Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Particle acceleration in relativistic magnetic flux-merging events   Using analytical and numerical methods (fluid and particle-in-cell
simulations) we study a number of model problems involving merger of magnetic
flux tubes in relativistic magnetically-dominated plasma. Mergers of
current-carrying flux tubes (exemplified by the two dimensional `ABC'
structures) and zero total current magnetic flux tubes are considered. In all
cases regimes of spontaneous and driven evolution are investigated. We identify
two stages of particle acceleration during flux mergers: (i) fast explosive
prompt X-point collapse and (ii) ensuing island merger. The fastest
acceleration occurs during the initial catastrophic X-point collapse, with the
reconnection electric field of the order of the magnetic field. During the
X-point collapse particles are accelerated by charge-starved electric fields,
which can reach (and even exceed) values of the local magnetic field. The
explosive stage of reconnection produces non-thermal power-law tails with
slopes that depend on the average magnetization $\sigma$. For plasma
magnetization $\sigma \leq 10^2$ the spectrum power law index is $p> 2$; in
this case the maximal energy depends linearly on the size of the reconnecting
islands. For higher magnetization, $\sigma \geq 10^2$, the spectra are hard,
$p< 2$, yet the maximal energy $\gamma_{max}$ can still exceed the average
magnetic energy per particle, $ \sim \sigma$, by orders of magnitude (if $p$ is
not too close to unity). The X-point collapse stage is followed by magnetic
island merger that dissipates a large fraction of the initial magnetic energy
in a regime of forced magnetic reconnection, further accelerating the
particles, but proceeds at a slower reconnection rate.

15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs