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Tabl e 6. 4
Search query used to locate articles for co-citation
analysis on black holes
Source: Web of science Description
Topic (Blackhole* or black hole*) and galax*
Database SCI expanded
Language English
Document type Article
Time span 1981-2000
* is a wildcard in the search query. For example, both Blackhole
and Blackholes would be relevant
articles in English from the SCI Expanded database dated between 1981 and 2000.
All matched to the query in at least one of the fields: titles, abstracts, and keywords.
Altogether these articles cited 58,315 publications, written by 58,148 authors.
We conducted both author co-citation analysis (ACA) and document co-citation
analysis (DCA) in order to detect the dynamics of prevailing paradigms. We chose
30 citations as the entry threshold for ACA and 20 citations for DCA. Ultimately,
373 authors and 221 publications were identified. We then generated three models of
the periods: 1981-1990, 1991-1995, and 1996-2000. The co-citation networks were
based on the entire range of citation data (1981-2000). The citation landscape in
each period conforms how often each article was cited within a particular sampling
window. In this topic, we only describe the results of a document co-citation analysis
for this case study.
In document co-citation analysis (DCA), we visualized a co-citation network of
221 top-cited publications. We particularly examined citation profiles in the context
of co-citation structure. Articles with more than 20 citations were automatically
labeled on semi-transparent panels in the scene. These panels always face to the
viewer. The landscape of the 1981-1990 period is shown as a flat plane - this
landscape obviously pre-dated the existence of the majority of the 221 publications.
The visualization landscape of the period of 1991-1995 is showing an interesting
pattern - three distinct clusters are clearly visible in peripheral areas of the co-
citation network. M-31 has been regarded as one of the strongest supportive cases
for the AGN paradigm. Alan Dressler and John Kormendy are known for their
work within the AGN paradigm. One of the clusters included articles from both
of them regarding the evidence for supermassive black holes in M-31. Another
cluster is more theoretically oriented, including articles from Martin Rees, who
was a pioneer of the theory that giant black holes may provide the power at
quasars' energetic centers. In addition, Martin Ree's nearest neighbor in the
document co-citation network is Lynden-Bell's article. Lynden-Bell provided the
most convincing argument for the AGN paradigm and showed that nuclear reactions
alone would have no way to power quasars. The cluster at the far end includes
ShakuraIvanovich's article on black holes in binary systems, whereas the large area
in the center of the co-citation network remains unpopulated within this period.
A useful feature of a Pathfinder network is that the most cited articles tend to locate
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