Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovery of a high confidence soft lag from an X-ray flare of Markarian
  421   We present the X-ray variability properties of the X-ray and TeV bright
blazar Mrk 421 with a ~60 ks long XMM-Newton observation performed on November
9-10, 2005. The source experienced a pronounced flare, of which the inter-band
time lags were determined with a very high confidence level. The soft (0.6-0.8
keV) X-ray variations lagged the hard (4-10 keV) ones by 1.09 ks, and the soft
lag increases with increasing difference in the photon energy. The
energy-dependent soft lags can be well fitted with the difference of the
energy-dependent cooling timescales of the relativistic electron distribution
responsible for the observed X-ray emission, which constrains the magnetic
field strength and Doppler factor of the emitting region to be
B\delta^(1/3)~1.78 Gauss.

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The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
30
The categories of this paper are: q-alg