Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Establishing the Spectral Turnover of Blazar PKS 2155-304 as an Outcome
  of Radiative Losses   The broad band optical/UV and X-ray spectra of blazars have been often
modeled as synchrotron component arising from a broken power-law distribution
of electrons. A broken power-law distribution is expected, since the high
energy electrons undergo radiative losses effectively. The change in the energy
index should then be approximately 1 and corresponds to a spectral index
difference of 0.5. However, one of the long outstanding problems has been that
the observed index change is significantly different. On the other hand, recent
high quality observations of blazars suggest that their local spectra may not
be a power-law, instead have a slight curvature and often represented by a log
parabola model. Using XMM-Newton observations spanning over 12 years for the BL
Lac PKS 2155-304, we show that the optical/UV and X-ray spectra can be well
represented by a broken log parabola model. Further, we show that such a
spectrum can indicate the energy dependence of the electron escape timescale
from the main acceleration zone. This novel approach, besides addressing the
observed difference in the photon spectral indices, also tries to explain the
spectral turn over in far UV/soft X-rays as a result of the radiative losses.

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The categories of this paper are: supr-con
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
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The categories of this paper are: q-fin
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
16
The categories of this paper are: stat
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The categories of this paper are: solv-int
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
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The categories of this paper are: quant-ph
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The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga