author = "Hosseinzadeh, G. and Cowperthwaite, P. S. and Gomez, S. and 
                         Villar, V. A. and Nicholl, M. and Margutti, R. and Berger, E. and 
                         Chornock, R. and Paterson, K. and Fong, W. and Savchenko, V. and 
                         Short, P. and Alexander, K. D. and Blanchard, P. K. and Braga, 
                         Jo{\~a}o and Calkins, M. L. and Cartier, R. and Coppejans, D. L. 
                         and Eftekhari, T. and Laskar, T. and Ly, C. and Patton, L. and 
                         Pelisoli, I. and Reichart, D. E. and Terreran, G. and Williams, P. 
                         K. G.",
          affiliation = "{Harvard \& Smithsonian} and {Observatories of the Carnegie 
                         Institute for Science} and {Harvard \& Smithsonian} and {Harvard 
                         \& Smithsonian} and {University of Edinburgh} and {Northwestern 
                         University} and {Harvard \& Smithsonian} and {Ohio University} 
                         and {Northwestern University} and {Northwestern University} and 
                         {University of Geneva} and {University of Edinburgh} and 
                         {Northwestern University} and {Harvard \& Smithsonian} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {Harvard 
                         \& Smithsonian} and {National Optical Astronomy Observatory} and 
                         {Northwestern University} and {Harvard \& Smithsonian} and 
                         {University of Bath} and {University of Arizona} and {Harvard \& 
                         Smithsonian} and {Universit{\"a}t Potsdam} and {University of 
                         North Carolina} and {Northwestern University} and {Harvard \& 
                title = "Follow-up of the neutron star bearing gravitational-wave candidate 
                         events S190425z and S190426c with MMT and SOAR",
              journal = "Astrophysical Journal Letters",
                 year = "2019",
               volume = "880",
               number = "1",
                pages = "L4",
                month = "July",
             keywords = "binaries: close, gravitational waves, methods: observational, 
                         stars: black holes, stars: neutron.",
             abstract = "On 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.",
                  doi = "10.3847/2041-8213/ab271c",
                  url = "http://dx.doi.org/10.3847/2041-8213/ab271c",
                 issn = "2041-8205 and 2041-8213",
             language = "en",
           targetfile = "hosseinzadeh_follow.pdf",
        urlaccessdate = "14 abr. 2021"