Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A study of young radio-loud AGN using space-VLBI   Gigahertz Peaked Spectrum (GPS) sources form a key element in the study of
the onset and evolution of radio-loud AGN, since they are most likely the young
counterparts of extended radio sources. Here we discuss space-VLBI observations
of GPS sources, which enable us to obtain unprecedented angular resolution at
frequencies near their spectral turnovers. Observed peak brightness
temperatures of Log[T]=10.5-11 Kelvin indicate that synchrotron self absorption
is responsible for their spectral turnovers. This is in close agreement with
previous size - spectral turnover statistics for GPS sources. The combination
of these new space-VLBI observations with ground-based VLBI observations taken
at an earlier epoch, confirm the young ages for the most compact GPS galaxies
of several hundred years.

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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg