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CosmoPlMeeting2006 -
CosmoPlMeeting2006Program
COSMO-PL SPRING MEETING 2006
title: AGN recycling - birth and death
abstract:
Signatures of the re-occurrence of activity in radio-loud AGNs,
indicated either by the so-called double-double or X-shaped structures,
have been observed in a number of radio sources. All such objects known to
date have linear sizes of the order of a megaparsec. A number of the sources
that are appreciably more compact than this, but that exhibit hints of a
past phase of activity, were found in the VLA FIRST survey. Their structures
show symmetric relic lobes straddling relatively bright, unresolved cores.
Observations of the cores of 15 such structures with MERLIN at
5 GHz have shown that four of them are doubles or core-jets on the
subarcsecond scale. Misalignments between the axis
of the inner structure and the line connecting the fitted maxima of the
arcminute-scale relic lobes are clearly visible in three of the four sources.
From these results, we can infer that a rapid repositioning of
the central engine in each of these three radio sources is the most
plausible interpretation of the observed morphology and that a merger is
most likely the original cause of such a repositioning. In the case of
TXS 1033+026, the optical image extracted from the SDSS archives clearly
suggests that two objects separated by only 2.7 kpc (projected onto the
sky plane) are indeed merging.
--
AndrzejMarecki - 16 May 2006