Follow-up of the Neutron Star Bearing Gravitational-wave Candidate Events S190425z and S190426c with MMT and SOAR
Cowperthwaite, P. S.
Villar, V. A.
Alexander, K. D.
Blanchard, P. K.
Calkins, M. L.
Coppejans, D. L.
Reichart, D. E.
Williams, P. K. G.
AffiliationUniv Arizona, Steward Observ
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PublisherIOP PUBLISHING LTD
CitationHosseinzadeh, G., Cowperthwaite, P. S., Gomez, S., Villar, V. A., Nicholl, M., Margutti, R., ... & Savchenko, V. (2019). Follow-up of the Neutron Star Bearing Gravitational-wave Candidate Events S190425z and S190426c with MMT and SOAR. The Astrophysical Journal Letters, 880(1), L4.
JournalASTROPHYSICAL JOURNAL LETTERS
RightsCopyright © 2019. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractOn 2019 April 25.346 and 26.640 UT the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo gravitational-wave (GW) observatory announced the detection of the first candidate events in Observing Run 3 that contained at least one neutron star (NS). S190425z is a likely binary neutron star (BNS) merger at d(L) = 156 +/- 41 Mpc, while S190426c is possibly the first NS-black hole (BH) merger ever detected, at d(L) = 377 +/- 100 Mpc, although with marginal statistical significance. Here we report our optical follow-up observations for both events using the MMT 6.5 m telescope, as well as our spectroscopic follow-up of candidate counterparts (which turned out to be unrelated) with the 4.1 m SOAR telescope. We compare to publicly reported searches, explore the overall areal coverage and depth, and evaluate those in relation to the optical/near-infrared (NIR) kilonova emission from the BNS merger GW170817, to theoretical kilonova models, and to short gamma-ray burst (SGRB) afterglows. We find that for a GW170817-like kilonova, the partial volume covered spans up to about 40% for S190425z and 60% for S190426c. For an on-axis jet typical of SGRBs, the search effective volume is larger, but such a configuration is expected in at most a few percent of mergers. We further find that wide-field gamma-ray and X-ray limits rule out luminous on-axis SGRBs, for a large fraction of the localization regions, although these searches are not sufficiently deep in the context of the gamma-ray emission from GW170817 or off-axis SGRB afterglows. The results indicate that some optical follow-up searches are sufficiently deep for counterpart identification to about 300 Mpc, but that localizations better than 1000 deg(2) are likely essential.
VersionFinal published version
SponsorsNSF [AST-1009863, AST-1714498]; NASA [NNX10AF62G, NNX15AE50G]; LSSTC, NSF ; Brinson Foundation; Moore Foundation; NASA through the NASA Hubble Fellowship [HST-HF2-51403.001-A]; Space Telescope Science Institute [NAS 5-26555]; Royal Astronomical Society Research Fellowship; National Science Foundation [AST-1814782]; Deutsche Forschungsgemeinschaft [GE2506/12-1]; National Aeronautics and Space Administration through Chandra award [DD8-19101A, DDT-18096A]; National Aeronautics Space Administration [NAS8-03060]; Office of the Provost; Office for Research; Northwestern University Information Technology; University of Arizona; Ministerio da Ciencia, Tecnologia, Inovacoes e Comunicacoes (MCTIC) do Brasil; Michigan State University (MSU)