The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera

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

doi:10.3847/2041-8213/aa9059

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera

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

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

426 Scopus citations

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 hr 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 hr post-merger we detected a bright optical transient located from the nucleus of NGC 4993 at redshift z = 0.0098, consistent (for 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 of and , and thus an absolute magnitude of , in the luminosity range expected for a kilonova. We identified 1500 potential transient candidates. Applying simple selection criteria aimed at rejecting background events such as supernovae, we find the transient associated with NGC 4993 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 NGC 4993 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.

Original language	English (US)
Article number	L16
Journal	Astrophysical Journal Letters
Volume	848
Issue number	2
DOIs	https://doi.org/10.3847/2041-8213/aa9059
State	Published - Oct 20 2017

Funding

We thank the University of Copenhagen, DARK Cosmology Centre, and the Niels Bohr International Academy for hosting R.J.F., Z.D., and B.F. during the discovery of GW170817/ SSS17a, where they were participating in the Kavli Summer Program in Astrophysics, “Astrophysics with gravitational wave detections.” This program was supported by the Kavli Foundation, Danish National Research Foundation, the Niels Bohr International Academy, and the DARK Cosmology Centre. H.Y.C., Z.D., B.F., M.F., and D.E.H. were partially supported by NSF CAREER grant PHY-1151836 and NSF grant PHYS-1708081. They were also supported by the Kavli Institute for Cosmological Physics at the University of Chicago through NSF grant PHY-1125897 and an endowment from the Kavli Foundation. Funding for the DES Projects has been provided by the DOE and NSF (USA), MEC/MICINN/MINECO (Spain), STFC (UK), HEFCE (UK). NCSA (UIUC), KICP (U. Chicago), CCAPP (Ohio State), MIFPA (Texas A&M), CNPQ, FAPERJ, FINEP (Brazil), DFG (Germany), and the Collaborating Institutions in the Dark Energy Survey. This Letter has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The UCSC group is supported in part by NSF grant AST– 1518052, the Gordon & Betty Moore Foundation, the Heising-Simons Foundation, generous donations from many individuals through a UCSC Giving Day grant, and from fellowships from the Alfred P. Sloan Foundation and the David and Lucile Packard Foundation to R.J.F. The Berger Time-Domain Group at Harvard is supported in part by the NSF through grants AST-1411763 and AST-1714498, and by NASA through grants NNX15AE50G and NNX16AC22G. The DES Data Management System is supported by the NSF under grant numbers AST-1138766 and AST-1536171. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, and Centro de Excelencia SEV-2012-0234, SEV-2016-0597 and MDM-2015-0509. Research leading to these results has received funding from the ERC under the EU’s 7th Framework Programme including grants ERC 240672, 291329 and 306478. We acknowledge support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020.

Keywords

binaries: close
catalogs
gravitational waves
stars: neutron
surveys

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.3847/2041-8213/aa9059

Cite this

Soares-Santos, M., Holz, D. E., Annis, J., Chornock, R., Herner, K., Berger, E., Brout, D., Chen, H. Y., Kessler, R., Sako, M., Allam, S., Tucker, D. L., Butler, R. E., Palmese, A., Doctor, Z., Diehl, H. T., Frieman, J., Yanny, B., Lin, H., ... 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), Article L16. https://doi.org/10.3847/2041-8213/aa9059

@article{059b765f63154623bb20721ea7c1990b,

title = "The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera",

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 hr 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 hr post-merger we detected a bright optical transient located from the nucleus of NGC 4993 at redshift z = 0.0098, consistent (for 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 of and , and thus an absolute magnitude of , in the luminosity range expected for a kilonova. We identified 1500 potential transient candidates. Applying simple selection criteria aimed at rejecting background events such as supernovae, we find the transient associated with NGC 4993 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 NGC 4993 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.",

keywords = "binaries: close, catalogs, gravitational waves, stars: neutron, surveys",

