Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Swift-XRT Follow-up of Gravitational-wave Triggers in the Second Advanced LIGO/Virgo Observing Run
AU - Klingler, N. J.
AU - Kennea, J. A.
AU - Evans, P. A.
AU - Tohuvavohu, A.
AU - Cenko, S. B.
AU - Barthelmy, S. D.
AU - Beardmore, A. P.
AU - Breeveld, A. A.
AU - Brown, P. J.
AU - Burrows, D. N.
AU - Campana, S.
AU - Cusumano, G.
AU - D'Aì, A.
AU - D'Avanzo, P.
AU - D'Elia, V.
AU - de Pasquale, M.
AU - Emery, S. W. K.
AU - Garcia, J.
AU - Giommi, P.
AU - Gronwall, C.
AU - Hartmann, D. H.
AU - Krimm, H. A.
AU - Kuin, N. P. M.
AU - Lien, A.
AU - Malesani, D. B.
AU - Marshall, F. E.
AU - Melandri, A.
AU - Nousek, J. A.
AU - Oates, S. R.
AU - O'Brien, P. T.
AU - Osborne, J. P.
AU - Page, K. L.
AU - Palmer, D. M.
AU - Perri, M.
AU - Racusin, J. L.
AU - Siegel, M. H.
AU - Sakamoto, T.
AU - Sbarufatti, B.
AU - Tagliaferri, G.
AU - Troja, E.
PY - 2019/11/15
Y1 - 2019/11/15
N2 - The Neil Gehrels Swift Observatory carried out prompt searches for gravitational-wave (GW) events detected by the LIGO/Virgo Collaboration (LVC) during the second observing run (“O2”). Swift 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 Swift 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....
AB - The Neil Gehrels Swift Observatory carried out prompt searches for gravitational-wave (GW) events detected by the LIGO/Virgo Collaboration (LVC) during the second observing run (“O2”). Swift 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 Swift 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....
U2 - 10.3847/1538-4365/ab4ea2
DO - 10.3847/1538-4365/ab4ea2
M3 - Journal article
VL - 245
JO - The Astrophysical Journal Supplement Series
JF - The Astrophysical Journal Supplement Series
SN - 0067-0049
IS - 1
M1 - 15
ER -