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The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. II. UV, Optical, and Near-infrared Light Curves and Comparison to Kilonova Models

  • Author(s): Cowperthwaite, PS
  • Berger, E
  • Villar, VA
  • Metzger, BD
  • Nicholl, M
  • Chornock, R
  • Blanchard, PK
  • Fong, W
  • Margutti, R
  • Soares-Santos, M
  • Alexander, KD
  • Allam, S
  • Annis, J
  • Brout, D
  • Brown, DA
  • Butler, RE
  • Chen, H-Y
  • Diehl, HT
  • Doctor, Z
  • Drout, MR
  • Eftekhari, T
  • Farr, B
  • Finley, DA
  • Foley, RJ
  • Frieman, JA
  • Fryer, CL
  • García-Bellido, J
  • Gill, MSS
  • Guillochon, J
  • Herner, K
  • Holz, DE
  • Kasen, D
  • Kessler, R
  • Marriner, J
  • Matheson, T
  • Neilsen, EH
  • Quataert, E
  • Palmese, A
  • Rest, A
  • Sako, M
  • Scolnic, DM
  • Smith, N
  • Tucker, DL
  • Williams, PKG
  • Balbinot, E
  • Carlin, JL
  • Cook, ER
  • Durret, F
  • Li, TS
  • Lopes, PAA
  • Lourenço, ACC
  • Marshall, JL
  • Medina, GE
  • Muir, J
  • Muñoz, RR
  • Sauseda, M
  • Schlegel, DJ
  • Secco, LF
  • Vivas, AK
  • Wester, W
  • Zenteno, A
  • Zhang, Y
  • Abbott, TMC
  • Banerji, M
  • Bechtol, K
  • Benoit-Lévy, A
  • Bertin, E
  • Buckley-Geer, E
  • Burke, DL
  • Capozzi, D
  • Carnero Rosell, A
  • Carrasco Kind, M
  • Castander, FJ
  • Crocce, M
  • Cunha, CE
  • D’Andrea, CB
  • Costa, LN da
  • Davis, C
  • DePoy, DL
  • Desai, S
  • Dietrich, JP
  • Drlica-Wagner, A
  • Eifler, TF
  • Evrard, AE
  • Fernandez, E
  • Flaugher, B
  • Fosalba, P
  • Gaztanaga, E
  • Gerdes, DW
  • Giannantonio, T
  • Goldstein, DA
  • Gruen, D
  • Gruendl, RA
  • Gutierrez, G
  • Honscheid, K
  • Jain, B
  • James, DJ
  • Jeltema, T
  • Johnson, MWG
  • Johnson, MD
  • Kent, S
  • Krause, E
  • Kron, R
  • Kuehn, K
  • Nuropatkin, N
  • Lahav, O
  • Lima, M
  • Lin, H
  • Maia, MAG
  • March, M
  • Martini, P
  • McMahon, RG
  • Menanteau, F
  • Miller, CJ
  • Miquel, R
  • Mohr, JJ
  • Neilsen, E
  • Nichol, RC
  • Ogando, RLC
  • Plazas, AA
  • Roe, N
  • Romer, AK
  • Roodman, A
  • Rykoff, ES
  • Sanchez, E
  • Scarpine, V
  • Schindler, R
  • Schubnell, M
  • Sevilla-Noarbe, I
  • Smith, M
  • Smith, RC
  • Sobreira, F
  • Suchyta, E
  • Swanson, MEC
  • Tarle, G
  • Thomas, D
  • Thomas, RC
  • Troxel, MA
  • Vikram, V
  • Walker, AR
  • Wechsler, RH
  • Weller, J
  • Yanny, B
  • Zuntz, J
  • et al.
Abstract

© 2017. The American Astronomical Society. All rights reserved.. We present UV, optical, and near-infrared (NIR) photometry of the first electromagnetic counterpart to a gravitational wave source from Advanced Laser Interferometer Gravitational-wave Observatory (LIGO)/Virgo, the binary neutron star merger GW170817. Our data set extends from the discovery of the optical counterpart at 0.47-18.5 days post-merger, and includes observations with the Dark Energy Camera (DECam), Gemini-South/FLAMINGOS-2 (GS/F2), and the Hubble Space Telescope (HST). The spectral energy distribution (SED) inferred from this photometry at 0.6 days is well described by a blackbody model with T ≈ 8300 K, a radius of R ≈ 4.5 × 1014cm (corresponding to an expansion velocity of v ≈ 0.3c), and a bolometric luminosity of Lbol ≈ 5 × 1041 erg s-1. At 1.5 days we find a multi-component SED across the optical and NIR, and subsequently we observe rapid fading in the UV and blue optical bands and significant reddening of the optical/NIR colors. Modeling the entire data set, we find that models with heating from radioactive decay of 56Ni, or those with only a single component of opacity from r-process elements, fail to capture the rapid optical decline and red optical/NIR colors. Instead, models with two components consistent with lanthanide-poor and lanthanide-rich ejecta provide a good fit to the data; the resulting "blue" component has Mblueej 0.1 M⊙ and vblueej ≈ 0.3c, and the "red" component has and Mredej ≈ 0.04 M⊙ and vredej ≈ 0.1 c. These ejecta masses are broadly consistent with the estimated r-process production rate required to explain the Milky Way r-process abundances, providing the first evidence that binary neutron star (BNS) mergers can be a dominant site of r-process enrichment.

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