Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SN 2008iy: An Unusual Type IIn Supernova with an Enduring 400 Day Rise
  Time   We present spectroscopic and photometric observations of the Type IIn
supernova (SN) 2008iy. SN 2008iy showed an unprecedentedly long rise time of
~400 days, making it the first SN to take significantly longer than 100 days to
reach peak optical luminosity. The peak absolute magnitude of SN 2008iy was M_r
~ -19.1 mag, and the total radiated energy over the first ~700 days was ~2 x
10^50 erg. Spectroscopically, SN 2008iy is very similar to the Type IIn SN
1988Z at late times, and, like SN 1988Z, it is a luminous X-ray source (both
supernovae had an X-ray luminosity L_ X > 10^41 erg/s). The Halpha emission
profile of SN 2008iy shows a narrow P Cygni absorption component, implying a
pre-SN wind speed of ~100 km/s. We argue that the luminosity of SN 2008iy is
powered via the interaction of the SN ejecta with a dense, clumpy circumstellar
medium. The ~400 day rise time can be understood if the number density of
clumps increases with distance over a radius ~1.7 x 10^16 cm from the
progenitor. This scenario is possible if the progenitor experienced an episodic
phase of enhanced mass-loss < 1 century prior to explosion or the progenitor
wind speed increased during the decades before core collapse. We favour the
former scenario, which is reminiscent of the eruptive mass-loss episodes
observed for luminous blue variable (LBV) stars. The progenitor wind speed and
increased mass-loss rates serve as further evidence that at least some, and
perhaps all, Type IIn supernovae experience LBV-like eruptions shortly before
core collapse. We also discuss the host galaxy of SN 2008iy, a subluminous
dwarf galaxy, and offer a few reasons why the recent suggestion that unusual,
luminous supernovae preferentially occur in dwarf galaxies may be the result of
observational biases.

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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: funct-an
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The categories of this paper are: physics
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The categories of this paper are: hep-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: gr-qc
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: bayes-an