Galaxy-Targeting Approach Optimized for Finding the Radio Afterglows of Gravitational Wave Sources. (arXiv:1904.07335v1 [astro-ph.IM])

Galaxy-Targeting Approach Optimized for Finding the Radio Afterglows of Gravitational Wave Sources. (arXiv:1904.07335v1 [astro-ph.IM])
<a href="http://arxiv.org/find/astro-ph/1/au:+Rana_J/0/1/0/all/0/1">Javed Rana</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mooley_K/0/1/0/all/0/1">Kunal P. Mooley</a>

Kilonovae and radio afterglows of neutron star merger events have been
identified as the two most promising counterparts, of these gravitational wave
sources, that can provide arcsecond localization. While several new and
existing optical search facilities have been dedicated to finding kilonovae,
factors such as dust obscuration and the daytime sky may thwart these searches
in a significant fraction of gavitational wave events. Radio-only searches,
being almost immune to these factors, are equally capable of finding the
counterparts and in fact offer a complementary discovery approach, despite the
modest fields of view for many of the present-day radio interferometers. Such
interferometers will be able to carry out competitive searches for the
electromagnetic counterparts through the galaxy targeting approach. Adapting
and improving on an existing algorithm by Rana et al. 2017. we present here a
method that optimizes the placement of radio antenna pointings, integration
time, and antenna slew. We simulate 3D gravitational wave localizations to find
the efficacy of our algorithm; with substantial improvements in slew overhead
and containment probability coverage, our algorithm performs significantly
better than simple galaxy-rank-ordered observations. We propose that telescopes
such as the Very Large Array, MeerKAT, Australia Telescope Compact Array and
the Gaint Meterwave Radio Telescope, having fields of view $lesssim$1 deg$^2$
and searching for the counterparts of nearby GW events over tens of square
degrees or larger, will especially benefit from this optimized galaxy-targeting
approach for electromagnetic counterpart searches.

Kilonovae and radio afterglows of neutron star merger events have been
identified as the two most promising counterparts, of these gravitational wave
sources, that can provide arcsecond localization. While several new and
existing optical search facilities have been dedicated to finding kilonovae,
factors such as dust obscuration and the daytime sky may thwart these searches
in a significant fraction of gavitational wave events. Radio-only searches,
being almost immune to these factors, are equally capable of finding the
counterparts and in fact offer a complementary discovery approach, despite the
modest fields of view for many of the present-day radio interferometers. Such
interferometers will be able to carry out competitive searches for the
electromagnetic counterparts through the galaxy targeting approach. Adapting
and improving on an existing algorithm by Rana et al. 2017. we present here a
method that optimizes the placement of radio antenna pointings, integration
time, and antenna slew. We simulate 3D gravitational wave localizations to find
the efficacy of our algorithm; with substantial improvements in slew overhead
and containment probability coverage, our algorithm performs significantly
better than simple galaxy-rank-ordered observations. We propose that telescopes
such as the Very Large Array, MeerKAT, Australia Telescope Compact Array and
the Gaint Meterwave Radio Telescope, having fields of view $lesssim$1 deg$^2$
and searching for the counterparts of nearby GW events over tens of square
degrees or larger, will especially benefit from this optimized galaxy-targeting
approach for electromagnetic counterpart searches.

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