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

Journal Article · 16 October 2017 · The Astrophysical Journal. Letters (Online)

DOI: https://doi.org/10.3847/2041-8213/aa8fc7 · OSTI ID:1421833

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

Here, 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 $$T\approx 8300$$ K, a radius of $$R\approx 4.5\times {10}^{14}$$ cm (corresponding to an expansion velocity of $$v\approx 0.3c$$), and a bolometric luminosity of $${L}_{\mathrm{bol}}\approx 5\times {10}^{41}$$ 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 $${M}_{\mathrm{ej}}^{\mathrm{blue}}\approx 0.01\,{M}_{\odot }$$ and $${v}_{\mathrm{ej}}^{\mathrm{blue}}\approx 0.3\,{\rm{c}}$$, and the "red" component has $${M}_{\mathrm{ej}}^{\mathrm{red}}\approx 0.04\,{M}_{\odot }$$ and $${v}_{\mathrm{ej}}^{\mathrm{red}}\approx 0.1\,{\rm{c}}$$. 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.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)
• Grant/Contract Number: AC02-05CH11231; AC02-76SF00515; AC02-07CH11359; AC05-00OR22725
• OSTI ID: 1421833
• Alternate ID(s): OSTI ID: 1407127; OSTI ID: 1409348; OSTI ID: 1422480
• Report Number(s): arXiv:1710.05840; FERMILAB-PUB-17-470-A-AE-CD-PPD; ark:/13030/qt0wc6v6pt; TRN: US1801566
• Journal Information: The Astrophysical Journal. Letters (Online), Vol. 848, Issue 2; ISSN 2041-8213
• Publisher: Institute of Physics (IOP)Copyright Statement
• Country of Publication: United States
• Language: English