The electromagnetic counterpart of the binary neutron star merger LIGO/Virgo GW170817. I. Discovery of the optical counterpart using the Dark Energy Camera

Soares-Santos, M. and Holz, D.E. and Annis, J. and Chornock, R. and Herner, K. and Berger, E. and Brout, D. and Chen, H.-Y. and Kessler, R. and Sako, M. and Allam, S. and Tucker, DL. and Butler, R. E. and Palmese, A. and Doctor, Z. and Diehl, H.T. and Frieman, J. and Yanny, B. and Lin, H. and Scolnic, D. and Cowperthwaite, P. and Neilsen, E. and Marriner, J. and Kuropatkin, N. and Hartley, W.G. and Paz-Chinchón, F. and Alexander, K.D. and Balbinot, E. and Blanchard, P. and Brown, D.A. and Carlin, J.L. and Conselice, Christopher J. and Cook, E.R. and Drlica-Wagner, A. and Drout, M.R. and Durret, F. and Eftekhari, T. and Farr, B. and Finley, D.A. and Foley, R.J. and Fong, W. and Fryer, C.L. and García-Bellido, J. and Gill, M.S.S. and Gruendl, R.A. and Hanna, C. and Kasen, D. and Li, T.S. and Lopes, P.A.A. and Lourenço, A.C.C. and Margutti, R. and Marshall, J.L. and Matheson, T. and Medina, G.E. and Metzger, B.D. and Muñoz, R.R. and Muir, J. and Nicholl, M. and Quataert, E. and Rest, A. and Sauseda, M. and Schlegel, D.J. and Secco, L.F. and Sobreira, F. and Stebbins, A. and Villar, V.A. and Vivas, K. and Walker, A.R. and Wester, W. and Williams, P.K.G. and Zenteno, A. and Zhang, Y. and Abbott, T.M.C. and Abdalla, F.B. and Banerji, M. and Bechtol, K. and Benoit-Lévy, A. and Bertin, E. and Brooks, D. and Buckley-Geer, E. and Burke, D.L. and Rosell, A. Carnero and Kind, M. Carrasco and Carretero, J. and Castander, F.J. and Crocce, M. and Cunha, C.E. and D’Andrea, C.B. and Costa, L.N. da and Davis, C. and Desai, S. and Dietrich, J.P. and Doel, P. and Eifler, T.F. and Fernandez, E. and Flaugher, B. and Fosalba, P. and Gaztanaga, E. and Gerdes, D.W. and Giannantonio, T. and Goldstein, D.A. and Gruen, D. and Gschwend, J. and Gutierrez, G. and Honscheid, K. and Jain, B. and James, D.J. and Jeltema, T. and Johnson, M.W.G. and Johnson, M.D. and Kent, S. and Krause, E. and Kron, R. and Kuehn, K. and Kuhlmann, S. and Lahav, O. and Lima, M. and Maia, M.A.G. and March, M. and McMahon, R.G. and Menanteau, F. and Miquel, R. and Mohr, J.J. and Nichol, R.C. and Nord, B. and Ogando, R.L C. and Petravick, D. and Plazas, A.A. and Romer, A.K. and Roodman, A. and Rykoff, E.S. and Sanchez, E. and Scarpine, V. and Schubnell, M. and Sevilla-Noarbe, I. and Smith, M. and Smith, R.C. and Suchyta, E. and Swanson, M.E.C. and Tarle, G. and Thomas, D. and Thomas, R.C. and Troxel, M.A. and Vikram, V. and Wechsler, R.H. and Weller, J. (2017) The electromagnetic counterpart of the binary neutron star merger LIGO/Virgo GW170817. I. Discovery of the optical counterpart using the Dark Energy Camera. Astrophysical Journal Letters, 848 (2). pp. 1-7. ISSN 2041-8213

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Abstract

We present the Dark Energy Camera (DECam) discovery of the optical counterpart of the first binary neutron star merger detected through gravitational wave emission, GW170817. Our observations commenced 10.5 hours post-merger, as soon as the localization region became accessible from Chile. We imaged 70 deg2 in the i and z bands, covering 93% of the initial integrated localization probability, to a depth necessary to identify likely optical counterparts (e.g., a kilonova). At 11.4 hours post-merger we detected a bright optical transient located 10:600 from the nucleus of NGC4993 at redshift z = 0:0098, consistent (for H0 = 70 km s-1 Mpc-1) with the distance of 40±8 Mpc reported by the LIGO Scientific Collaboration and the Virgo Collaboration (LVC). At detection the transient had magnitudes i=17.3 and z=17.4, and thus an absolute magnitude of Mi = -15.7, in the luminosity range expected for a kilonova. We identified 1,500 potential transient candidates. Applying simple selection criteria aimed at rejecting background events such as supernovae, we find the transient associated with NGC4993 as the only remaining plausible counterpart, and reject chance coincidence at the 99.5% confidence level. We therefore conclude that the optical counterpart we have identified near NGC4993 is associated with GW170817. This discovery ushers in the era of multi-messenger astronomy with gravitational waves, and demonstrates the power of DECam to identify the optical counterparts of gravitational-wave sources.

Item Type: Article
Keywords: binaries: close— catalogs— gravitational waves — stars: neutron— surveys
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.3847/2041-8213/aa9059
Depositing User: Eprints, Support
Date Deposited: 06 Nov 2017 13:35
Last Modified: 06 Nov 2017 19:58
URI: http://eprints.nottingham.ac.uk/id/eprint/47904

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