| Abstract: | The collapse of the core of a star is expected to produce gravitational
radiation. While this process will usually produce a luminous supernova, the
optical signatue could be subluminous and a direct collapse to a black hole,
with the star just disappearing, is possible. The gravitational wave event
GW150914 reported by the LIGO Virgo Collaboration (LVC) on 2015 September 16,
was detected by a burst analysis and whose high probability spatial
localization included the Large Magellanic Cloud. Shortly after the
announcement of the event, we used the Dark Energy Camera to observe 102
deg$^2$ of the localization area, including a 38 deg$^2$ area centered on the
LMC. Using a catalog of 152 LMC luminous red supergiants, candidates to undergo
a core collapse without a visible supernova, we find that the positions of 144
of these are inside our images, and that all are detected - none have
disappeared. There are other classes of candidates: we searched existing
catalogs of red supergiants, yellow supergiants, Wolf-Rayet stars, and luminous
blue variable stars, recovering all that were inside the imaging area. Based on
our observations, we conclude that it is unlikely that GW150914 was caused by
the core collapse of a supergiant in the LMC, consistent with the LIGO
Collaboration analyses of the gravitational wave form as best described by a
binary black hole merger. We discuss how to generalize this search for future
very nearby core collapse candidates. |
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