author = "M. Soares-Santos and Holz, {D. E.} and J. Annis and R. Chornock and K. Herner and E. Berger and D. Brout and Chen, {H. Y.} and R. Kessler and M. Sako and S. Allam and Tucker, {D. L.} and Butler, {R. E.} and A. Palmese and Z. Doctor and Diehl, {H. T.} and J. Frieman and B. Yanny and H. Lin and D. Scolnic and P. Cowperthwaite and E. Neilsen and J. Marriner and N. Kuropatkin and Hartley, {W. G.} and F. Paz-Chinch{\'o}n and Alexander, {K. D.} and E. Balbinot and P. Blanchard and Brown, {D. A.} and Carlin, {J. L.} and C. Conselice and Cook, {E. R.} and A. Drlica-Wagner and Drout, {M. R.} and F. Durret and T. Eftekhari and B. Farr and Finley, {D. A.} and Foley, {R. J.} and W. Fong and Fryer, {C. L.} and J. Garc{\'i}a-Bellido and Gill, {M. S.S.} and Gruendl, {R. A.} and C. Hanna and D. Kasen and Li, {T. S.} and Lopes, {P. A.A.} and Louren{\c c}o, {A. C.C.} and R. Margutti and Marshall, {J. L.} and T. Matheson and Medina, {G. E.} and Metzger, {B. D.} and Mu{\~n}oz, {R. R.} and J. Muir and M. Nicholl and E. Quataert and A. Rest and M. Sauseda and Schlegel, {D. J.} and Secco, {L. F.} and F. Sobreira and A. Stebbins and Villar, {V. A.} and Walker, {A. R.} and W. Wester and Williams, {P. K.G.} and A. Zenteno and Y. Zhang and Abbott, {T. M.C.} and Abdalla, {F. B.} and M. Banerji and K. Bechtol and A. Benoit-L{\'e}vy and E. Bertin and D. Brooks and E. Buckley-Geer and Burke, {D. L.} and Rosell, {A. Carnero} and Kind, {M. Carrasco} and J. Carretero and Castander, {F. J.} and M. Crocce and Cunha, {C. E.} and D'Andrea, {C. B.} and Costa, {L. N.Da} and C. Davis and S. Desai and Dietrich, {J. P.} and P. Doel and Eifler, {T. F.} and E. Fernandez and B. Flaugher and P. Fosalba and E. Gaztanaga and Gerdes, {D. W.} and T. Giannantonio and Goldstein, {D. A.} and D. Gruen and J. Gschwend and G. Gutierrez and K. Honscheid and B. Jain and James, {D. J.} and T. Jeltema and Johnson, {M. W.G.} and Johnson, {M. D.} and S. Kent and E. Krause and R. Kron and K. Kuehn and S. Kuhlmann and O. Lahav and M. Lima and Maia, {M. A.G.} and M. March and McMahon, {R. G.} and F. Menanteau and R. Miquel and Mohr, {J. J.} and Nichol, {R. C.} and B. Nord and Ogando, {R. L.C.} and D. Petravick and Plazas, {A. A.} and Romer, {A. K.} and A. Roodman and Rykoff, {E. S.} and E. Sanchez and V. Scarpine and M. Schubnell and I. Sevilla-Noarbe and M. Smith and Smith, {R. C.} and E. Suchyta and Swanson, {M. E.C.} and G. Tarle and D. Thomas and Thomas, {R. C.} and Troxel, {M. A.} and V. Vikram and Wechsler, {R. H.} and J. Weller",

year = "2017",

month = oct,

day = "20",

doi = "10.3847/2041-8213/aa9059",

language = "English (US)",

volume = "848",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "American Astronomical Society",

number = "2",

}

Soares-Santos, M, Holz, DE, Annis, J, Chornock, R, Herner, K, Berger, E, Brout, D, Chen, HY, Kessler, R, Sako, M, Allam, S, Tucker, DL, Butler, RE, Palmese, A, Doctor, Z, Diehl, HT, Frieman, J, Yanny, B, Lin, H, Scolnic, D, Cowperthwaite, P, Neilsen, E, Marriner, J, Kuropatkin, N, Hartley, WG, Paz-Chinchón, F, Alexander, KD, Balbinot, E, Blanchard, P, Brown, DA, Carlin, JL, Conselice, C, Cook, ER, Drlica-Wagner, A, Drout, MR, Durret, F, Eftekhari, T, Farr, B, Finley, DA, Foley, RJ, Fong, W, Fryer, CL, García-Bellido, J, Gill, MSS, Gruendl, RA, Hanna, C, Kasen, D, Li, TS, Lopes, PAA, Lourenço, ACC, Margutti, R, Marshall, JL, Matheson, T, Medina, GE, Metzger, BD, Muñoz, RR, Muir, J, Nicholl, M, Quataert, E, Rest, A, Sauseda, M, Schlegel, DJ, Secco, LF, Sobreira, F, Stebbins, A, Villar, VA, Walker, AR, Wester, W, Williams, PKG, Zenteno, A, Zhang, Y, Abbott, TMC, Abdalla, FB, Banerji, M, Bechtol, K, Benoit-Lévy, A, Bertin, E, Brooks, D, Buckley-Geer, E, Burke, DL, Rosell, AC, Kind, MC, Carretero, J, Castander, FJ, Crocce, M, Cunha, CE, D'Andrea, CB, Costa, LND, Davis, C, Desai, S, Dietrich, JP, Doel, P, Eifler, TF, Fernandez, E, Flaugher, B, Fosalba, P, Gaztanaga, E, Gerdes, DW, Giannantonio, T, Goldstein, DA, Gruen, D, Gschwend, J, Gutierrez, G, Honscheid, K, Jain, B, James, DJ, Jeltema, T, Johnson, MWG, Johnson, MD, Kent, S, Krause, E, Kron, R, Kuehn, K, Kuhlmann, S, Lahav, O, Lima, M, Maia, MAG, March, M, McMahon, RG, Menanteau, F, Miquel, R, Mohr, JJ, Nichol, RC, Nord, B, Ogando, RLC, Petravick, D, Plazas, AA, Romer, AK, Roodman, A, Rykoff, ES, Sanchez, E, Scarpine, V, Schubnell, M, Sevilla-Noarbe, I, Smith, M, Smith, RC, Suchyta, E, Swanson, MEC, Tarle, G, Thomas, D, Thomas, RC, Troxel, MA, Vikram, V, Wechsler, RH & 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, vol. 848, no. 2, L16. https://doi.org/10.3847/2041-8213/aa9059

TY - JOUR

T1 - The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera

AU - Soares-Santos, M.

AU - Holz, D. E.

AU - Annis, J.

AU - Chornock, R.

AU - Herner, K.

AU - Berger, E.

AU - Brout, D.

AU - Chen, H. Y.

AU - Kessler, R.

AU - Sako, M.

AU - Allam, S.

AU - Tucker, D. L.

AU - Butler, R. E.

AU - Palmese, A.

AU - Doctor, Z.

AU - Diehl, H. T.

AU - Frieman, J.

AU - Yanny, B.

AU - Lin, H.

AU - Scolnic, D.

AU - Cowperthwaite, P.

AU - Neilsen, E.

AU - Marriner, J.

AU - Kuropatkin, N.

AU - Hartley, W. G.

AU - Paz-Chinchón, F.

AU - Alexander, K. D.

AU - Balbinot, E.

AU - Blanchard, P.

AU - Brown, D. A.

AU - Carlin, J. L.

AU - Conselice, C.

AU - Cook, E. R.

AU - Drlica-Wagner, A.

AU - Drout, M. R.

AU - Durret, F.

AU - Eftekhari, T.

AU - Farr, B.

AU - Finley, D. A.

AU - Foley, R. J.

AU - Fong, W.

AU - Fryer, C. L.

AU - García-Bellido, J.

AU - Gill, M. S.S.

AU - Gruendl, R. A.

AU - Hanna, C.

AU - Kasen, D.

AU - Li, T. S.

AU - Lopes, P. A.A.

AU - Lourenço, A. C.C.

AU - Margutti, R.

AU - Marshall, J. L.

AU - Matheson, T.

AU - Medina, G. E.

AU - Metzger, B. D.

AU - Muñoz, R. R.

AU - Muir, J.

AU - Nicholl, M.

AU - Quataert, E.

AU - Rest, A.

AU - Sauseda, M.

