Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the origin of the soft photons of the high synchrotron peaked blazar
  : PKS 1424+240   PKS 1424+240 is a distant very high energy gamma-ray BL Lac object with
redshift $z=0.601$. It was found that pure synchrotron self-Compton (SSC)
process normally need extreme input parameters (e.g., very low magnetic field
intensity and extraordinarily large Doppler factor) to explain its
multi-wavelength spectral energy distributions (SEDs). To avoid the extreme
model parameters, different models have been proposed (e.g., two-zone SSC model
or lepto-hadronic model). In this work, we employ the traditional one-zone
leptonic model after including a weak external Compton component to re-explore
the simultaneous multi-wavelength SEDs of PKS 1424+240 in both high (2009) and
low (2013) states. We find that the input parameters of magnetic field and
Doppler factor are roughly consistent with those of other BL Lacs if a weak
external photon field from either broad line region (BLR) or the dust torus.
However, the required energy density of seed photons from BLR or torus is about
3 orders of magnitude less than that constrained in luminous quasars (e.g.,
flat-spectrum radio quasars, FSRQs). This result suggests that the BLR/torus in
BL Lacs is much weaker than that of luminous FSRQs (but not fully disappear),
and the inverse-Compton of external photons from BLR/torus may still play a
role even in high synchrotron peaked blazars.

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The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: math
15
The categories of this paper are: nucl-ex
29
The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys