Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Signatures of restarted activity in core-dominated, triple radio sources
  selected from the FIRST survey   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 of \Delta PA
\ga 30 degr. 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. The inner parts of TXS 0818+214 and TXS 1312+563 could be
interpreted as double-lobed, and consequently, these sources could be of the
double-double type; but further multifrequency observations are necessary to
provide support for such an interpretation.

33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con