Swift-XRT Follow-up of Gravitational-wave Triggers in the Second Advanced LIGO/Virgo Observing Run

N. J. Klingler, J. A. Kennea, P. A. Evans, A. Tohuvavohu, S. B. Cenko, S. D. Barthelmy, A. P. Beardmore, A. A. Breeveld, P. J. Brown, D. N. Burrows, S. Campana, G. Cusumano, A. D’Aì, P. D’Avanzo, V. D’Elia, M. de Pasquale, S. W. K. Emery, J. Garcia, P. Giommi, C. Gronwall, D. H. Hartmann, H. A. Krimm, N. P. M. Kuin, A. Lien, D. B. Malesani, F. E. Marshall, A. Melandri, J. A. Nousek, S. R. Oates, P. T. O’Brien, J. P. Osborne, K. L. Page, D. M. Palmer, M. Perri, J. L. Racusin, M. H. Siegel, T. Sakamoto, B. Sbarufatti, G. Tagliaferri, E. Troja

doi:10.48550/arxiv.1909.11586

<jats:title>Abstract</jats:title> <jats:p>The <jats:italic>Neil Gehrels Swift Observatory</jats:italic> carried out prompt searches for gravitational-wave (GW) events detected by the LIGO/Virgo Collaboration (LVC) during the second observing run (“O2”). <jats:italic>Swift</jats:italic> performed extensive tiling of eight LVC triggers, two of which had very low false-alarm rates (GW170814 and the epochal GW170817), indicating a high confidence of being astrophysical in origin; the latter was the first GW event to have an electromagnetic counterpart detected. In this paper we describe the follow-up performed during O2 and the results of our searches. No GW electromagnetic counterparts were detected; this result is expected, as GW170817 remained the only astrophysical event containing at least one neutron star after LVC’s later retraction of some events. A number of X-ray sources were detected, with the majority of identified sources being active galactic nuclei. We discuss the detection rate of transient X-ray sources and their implications in the O2 tiling searches. Finally, we describe the lessons learned during O2 and how these are being used to improve the <jats:italic>Swift</jats:italic> follow-up of GW events. In particular, we simulate a population of gamma-ray burst afterglows to evaluate our source ranking system’s ability to differentiate them from unrelated and uncataloged X-ray sources. We find that ≈60%–70% of afterglows whose jets are oriented toward Earth will be given high rank (i.e., “interesting” designation) by the completion of our second follow-up phase (assuming that their location in the sky was observed), but that this fraction can be increased to nearly 100% by performing a third follow-up observation of sources exhibiting fading behavior.</jats:p>

Swift-XRT Follow-up of Gravitational-wave Triggers in the Second Advanced LIGO/Virgo Observing Run

Search this article

Description

Journal

Citations (3)*help

References(57)*help

Related Data

Related Projects

Keywords

Details 詳細情報について

Export

Report a problem