AU - Schlegel, D. J.

AU - Secco, L. F.

AU - Sobreira, F.

AU - Stebbins, A.

AU - Villar, V. A.

AU - Walker, A. R.

AU - Wester, W.

AU - Williams, P. K.G.

AU - Zenteno, A.

AU - Zhang, Y.

AU - Abbott, T. M.C.

AU - Abdalla, F. B.

AU - Banerji, M.

AU - Bechtol, K.

AU - Benoit-Lévy, A.

AU - Bertin, E.

AU - Brooks, D.

AU - Buckley-Geer, E.

AU - Burke, D. L.

AU - Rosell, A. Carnero

AU - Kind, M. Carrasco

AU - Carretero, J.

AU - Castander, F. J.

AU - Crocce, M.

AU - Cunha, C. E.

AU - D'Andrea, C. B.

AU - Costa, L. N.Da

AU - Davis, C.

AU - Desai, S.

AU - Dietrich, J. P.

AU - Doel, P.

AU - Eifler, T. F.

AU - Fernandez, E.

AU - Flaugher, B.

AU - Fosalba, P.

AU - Gaztanaga, E.

AU - Gerdes, D. W.

AU - Giannantonio, T.

AU - Goldstein, D. A.

AU - Gruen, D.

AU - Gschwend, J.

AU - Gutierrez, G.

AU - Honscheid, K.

AU - Jain, B.

AU - James, D. J.

AU - Jeltema, T.

AU - Johnson, M. W.G.

AU - Johnson, M. D.

AU - Kent, S.

AU - Krause, E.

AU - Kron, R.

AU - Kuehn, K.

AU - Kuhlmann, S.

AU - Lahav, O.

AU - Lima, M.

AU - Maia, M. A.G.

AU - March, M.

AU - McMahon, R. G.

AU - Menanteau, F.

AU - Miquel, R.

AU - Mohr, J. J.

AU - Nichol, R. C.

AU - Nord, B.

AU - Ogando, R. L.C.

AU - Petravick, D.

AU - Plazas, A. A.

AU - Romer, A. K.

AU - Roodman, A.

AU - Rykoff, E. S.

AU - Sanchez, E.

AU - Scarpine, V.

AU - Schubnell, M.

AU - Sevilla-Noarbe, I.

AU - Smith, M.

AU - Smith, R. C.

AU - Suchyta, E.

AU - Swanson, M. E.C.

AU - Tarle, G.

AU - Thomas, D.

AU - Thomas, R. C.

AU - Troxel, M. A.

AU - Vikram, V.

AU - Wechsler, R. H.

AU - Weller, J.

PY - 2017/10/20

Y1 - 2017/10/20

N2 - 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 hr 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 hr post-merger we detected a bright optical transient located from the nucleus of NGC 4993 at redshift z = 0.0098, consistent (for 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 of and , and thus an absolute magnitude of , in the luminosity range expected for a kilonova. We identified 1500 potential transient candidates. Applying simple selection criteria aimed at rejecting background events such as supernovae, we find the transient associated with NGC 4993 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 NGC 4993 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.

AB - 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 hr 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 hr post-merger we detected a bright optical transient located from the nucleus of NGC 4993 at redshift z = 0.0098, consistent (for 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 of and , and thus an absolute magnitude of , in the luminosity range expected for a kilonova. We identified 1500 potential transient candidates. Applying simple selection criteria aimed at rejecting background events such as supernovae, we find the transient associated with NGC 4993 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 NGC 4993 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.

KW - binaries: close

KW - catalogs

KW - gravitational waves

KW - stars: neutron

KW - surveys

UR - http://www.scopus.com/inward/record.url?scp=85031941432&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85031941432&partnerID=8YFLogxK

U2 - 10.3847/2041-8213/aa9059

DO - 10.3847/2041-8213/aa9059

M3 - Article

AN - SCOPUS:85031941432

SN - 2041-8205

VL - 848

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L16

ER -

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera

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Counterpart of GW170817. I. DECam obs.

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The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. I. Discovery of the Optical Counterpart Using the Dark Energy Camera

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Counterpart of GW170817. I. DECam obs.

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