Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: "Leading blob" model in a stochastic acceleration scenario: the case of
  the 2009 flare of Mkn~501   Evidence for very hard, intrinsic $\gamma$-ray source spectra, as inferred
after correction for absorption in the extragalactic background light (EBL),
has interesting implications for the acceleration and radiation mechanisms
acting in blazars. A key issue so far has been the dependance of the hardness
of the $\gamma$-ray spectrum on different existing EBL models. The recent {\it
Fermi} observations of Mkn~501 now provide additional evidence for the presence
of hard intrinsic $\gamma$-ray spectra independent of EBL uncertainties.
Relativistic Maxwellian-type electron energy distributions that are formed in
stochastic acceleration scenarios offer a plausible interpretation for such
hard source spectra. Here we show that the combined emission from different
components with Maxwellian-type distributions could in principle also account
for more softer and broader, power law-like emission spectra. We introduce a
"leading blob" scenario, applicable to active flaring episodes, when one (or
few) of these components become distinct over the "background" emission,
producing hard spectral features and/or hardening of the observed spectra. We
show that this model can explain the peculiar high-energy characteristics of
Mkn~501 in 2009, with evidence for flaring activity and strong spectral
hardening at the highest $\gamma$-ray energies.

26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn