands of years old.…”

“…This distribution should not be taken as definitive, however, since Gugliucci et al concede it may be influenced by selection effects. One theory suggests that CSOs could be generally short-lived objects with only a small fraction of them surviving to become larger scale objects, while the remaining galaxies become permanently radio-quiet (Owsianik & Conway 1998). In a competing theory there exists a cyclic process where unsuccessful CSOs have multiple opportunities to grow into larger objects (O'Dea & Baum 1997).…”

Young Powerful Radio Sources and their Evolution

“…So far lobe proper motions have been measured in a handfull of the smallest CSOs by several authors ; ; Owsianik et al (2000); Polatidis et al(2000); Stanghellini et al, (2001a); Taylor et al (2000); Taylor and Vermeulen (1997); Tschager et al, 2000). Velocities between the edges of the two minilobes up to 0.4c have been found.…”