Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hard X-ray and ultraviolet emission during the 2011 June 7 solar flare   The relationship between X-ray and UV emission during flares, particularly in
the context of quasi-periodic pulsations, remains unclear. To address this, we
study the impulsive X-ray and UV emission during the eruptive flare of 2011
June 7 utilising X-ray imaging from RHESSI and UV 1700A imaging from SDO/AIA.
This event is associated with quasi-periodic pulsations in X-ray and possibly
UV emission, as well as substantial parallel and perpendicular motion of the
hard X-ray footpoints.
  The motion of the footpoints parallel to the flare ribbons is unusual; it is
shown to reverse direction on at least two occasions. However, there is no
associated short-timescale motion of the UV bright regions. Additionally, we
find that the locations of the brightest X-ray and UV regions are different,
particularly during the early portion of the flare impulsive phase, despite
their integrated emission being strongly correlated in time. Correlation
analysis of measured flare properties, such as the footpoint separation, flare
shear, photospheric magnetic field and coronal reconnection rate, reveals that
- in the impulsive phase - the 25 - 50 keV hard X-ray flux is only weakly
correlated with these properties, in contrast to previous studies.
  We characterise this event in terms of long-term behaviour, where the X-ray
nonthermal, thermal, and UV emission sources appear temporally and spatially
consistent, and short-term behaviour, where the emission sources are
inconsistent and quasi-periodic pulsations are a dominant feature requiring
explanation. We suggest that the short timescale behaviour of hard X-ray
footpoints, and the nature of the observed quasi-periodic pulsations, is
determined by fundamental, as-yet unobserved properties of the reconnection
region and particle acceleration sites. This presents a challenge for current
three-dimensional flare reconnection models.

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The categories of this paper are: math
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin
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The categories of this paper are: adap-org
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: hep-th