Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Supersoft X-rays reveal a classical nova in the M 31 globular cluster
  Bol 126   [Abridged] Classical novae (CNe) represent the main class of supersoft X-ray
sources (SSSs) in the central region of our neighbouring galaxy M 31. Only
three confirmed novae and three SSSs have been discovered in globular clusters
(GCs) of any galaxy so far, of which one nova and two SSSs (including the nova)
were found in M 31 GCs. To study the SSS state of CNe we carried out a
high-cadence X-ray monitoring of the M 31 central area with XMM-Newton and
Chandra. We analysed X-ray and optical data of a new transient X-ray source in
the M 31 GC Bol 126, discovered serendipitously in Swift observations. Our
optical data set was based on regular M 31 monitoring programmes from five
different small telescopes. Additionally, we made use of Pan-STARRS 1 data
obtained during the PAndromeda survey. Our observations reveal that the X-ray
source in Bol 126 is the third SSS in an M 31 GC and can be confirmed as the
second CN in the M 31 GC system. This nova is named M31N 2010-10f. Its
properties in the X-ray and optical regimes agree with a massive white dwarf
(M_WD >~ 1.3 M_sun) in the binary system. Incorporating the data on previously
found (suspected) novae in M 31 GCs we used our high-cadence X-ray monitoring
observations to estimate a tentative nova rate in the M 31 GC system of 0.05
/yr/GC. An optical estimate, based on the recent 10.5-year WeCAPP survey, gives
a lower nova rate, which is compatible with the X-ray rate on the 95%
confidence level. There is growing evidence that the nova rate in GCs is higher
than expected from primordial binary formation and under conditions as in the
field. Dynamical binary formation and/or additional accretion from the
intracluster medium are possible scenarios for an increased nova rate, but
observational confirmation for this enhancement has been absent, so far.
Regular X-ray monitoring observations of M 31 provide a promising strategy to
find these novae.

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The categories of this paper are: physics
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
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The categories of this paper are: adap-org
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph